| PATENT ASSIGNEE'S COUNTRY | Canada |
| UPDATE | 01.00 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 18.01.00 |
| PATENT TITLE |
Transferrin receptor genes |
| PATENT ABSTRACT |
Purified and isolated nucleic acid is provided which encodes a transferrin receptor protein of a strain of Haemophilus or a fragment or an analog of the transferrin receptor protein. The nucleic acid sequence may be used to produce peptides free of contaminants derived from bacteria normally containing the Tbp1 or Tbp2 proteins for purposes of diagnostics and medical treatment. Furthermore, the nucleic acid molecule may be used in the diagnosis of infection. Also provided are recombinant Tbp1 or Tbp2 and methods for purification of the same. Live vectors expressing epitopes of transferrin receptor protein for vaccination are provided. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 07.06.95 |
| PATENT REFERENCES CITED |
Orkin et al., Report and recommendations of the panel to asses the NIH investment in research on gene therapy, Dec. 7, 1995. Holland et al., Evidence for in vivo expression of transferrin binding proteins in Haemophilus influenzae type b, Infection and Immunity, v. 60(7), pp. 2986-2991, Jul. 1992. Legrain et al., Cloning and characterization of the Neisseria meningitidis genes encoding the transferrin binding proteins Tbp 1 and Tbp2*, Gene, v. 130, pp. 73-80, Aug. 1993. Loosmore et al., Cloning and expression of the Haemophilus influenzae transferrin receptor genes, Molecular Microbiology, v. 19(3), pp. 575-586, 1996. Sambrook et al., Molecular Cloning: a laboratory manual, Cold Spring Harbor Press, chapters 16-17, 1989. Vonder Haar et al., Characterization of a highly structured domain in Tbp2 from Neisseria meningitidis involved in binding to human transferrin, Journal of Bacteriology, v. 176(20), pp. 6207-6213, Oct. 1994. Barcak et al, (1991) Methods Enzymol. 204: 321-342. Berkowitz et al, (1987) J. Pediatr. 110:509. Black et al, (1991) Pediatr. Infect. Dis. J. 10:97. Bluestone, N. (1982) Engl. J. Med. 306;1399. Chang et al, (1978) Nature 375:615. Claesson et al, (1989) J. Pediatr. 114:97. Cornelissen et al, (1992) J. Bacteriol. 174:5788. Danve, et al, (1993) Vaccine 11, 1214-1220. Deres et al, (1989) Nature 342;651. Gerlach et al, (1992) Infect. Immun. 608:325. Goeddel et al, (1979) Nature 281:544. Chou et al, (1978) Annual Reviews of Biochemistry 47, 251-276. Harkness et al, (1992) J. Bacteriol. 174:2425. Holland et al, (1992) Infect. Immun. 60:2986. Hopp. T.P., (1986) Journal of Immunological Methods 88:1-18. Itakura et al, (1977) Science 198:1056. Jarosik et al, (1994) Infection and Immunity 62: 2470-2477. Legrain et al, (1993) Gene 130:73. Lockhoff et al, (1991) Chem. Int. Ed. Engl. 30:1611. Mickelsen and Sparling, (1981) Infect. Immun. 33:555. Morton et al, (1993) Infection and Immunity 61: 4033-4037. Murdin et al, (1992) J. Gen. Viral 73:607. Murdin et al, (1991) Microbial Pathogenesis 10:27. Nixon-George et al (1990) J. Immunol. 14:4798. Ogunnariwo et al, (1992) Avian Dis. 36:655. O'Hagan (1992) Clin. Pharmokinet. 22:1. Panezutti et al, (1993) Infection and Immunity, 61:1867-1872. Roosi-Campos et al, (1992) Vaccine 10,:512-518. Schryvers, (1988) Molec. Microbiol. 2:467. Schryvers and Lee, (1989) Can. J. Microbiol. 35:409. Schryvers and Gray-Owen, (1992) J. Infect. Dis. 165 suppl 1:S103. Schryvers (1989) Med. Microbiol. 29:121. Short et al, (1988) Nucl. Acids Res. 16:7583. Ulmer et al (1993) Curr. Opinion Invest. Drugs. 2(9):983-989. VanderWerf et al, (1986) Proc. Natl. Acad. Sci. 83:2330. Weismuller et al, (1989) Vaccine 8:29. Wilton et al, (1993) FEMS Microbiology Letters 107:59-66. Sambrook et al, Molecular Cloning, A Lab Manual. vol. 3, pp. 16.2, 16.3 and pp. 17.2-17.28. Ghrayeb et al, Embo J. vol. 3, pp. 2437-2442, (1984). Thomas et al, methods in Enzymology, vol. 182, pp.499-520, (1990). Gray-Owen et al, Infect. Immun., vol 63; No. 4 (1995) pp. 1201-1210. Griffiths et al, Fems Microbiol. Lett. vol. 109, No. 1 -May 1993. pp. 85-91 . |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What we claim is: 1. An isolated and purified nucleic acid molecule which encodes an immunogenic truncated analog of a transferrin receptor protein selected from the group consisting of Tbp1 and Tbp2 proteins of a strain of Haemophilus and which is truncated from the C-terminus of the transferrin receptor protein. 2. An isolated and purified nucleic acid molecule which encodes only a C-terminally truncated Tbp2 protein of a Haemophilus strain. 3. An expression vector adapted for transformation of a host comprising a nucleic acid molecule encoding a C-terminally, truncated Tbp2 protein of a Haemophilus strain and expression means operatively coupled to the nucleic acid molecule for expression by the host of a C-terminally truncated Tbp2 protein of a strain of Haemophilus. 4. The expression vector of claim 3 which is selected from the group consisting of the clones DS-1466-1-1, DS-1466-1-14 and DS-1466-2-6 of Table 8. 5. A method of making a truncated Tbp2 protein of a Haemophilus strain, which comprises: constructing an expression vector comprising a nucleic acid molecule encoding a C-terminally truncated Tbp2 protein of a Haemophilus strain operatively connected to a control sequence for expression of the C-terminally truncated Tbp2 protein in a host; introducing said expression vector into said host; and expressing the C-terminally truncated Tbp2 protein from the host. 6. The method of claim 5 which said expression vector is selected from the group consisting of the expression vectors DS-1466-1-1, DS-1466-1-14 and DS-1466-2-6 of Table 8. 7. The nucleic acid molecule of claim 2 which encodes a truncated Tbp2 protein shown in FIG. 31 for Eagan strain and selected from the group consisting of SEQ ID no: 149, SEQ ID no: 150 and SEQ ID no: 151 or which encodes a corresponding C-terminally truncated Tbp2 protein of another Haemophilus strain. |
| PATENT DESCRIPTION |
FIELD OF INVENTION The present invention is related to the molecular cloning of genes encoding transferrin receptor and in particular to the cloning of transferrin receptor genes from Haemophilus influenzae. BACKGROUND OF THE INVENTION Encapsulated Haemophilus influenzae type b strains are the major cause of bacterial meningitis and other invasive infections in young children. However, the non-encapsulated or non-typable H. influenzae (NTHi) are responsible for a wide range of human diseases including otitis media, epiglottitis, pneumonia, and tracheobronchitis. Vaccines based upon H. influenzae type b capsular polysaccharide conjugated to diptheria toxoid (Berkowitz et al., 1987. Throughout this application, various references are referred to in parenthesis to more fully describe the state of the art to which this invention pertains. Full bibliographic information for each citation is found at the end of the specification, immediately preceding the claims. The disclosures of these references are hereby incorporated by reference into the present disclosure), tetanus toxoid (Classon et al., 1989 and U.S. Pat. No. 4,496,538), or Neisseria meningitidis outer membrane protein (Black et al., 1991) have been effective in reducing H. influenzae type b-induced meningitis, but not NTHi-induced disease (Bluestone, 1982). Otitis media is the most common illness of early childhood with 60-70% of all children of less than 2 years of age experiencing between one and three ear infections. Chronic otitis media is responsible for hearing, speech and cognitive impairments in children. H. influenzae infections account for about 30% of the cases of acute otitis media and about 60% of chronic otitis media. In the United States alone, treatment of otitis media costs between 1 and 2 billion dollars per year for antibiotics and surgical procedures such as tonsillectomies, adenoidectomies and insertion of tympanostomy tubes. Furthermore, many of the causative organisms of otitis media are becoming resistant to antibiotic treatment. An effective prophylactic vaccine against otitis media is thus desirable. Non-typable strains of H. influenzae are also important pathogens responsible for pneumonia in the elderly and other individuals who are particularly susceptible to respiratory infections. There is thus a need for antigens from H. influenzae which are useful as components in immunogenic preparations that provide protection against the many serotypes of H. influenzae. Iron is an essential nutrient for the growth of many bacteria. Several human pathogens, such as H. influenzae, Branhamella catarrhalis, N. meningitidis, N. gonorrhoeae and non-pathogenic commensal Neisseria strains, can utilize human transferrin as an iron source (Schryvers, 1988; Schryvers and Lee, 1989; Mickelsen and Sparling, 1981). The bacterial transferrin receptor (TfR) is composed of two chains, Tbp1 and Tbp2. In strains of H. influenzae, the molecular weight of Tbp1 is approximately 100,000, whereas the molecular weight of Tbp2 is variable, ranging from 60,000 to 90,000, depending upon the strain (Schryvers and Gray-Owen, 1992; Holland et al., 1992). Expression of H. influenzae transferrin receptor is thought to be iron- and/or hemin-regulated (Morton et al., 1993) and a putative fur-binding site (Braun and Hantke, 1991) has been identified upstream of tbp2. This sequence is found in the promoter region of genes which are negatively regulated by iron, including N. meningitidis TfR (Legrain et al., 1993). The promoter is followed by the tbp2 and tbp1 genes, an arrangement found in other bacterial TfR operons (Legrain et al, 1993; Wilton et al., 1993). Antibodies which block the access of the transferrin receptor to its iron source may prevent bacterial growth. In addition, antibodies against TfR that are opsonizing or bactericidal may also provide protection by alternative mechanisms. Thus, the transferrin receptor, fragments thereof, its constituent chains, or peptides derived therefrom are vaccine candidates to protect against H. influenzae disease. Mice immunized with N. meningitidis TfR proteins in Freund's adjuvant were protected from homologous challenge and the anti-TfR antisera were bactericidal and protective in a passive transfer assay (Danve et al., 1993). Pigs immunized with recombinant A. pleuropneumoniae Tbp2 were protected against homologous challenge but not heterologous challenge (Rossi-Campos et al., 1992). These data indicate the efficacy of TfR-based vaccines in protection from disease. It would be desirable to provide the sequence of the DNA molecule that encodes transferrin receptor and peptides corresponding to portions of the transferrin receptor and vectors containing such sequences for diagnosis, immunization and the generation of diagnostic and immunological reagents. Poliovirus is an enterovirus, a genus of the family Picornaviridae. There are three distinct serotypes of the virus, and multiple strains within each serotype. Virulent strains are causative agents of paralytic poliomyelitis. Attenuated strains, which have reduced potential to cause paralytic disease, and inactivated virulent strains, are used as vaccines. Infection with the virus induces long-lasting, protective, mucosal immunity. Inoculation with inactivated poliovirus vaccines can also induce a mucosal immune response. The structure of poliovirus is known, and is highly conserved among strains and serotypes. The structures of several other picornaviruses (viruses belonging to genera of the family Picornaviridae) have also been determined, and have been shown to be closely related to the structure of poliovirus. It is possible to express foreign epitopes on the capsid of polioviruses (Murdin et al, 1992) and this work has been extended to other picornaviruses. Epitopes which have been expressed are usually short, well defined, contiguous epitopes, and most have been expressed within poliovirus neutralisation antigenic site I (NAgI) or the equivalent site on other picornaviruses. This site includes the loop linking beta strands B and C (the BC loop) of poliovirus capsid protein VP1. The BC loop of VP1 is a surface-exposed loop of nine amino acids which can be replaced and extended with at least twenty-five heterologous amino acids (Murdin et al, 1991). Hybrid or chimeric polioviruses expressing transferrin receptor epitopes, which grow to a high titre and are immunogenic, would be useful as vaccines and as tools for the generation of immunological reagents. SUMMARY OF THE INVENTION The present invention is directed towards the provision of purified and isolated nucleic acid molecules encoding a transferrin receptor of a strain of Haemophilus or a fragment or an analog of the transferrin receptor protein. The nucleic acid molecules provided herein are useful for the specific detection of strains of Haemophilus, and for diagnosis of infection by Haemophilus. The purified and isolated nucleic acid molecules provided herein, such as DNA, are also useful for expressing the TfR genes by recombinant DNA means for providing, in an economical manner, purified and isolated transferrin receptor subunits, fragments or analogs thereof. The transferrin receptor, subunits or fragments thereof or analogs thereof, as well as nucleic acid molecules encoding the same and vectors containing such nucleic acid molecules, are useful in immunogenic compositions against diseases caused by Haemophilus, the diagnosis of infection by Haemophilus and as tools for the generation of immunological reagents. Monoclonal antibodies or mono-specific antisera (antibodies) raised against the transferrin receptor protein produced in accordance with aspects of the present invention are useful for the diagnosis of infection by Haemophilus, the specific detection of Haemophilus (in for example in vitro and in vivo assays) and for the treatment of diseases caused by Haemophilus. Peptides corresponding to portions of the transferrin receptor or analogs thereof are useful immunogenic compositions against disease caused by Haemophilus, the diagnosis of infection by Haemophilus and as tools for the generation of immunological reagents. Monoclonal antibodies or antisera raised against these peptides, produced in accordance with aspects of the present invention, are useful for the diagnosis of infection by Haemophilus, the specific detection of Haemophilus (in, for example, in vitro and in vivo assays) and for use in passive immunization as a treatment of disease caused by Haemophilus. In accordance with one aspect of the present invention, there is provided a purified and isolated nucleic acid molecule encoding a transferrin receptor protein of a strain of Haemophilus, more particularly, a strain of H. influenzae, specifically a strain of H. influenzae type b, such as H. influenzae type b strain DL63, Eagan or MinnA, or a non-typable strain of H. influenzae, such as H. influenzae strain PAK 12085, SB33, SB12, SB29, SB30, or SB32, or a fragment or an analog of the transferrin receptor protein. In one preferred embodiment of the invention, the nucleic acid molecule may encode only the Tbp1 protein of the Haemophilus strain or only the Tbp2 protein of the Haemophilus strain. In another preferred embodiment of the invention, the nucleic acid may encode a fragment of the transferrin receptor protein of a strain of Haemophilus having a conserved amino acid sequence which is conserved among bacteria that produce transferrin receptor protein. Such conserved amino acid sequence may have an amino acid sequence contained within the amino acid sequence of the peptides shown in Tables 2 and 3 below for Haemophilus influenzae type b strain Eagan as well as corresponding peptides of other strains of Haemophilus influenzae. In another aspect of the present invention, there is provided a purified and isolated nucleic acid molecule having a DNA sequence selected from the group consisting of (a) any one of the DNA sequences set out in FIGS. 3, 4, 5, 6, 7, 8, 9, 10 or 11 (SEQ ID NOS: 1, 2, 3, 4, 105, 108, 110, 112, 114) or the complementary DNA sequence of any one of said sequences; (b) a DNA sequence encoding one of the amino acid sequences set out in FIGS. 3, 4, 5, 6, 7, 8, 9, 10, 11 or 31 (SEQ ID NOS: 5, 6, 7, 8, 9, 10, 11, 12, 106, 107, 109, 111, 113, 115) or the complementary DNA sequence thereto; and (c) a DNA sequence which hybridizes under stringent conditions to any one of the DNA sequences defined in (a) or (b). The DNA sequence defined in (c) preferably has at least about 90% sequence identity with any one of the DNA sequences defined in (a) and (b). In an additional aspect, the present invention includes a vector adapted for transformation of a host, comprising a nucleic acid molecule as provided herein. The vector may be one having the characteristics of plasmid DS-712-1-3 having ATCC accession number 75603 or plasmid JB-1042-7-6 having ATCC accession number 75607. The plasmids may be adapted for expression of the encoded transferrin receptor, fragments or analogs thereof, in a heterologous or homologous host, in either a lipidated or non-lipidated form. Accordingly, a further aspect of the present invention provides an expression vector adapted for transformation of a host comprising a nucleic acid molecule as provided herein and expression means operatively coupled to the nucleic acid molecule for expression by the host of the transferrin receptor protein or the fragment or analog of the transferrin receptor protein. In specific embodiments of this aspect of the invention, the nucleic acid molecule may encode substantially all the transferrin receptor protein, only the Tbp1 protein or only the Tbp2 protein of the Haemophilus strain. The expression means may include a nucleic acid portion encoding a leader sequence for secretion from the host of the transferrin receptor protein or the fragment or the analog of the transferrin receptor protein. The expression means also may include a nucleic acid portion encoding a lipidation signal for expression from the host of a lipidated form of the transferrin receptor protein or the fragment or the analog of the transferrin receptor protein. The expression plasmid may have the identifying characteristics of plasmid JB-1468-29, JB-1600-1 or JB-1424-2-8. The host may be selected from, for example, Escherichia coli, Bacillus, Haemophilus, fungi, yeast or baculovirus and Semliki Forest virus expression systems may be used. In an additional aspect of the invention, there is provided a transformed host containing an expression vector as provided herein. Such host may selected from JB-1476-2-1, JB-1437-4-1 and JB-1607-1-1. The invention further includes a recombinant transferrin receptor protein or fragment or analog thereof producible by the transformed host. As described in more detail below, there has been produced Tbp1 and Tbp2 protein receptors separate from each other. Further aspects of the present invention, therefore, provide an isolated and purified Tbp1 protein of a strain of Haemophilus free from the Tbp2 protein of the Haemophilus strain and an isolated and purified Tbp2 protein of a strain of Haemophilus free from the Tbp1 protein of the Haemophilus strain. The Haemophilus strain may be H. Influenzae type b or a non-typable strain of H. influenzae. The present invention further provides synthetic peptides corresponding to portions of the transferrin receptor. Accordingly, in a further aspect of the invention, there is provided a synthetic peptide having no less than six amino acids and no more than 150 amino acids and containing an amino acid sequence corresponding to a portion only of a transferrin receptor protein of a strain of bacteria or of an analog the transferrin receptor protein. The bacterial strain preferably is a Haemophilus strain, particularly a H. influenzae strain, specifically a strain of H. influenzae type b or a non-typable strain of H. influenzae. The peptides provided herein may comprise an amino acid sequence which is conserved among bacteria that produces transferrin receptor protein, including strains of Haemophilus. The peptide may include an amino acid sequence LEGGFYGP (SEQ ID NO: 74) or LEGGFYG (SEQ ID NO: 85). The peptides provided herein may have an amino acid sequence selected from those presented in Table 2 or 3 below for the Eagan strain of H. influenzae type b and corresponding amino acid sequences for other strains of H. influenzae. In accordance with another aspect of the invention, an immunogenic composition is provided which comprises at least one active component selected from at least one nucleic acid molecule as provided herein, at least one recombinant protein as provided herein, at least one of the purified and isolated Tbp1 or Tbp2 proteins, as provided herein, at least one synthetic peptide, as provided herein, at least one purified and isolated truncated Tbp2 protein, as provided herein and a live vector, as provided herein, and a pharmaceutically acceptable carrier therefor or vector therefor. The at least one active component produces an immune response when administered to a host. The immunogenic compositions provided herein may be formulated as a vaccine for in vivo administration to protect against diseases caused by bacterial pathogens that produce transferrin receptors. For such purpose, the compositions may be formulated as a microparticle, capsule or liposome preparation. Alternatively, the compositions may be provided in combination with a targeting molecule for delivery to specific cells of the immune system or to mucosal surfaces. The immunogenic composition may comprise a plurality of active components to provide protection against disease caused by a plurality of species of transferrin receptor producing bacteria. The immunogenic compositions may further comprise an adjuvant. In accordance with another aspect of the invention, there is provided a method for inducing protection against infection or disease caused by Haemophilus or other bacteria that produce transferrin receptor protein, comprising the step of administering to a susceptible host, such as a human, an effective amount of the immunogenic composition as recited above. In accordance with another aspect of the invention, an antiserum or antibody specific for the recombinant protein, the isolated and purified Tbp1 protein or Tbp2 protein, synthetic peptide or the immunogenic composition, is provided. In a further aspect, there is provided a live vector for delivery of tranferrin receptor to a host, comprising a vector containing the nucleic acid molecule as described above. The vector may be selected from Salmonella, BCG, adenovirus, poxvirus, vaccinia and poliovirus. The vector may specifically be poliovirus and the nucleic acid molecule may code for a fragment of transferrin receptor having an amino acid sequence of LEGGFYGP (SEQ ID NO: 74) or LEGGFYG (SEQ ID NO: 85). The present invention further includes a plasmid vector having the identifying characteristics of pT7TBP2A, pT7TBP2B, pT7TBP2C or pT7TBP2D (ATCC designation Nos. 75931, 75932, 75933, 75934). An additional aspect of the invention provides a strain of Haemophilus that does not produce transferrin receptor protein. Such strain may comprise a gene encoding transferrin receptor which is functionally disabled, such as by insertional mutagenesis. The Haemophilus strain may be one that has been attenuated and the attenuated strain may comprise the vector for delivery of transferrin receptor. As mentioned above, one aspect of the invention provides novel Tbp1 or Tbp2 protein of a strain of Haemophilus, preferably a strain of Haemophilus influenzae, which is isolated and purified and free from the other. A yet further aspect of the present invention provides a method for producing such proteins. Accordingly, in this yet further aspect, the present invention provides a method of producing an isolated and purified Tbp1 or Tbp2 protein of a strain of Haemophilus, comprising the steps of (a) providing a recombinant host expressing, in inclusion bodies, Tbp1 or Tbp2 protein, but not both; (b) growing the host to provide a cell mass; (c) disrupting the cell mass to provide a cell lysate; (d) fractionating the cell lysate to provide a first supernatant and a first pellet, the first supernatant comprising substantially a large proportion of soluble host proteins; (e) separating the first supernatant from the first pellet; (f) selectively extracting the first pellet to remove substantially all soluble host proteins and host membrane proteins therefrom to provide a second supernatant and an extracted pellet containing the inclusion bodies; (g) separating the second supernatant from the extracted pellet; (h) solubilizing the extracted pellet to provide a solubilized extract; and (i) fractionating the solubilized extract to provide a Tbp1 or Tbp2 protein containing fraction. The cell lysate may be fractionated to provide the first supernatant and first pellet may be effected by at least one detergent extraction. The solubilized extract may be fractionated by gel filtration to provide the Tbp1 or Tbp2 protein containing fraction, which may be subsequently dialyzed to remove at least the detergent and provide a further purified solution of Tbp1 or Tbp2 protein. BRIEF DESCRIPTION OF DRAWINGS The present invention will be further understood from the following description with reference to the drawings, in which: FIG. 1A shows the restriction map of two plasmid clones (pBHT1 and pBHT2) of the transferrin receptor operon of Haemophilus influenzae type b strain DL63. FIG. 1B shows the restriction map of clones S-4368-3-3 and JB-901-5-3 containing TfR genes from H. influenzae type b strain Eagan. FIG. 1C shows the restriction map of clone DS-712-1-3 containing the transferrin receptor gene from H. influenzae type b strain MinnA. FIG. 1D shows the restriction map of clone JB-1042-7-6 containing the transferrin receptor gene from the non-typable H. influenzae strain PAK 12085. FIG. 2 illustrates the organization and restriction maps of the cloned Tbp1 and Tbp2 genes of identified strains and the genetic organization of the TfR operon with two genes (tbp1 and tbp2) in tandem forming an operon under the transcriptional regulation of a single promoter and also depicts the 3.0 kb DNA fragment of pBHIT2 used to probe libraries for TfR genes from the Haemophilus strains. FIGS. 3A to 3Q show the nucleotide sequences of the transferrin receptor genes (SEQ ID NO: 1) and their deduced amino acid sequences (SEQ ID NO: 5--Tbp1 and SEQ ID NO: 6--Tbp2) from H. influenzae type b, strain DL63. The underlined amino acid sequences correspond to peptides of Tbp1 identified by amino acid sequencing. The putative signal sequences are indicated by double overlining and correspond to residues 1 to 17 for Tbp2 and 1 to 23 for Tbp1. FIGS. 4A to 4Q show the nucleotide sequences of the transferrin receptor genes (SEQ ID NO: 2) and their deduced amino acid sequences (SEQ ID NO: 7--Tbp1 and SEQ ID NO: 8--Tbp2) from H. influenzae type b strain Eagan. Putative -35, -10 aand ribosomal binding site sequences are overlined. FIGS. 5A to 5Q show the nucleotide sequences of the transferrin receptor genes (SEQ ID NO: 3) and their deduced amino acid sequences (SEQ ID NO: 9--Tbp1 and SEQ ID NO: 10--Tbp2) from H. influenzae type b strain MinnA. Putative -35, -10 and ribosomal binding site sequences are overlined. FIGS. 6A to 6Q show the nucleotide sequences of the transferrin receptor genes (SEQ ID NO: 4) and their deduced amino acid sequences (SEQ ID NO. 11--Tbp1 and SEQ ID NO. 12--Tbp2) from the non-typable H. influenzae strain PAK 12085. Putative -35, -10 and ribosomal binding site sequences are overlined. FIGS. 7A to 7N show the nucleotide sequences of the transferrin receptor genes (SEQ ID NO: 105) and their deduced amino acid sequences (SEQ ID NO. 106--Tbp1 and SEQ ID NO. 107--Tbp2) from the non-typable H. influenzae strain SB33. FIGS. 8A to 8G show the nucleotide sequence of the Tbp2 gene (SEQ ID NO: 108) and the deduced amino acid sequence (SEQ ID NO: 109--Tbp2) from non-typable strain H. influenzae strain SB12. FIGS. 9A to 9G show the nucleotide sequence of the Tbp2 gene (SEQ ID NO: 110) and the deduced amino acid sequence (SEQ ID NO: 111--Tbp2) from non-typable strain H. influenzae strain SB29. FIGS. 10A to 10G show the nucleotide sequence of the Tbp2 gene (SEQ ID NO: 112) and the deduced amino acid sequence (SEQ ID NO: 113--Tbp2) from non-typable strain H. influenzae strain SB30. FIGS. 11A to 11G show the nucleotide sequence of the Tbp2 gene (SEQ ID NO: 114) and the deduced amino acid sequence (SEQ ID NO: 115--Tbp2) from non-typable strain H. influenzae strain SB32. FIG. 12A shows the nucleotide sequences of the promoter regions and 5'-end of the tbp2 genes from H. influenzae strains Eagan (SEQ ID NO: 116), MinnA (SEQ ID NO: 117), PAK 12085 (SEQ ID NO: 118) and SB33 (SEQ ID NO: 119). The coding strand primer used to amplify tbp2 genes by PCR is underlined (SEQ ID NO: 120). FIG. 12B shows the nucleotide sequence of the intergenic region and 5'-end of the tbp1 genes from H. influenzae strains Eagan (SEQ ID NO: 121), MinnA (SEQ ID NO: 122), DL63 (SEQ ID NO: 123), PAK 12085 (SEQ ID NO: 124), SB12 (SEQ ID NO: 125), SB29 (SEQ ID NO: 126), SB30 (SEQ ID NO: 127), and SB32 (SEQ ID NO: 128). The non-coding strand primer used to amplify the tbp2 genes by PCR is underlined (SEQ ID NO: 129). FIG. 13 shows the agarose gel analysis of PCR amplified tbp2 genes from non-typable H. influenzae strains SB12, SB29, SB30, SB32 and SB33. Lane 1 is SB33, lane 2 is SB12, lane 3 is SB29, lane 4 is SB30, lane 5 is SB32. FIGS. 14A to 14C show a comparison of the amino acid sequences of Tbp1 from H. influenzae strains Eagan, DL63, PAK 12085 SB33 (SEQ ID NOS: 7, 5, 11 and 106), N. meningitidis strains B16B6 and M982 (SEQ ID NOS: 94 and 95), and N. gonorrhoeae strain FA19 (SEQ ID NO: 96). FIGS. 15A to 15D show a comparison of the amino acid sequence of Tbp2 from H. influenzae strains Eagan, DL63, PAK 12085, SB12, SB29, SB30 and SB32 (SEQ ID NOS: 8, 6, 12, 109, 110, 112, 114), N. meningitidis strains B16B6 and M982 (SEQ ID NOS: 97 and 98), N. gonorrhoeae strain FA19, and Actinobacillus pleuropneumoniae strains AP205 and AP37 (SEQ ID NOS: 99 and 100). FIGS. 16A' and 16A" show the predicted secondary structure of H. influenzae Tbp1 protein and FIGS. 16B' and 16B" show the predicted secondary structure of H. influenzae Tbp2 protein. FIG. 17 shows the construction scheme of plasmid JB-1468-29 which expresses H. influenzae type b Eagan Tbp1 from E. coli. FIG. 18 shows the construction scheme of plasmid JB-1424-2-8 which expresses H. influenzae type b Eagan Tbp2 from E. coli. FIG. 19 shows the oligonucleotide pairs (SEQ ID NOS: 130, 131) used to construct plasmid JB-1424-2-8. FIGS. 20A and 20B show the sequence of oligonucleotide pairs A (SEQ ID NOS: 86, 87), B (SEQ ID NOS: 88, 89), C (SEQ ID NOS: 90, 91) and D (SEQ ID NOS: 92, 93) for constructing Tbp1 and Tbp2 expression plasmids. FIG. 21 shows the construction scheme of plasmid JB-1600-1 which expresses H. influenzae strain SB12 Tbp2 from E. coli. FIG. 22 shows SDS-PAGE gels of products from the expression of Haemophilus type b Eagan Tbp1 protein, Eagan Tbp2 protein, and non-typable H. influenzae SB12 Tbp2 protein from E. coli. Lane 1, JB-1476-2-1 (T7/Eagan Tbp1) at t.sub.o ; lane 2, JB-1476-2-1 at t=4 h induction; lane 3, molecular weight markers of 200 kDa, 116 kDa, 97.4 kDa, 66 kDa, 45 kDa and 31 kDa; lane 4, JB-1437-4-1 (T7/Eagan Tbp2) at t.sub.o ; lane 5, JB-1437-4-1 at t=4 h induction; lane 6, JB-1607-1-1 (T7/SB12 Tbp2) at t.sub.o ; lane 7, JB-1607-1-1 at t=4 h induction. FIG. 23 shows a purification scheme for recombinant Tbp1 and Tbp2 expressed from E. coli. FIG. 24, comprising Panels A and B, shows an analysis of the purity of recombinant Tbp1 (Panel A) and Tbp2 (Panel B) purified by the scheme of FIG. 23. Lane 1 contains molecular weight size markers (106, 80, 49.5, 32.5, 27.5 and 18.5 kDa), Lane 2 is E. coli whole cell lysate. Lane 3 is solubilized inclusion bodies. Lane 4 is purified Tbp1 or Tbp2. FIGS. 25A and 25B show the immunogenicity of rTbp1 (upper panel) and rTbp2 (lower panel) in mice. FIG. 26 shows the reactivity of anti-Eagan rTbp1 antisera with various H. influenzae strains on a Western blot. Lane 1, BL21/DE3; lane 2, SB12-EDDA; lane 3, SB12 +EDDA; lane 4, SB29 -EDDA; lane 5, SB29 +EDDA; lane 6, SB33 -EDDA; lane 7, SB33 +EDDA; lane 8, Eagan -EDDA; lane 9, Eagan +EDDA; lane 10, B. catarrhalis 4223 -EDDA; lane 11, B. catarrhalis 4223 +EDDA; lane 12, N. meningitidis 608 -EDDA; lane 13, N. meningitidis 608 +EDDA; lane 14, induced JB-1476-2-1 expressing recombinant Eagan Tbp1; lane 15, molecular weight markers. Specific .about.95 kDa bands reacted with the anti-Tbp1 antisera in lanes 3, 4, 5, 7, 8 and 9, corresponding to H. influenzae strains SB12, SB29, SB33 and Eagan; .about.110 kDa bands in lanes 10 and 11, corresponding to B. catarrhalis strain 4223; and .about.80 kDa bands in lanes 12 and 13, corresponding to N. meningitidis 608. FIG. 27 shows the reactivity of anti-Eagan rTbp2 antisera with various H. influenzae strains on a Western blots. Lane 1, molecular weight markers; lane 2, induced JB-1437-4-1 expressing recombinant Eagan Tbp2; lane 3, SB12-EDDA; lane 4, SB12 +EDDA; lane 5, SB29 -EDDA; lane 6, SB29 +EDDA; lane 7, SB30 -EDDA; lane 8, SB30 +EDDA; lane 9, SB32 -EDDA; lane 10, SB33-EDDA; lane 11, SB33 +EDDA; lane 12, PAK -EDDA; lane 13, PAK +EDDA; lane 14, Eagan -EDDA; lane 15, Eagan +EDDA. Specific bands of 60-70 kDa were reactive with the anti-Tbp2 antisera in lanes, 3, 6, 7, 8, 13, 14 and 15, i.e. strains SB12, SB29, SB30, PAK and Eagan. FIG. 28 shows the construction of plasmids pUHIT1KFH and pUHIT1KFP used to generate strains of H. influenzae that do not produce transferrin receptor. FIG. 29 shows the construction of plasmids encoding chimeric polioviruses expressing an epitope derived from transferrin receptor protein that is conserved among bacteria that produce transferrin receptor protein. FIG. 30, comprising Panels A, B and C, is a Western blot showing the reactivity of antisera produced by immunization of rabbits with poliovirus chimeras expressing an epitope derived from transferrin receptor protein that is conserved among bacteria that produce transferrin receptor protein. Panel A shows a Coomassie Brilliant Blue-stained gel showing purified recombinant Tbp2 from H. influenzae strain SB12 expressed in E. coli (lane 1), purified Tbp2 from Branhamella catarrhalis strain 4223 (lane 2), a whole cell lysate of iron-limited B. catarrhalis strain 4223 (lane 3), a whole cell lysate of E. coli JM109 grown under non-iron limited conditions (lane 5). Panel B shows results of a Western blot of a replicate gel using a pool of the sera collected on day 27 from rabbits immunised with PV1TBP2A (rabbits 40, 41 and 42). Panel C shows the results for a pool of prebleed sera from the same, which displayed minimal specific reactivity. FIGS. 31A and 31B illustrate a number of truncated analogues of transferrin receptor protein Tbp2 of the Eagan strain. On the Figure, there are identified a number of clones which contain the nucleic acid molecules encoding the respective truncated analogs (The encoding nucleic molecule for the Tbp2 protein is shown in FIG. 4). The specific clones and the SEQ ID nos. for the encoded truncated Tbp2 analogs are contained in Table 8. FIG. 32A shows SDS PAGE analysis of truncated Tbp2 proteins while FIG. 32B the binding of truncated Tbp2 proteins to transferrin. In some of the above Figures, the following abbreviations have been used to designate particular site specific restriction endonucleases: R, Eco RI; Ps, Pst I; H, Hind III; Bg, Bgl II; Nde, Nde I; Ear, Ear I; and Sau, Sau3A I. In FIG. 28, the following abbreviations have been used to designate particular site specific restriction endonucleases: A, Acc I; B Bam HI; E, Eco RI; O, Xho I; H, Hind III; Ps, Pst I; V, Eco RV: X, Xba I, G, Bgl II; S, Sal I; K, Kpn I; and S*, Sac I. GENERAL DESCRIPTION OF THE INVENTION Any Haemophilus strain may be conveniently used to provide the purified and isolated nucleic acid which may be in the form of DNA molecules, comprising at least a portion of the nucleic acid coding for a transferrin receptor as typified by embodiments of the present invention. Such strains are generally available from clinical sources and from bacterial culture collections, such as the American Type Culture Collection. According to an aspect of the invention, the transferrin receptor protein may be isolated from Haemophilus strains by the methods described by Schryvers (1989), Ogunnaviwo and Schryvers (1992) and U.S. Pat. No. 5,141,743, the subject matter of which is hereby incorporated by reference. Although the details of an appropriate process are provided in U.S. Pat. No. 5,141,743, a brief summary of such process is as follows. Isolation of transferrin receptor is achieved by isolating a membrane fraction from a bacterial strain expressing transferrin binding activity and purifying the transferrin receptor by an affinity method involving the sequential steps of prebinding of tranferrin to the transferrin receptor in the membrane fraction, solubilising the membrane, immobilising the transferrin and separating the transferrin receptor from the immobilised transferrin. Alternatively, the receptor proteins may be isolated by a modification of the above method in which the prebinding step is avoided and a high concentration of salt is included in the solubilization buffer to allow direct isolation with immobilized transferrin as described in Ogunnariwo and Schryvers (1992). In this application, the term "transferrin receptor" is used to define a family of Tbp1 and/or Tbp2 proteins which includes those having variations in their amino acid sequences including those naturally occurring in various strains of, for example, Haemophilus. Other bacterial sources of transferrin receptor include, but are not limited to, species of Neisseria, Branhamella, Pasteurella and Actinobacillus. Some, if not all, of these bacteria contain both Tbp1 and Tbp2. The purified and isolated DNA molecules comprising at least a portion coding for transferrin receptor of the present invention also include those encoding functional analogs of transferrin receptor. In this application, a first protein or peptide is a "functional analog" of a second protein if the first protein is immunologically related to and/or has the same function as the second protein or peptide. The functional analog may be, for example, a fragment of the protein, such as those shown in FIG. 31, or a substitution, addition or deletion mutant thereof. In one particular embodiment, the transferrin receptor was isolated from H. influenzae type b strain DL63 and purified by affinity chromatography methods, as described by Schryvers (1989), Ogunnariwo and Schryvers (1992) and in U.S. Pat. No. 5,141,743. The isolated and purified transferrin receptor was used to generate anti-TfR antisera in rabbits. Chromosomal DNA from H. influenzae type b strain DL63 was mechanically sheared, EcoRI linkers added, and a .lambda.ZAP expression library constructed. The library was screened with the anti-TfR rabbit antisera and two positive clones (pBHIT1 and pBHIT2) were obtained which had overlapping restriction maps (FIG. 1A and FIG. 2). The clones were sequenced and two large open reading frames were identified (FIG. 2). The nucleotide sequences of the transferrin receptor genes Tbp1 and Tbp2 (SEQ ID NO: 1) from H. influenzae DL63 and their deduced amino acid sequences (SEQ ID NO: 5--Tbp1 and SEQ ID NO: 6--Tbp2) are shown in FIG. 3. The sequence analysis showed the TfR operon to consist of two genes (Tbp1 and Tbp2) arranged in tandem and transcribed from a single promoter (as particularly shown in FIG. 2 and FIG. 3). The Tbp2 protein tends to vary in molecular weight depending on the species whereas the Tbp1 protein tends to have a more consistent molecular weight with some variability across the various bacteria which have TfR genes. The molecular weight of Tbp1 is usually in the range of 94 to 106,000 whereas the molecular weight of Tbp2 varies considerably from 58 to 98 000. Amino acid sequencing of the N-termini and cyanogen bromide fragments of transferrin receptor from H. influenzae DL63 was performed. The N-terminus of Tbp2 was blocked but amino acid sequences were identified by sequencing of Tbp1 and are indicated by underlining within the protein sequence of FIG. 3. These peptide sequences are Glu Thr Gln Ser Ile Lys Asp Thr Lys Glu Ala Ile Ser Ser Glu Val Asp Thr (as shown in FIG. 3, SEQ ID NO: 101) and Leu Gln Leu Asn Leu Glu Lys Lys Ile Gln Gln Asn Trp Leu Thr His Gln Ile Ala Phe (as shown in FIG. 3; SEQ ID NO: 102). The signal sequence of Tbp1 and the putative signal sequence of Tbp2 are indicated by double overligning in FIG. 3. The putative signal sequence for Tbp1 is Met Thr Lys Lys Pro Tyr Phe Arg Leu Ser Ile Ile Ser Cys Leu Leu Ile Ser Cys Tyr Val Lys Ala (SEQ ID NO: 103). The putative signal sequence for Tbp2 is Met Lys Ser Val Pro Leu Ile Ser Gly Gly Leu Ser Phe Leu Leu Ser Ala (SEQ ID NO: 104). The derived amino acid sequence of the N-terminal region of Tbp2 indicates that it is a lipoprotein. Chromosomal DNA from H. influenzae type b strain Eagan was prepared and libraries were generated. The first library was constructed from DNA partially digested with Sau3A I, size-fractionated for -5-10 kb fragments, and cloned into a pUC-based plasmid. The second library was constructed from EcoRI- restricted chromosomal DNA fragments cloned into .lambda.ZAP. Both libraries were probed with a 5'-fragment of the pBHIT clone as shown in FIG. 2 and partial clones of the TfR genes of H. influenzae Eagan termed S-4368-3-3 and JB-901-5-3 were obtained. Thus, referring to FIGS. 1B and 2, there is illustrated according to further aspects of the present invention, plasmid clones S-4368-3-3 and JB-901-5-3 encoding Tbp1 and Tbp2 from H. influenzae type b strain Eagan. The DNA sequences of the Tbp1 and Tbp2 genes (SEQ ID NO: 2) from H. influenzae type b strain Eagan and their deduced amino acid sequences (SEQ ID NOS: 7 and 8) are shown in FIG. 4 with the Tbp2 sequence being the first gene in the operon. In FIG. 4, putative -35, -10 and ribosomal binding site sequences are overlined. Chromosomal DNA from H. influenzae type b strain MinnA was prepared and the DNA partially digested with Sau3A I, size-fractionated for 10-20 kb fragments, and cloned into the BamHI site of EMBL3. The library was probed with the 5'-fragment of the pBHIT clone (FIG. 2) and a full-length clone encoding TfR (DS-712-1-3) was obtained. Referring to FIGS. 1C and 2, there is illustrated according to additional aspects of the present invention, plasmid clone DS 712-1-3 encoding Tbp1 and Tbp2 from H. influenzae type b strain MinnA. The DNA sequences of Tbp1 and Tbp2 (SEQ ID NO: 3) and their deduced amino acid sequences (SEQ ID NO: 9--Tbp1 and SEQ ID NO: 10--Tbp2) from H. influenzae type b strain MinnA are shown in FIG. 5 where the Tbp2 sequence is first in the operon. In FIG. 5, Putative -35, -10 and ribosomal binding site sequences are overlined. Chromosomal DNA from the non-typable H. influenzae strain PAK 12085 was prepared. The DNA was partially digested with Sau3A I, size-fractionated for 10-20 kb fragments, and cloned into the BamH I site of EMBL3. The library was probed with the fragments of the pBHIT clone (FIG. 2) and a full-length clone encoding TfR (JB-1042-7-6) was obtained. The restriction map of clone JB-1042-7-6 is shown in FIGS. 1D and 2 and the nucleotide sequences of the Tbp1 and Tbp2 genes (SEQ ID NO: 4) from H. influenzae PAK 12085 and their deduced amino acid sequences are shown in FIG. 6 (SEQ ID NOS: 11, 12), with the Tbp2 sequence first. In FIG. 6, Putative -35, -10 and ribosomal binding site sequences are overlined. Chromosomal DNA from the otitis-media derived non-typable H. influenzae strain SB33 was prepared. The DNA was partially digested with Sau3A I, size-fractionated for 10-20 kb fragments, and cloned into the BamH I site of EMBL3. The library was probed with the fragments of the pBHIT clone (FIG. 2) and a full-length clone encoding TfR (JB-1031-2-9) was obtained. The restriction map of clone JB-1031-2-9 is shown in FIG. 2 and the nucleotide sequences of the Tbp1 and Tbp2 genes (SEQ ID NO: 4) from H. influenzae SB33 and their deduced amino acid sequences are shown in FIG. 7 (SEQ ID NOS: 11, 12), with the Tbp2 sequence first. The SB33 tbp2 gene was found to have a single base deletion which resulted in a frame-shift at residue 126 and premature truncation of the resulting protein at residue 168. PCR amplification of the tbp2 genes from otitis media-derived NTHi strains SB12, SB29, SB30 and SB32 was performed and the genes sequenced. The nucleotide sequence of the tbp2 genes from non-typable H. influenzae strains SB12 (SEQ ID NO: 105), SB29 (SEQ ID NO: 108), SB30 (SEQ ID NO: 110) and SB32 (SEQ ID NO: 112) are shown in FIGS. 8, 9, 10 and 11 respectively. All of the amplified tbp2 genes were found to encode full-length Tbp2 proteins indicating that the defective tbp2 gene of strain SB33 was atypical. The three H. influenzae b strains all had identical short intergenic sequences of only 13 bp between tbp2 and tbp1, but the NTHi strains PAK 12085 and SB33 had longer intergenic sequences of 27 bp (FIG. 12). Strain SB12 had a 13 bp intergenic sequence identical to that found in the H. influenzae b strains while strains SB29, SB30 and SB32 contained longer intergenic sequences (27-30 bp) as found in the other NTHi strains PAK 12085 and SB33 (FIG. 2B). All nine strains have a common core conserved 13 bp sequence between their tbp2 and tbp1 genes. A pentapeptide sequence near the amino terminus of H. influenzae Tbp1 was identified (FIG. 12) which is similar to the TonB box. The tonB gene of H. influenzae has been recently cloned and sequenced (Jarosik et al., 1994). The amino acid sequences of Tbp1 from H. influenzae strains Eagan/MinnA, DL63, PAK 12085 and SB33 strains are compared in FIG. 14. The Tbp1 proteins of Eagan and MinnA are identical and 912 amino acids in length, that of DL63 has 914 residues, that of PAK 12085 has 914 residues, and that of SB33 has 911 residues. The H. influenzae Tbp1 proteins are highly conserved with 95-100% sequence identity. The amino acid sequences of Tbp2 from H. influenzae strains Eagan/MinnA, DL63, PAK 12085 SB12, SB29, Sb30 and Sb32 are compared in FIG. 15. The Tbp2 proteins of Eagan and MinnA are identical and contain 660 amino acids, that of DL63 has 644 residues, and that of PAK 12085 has 654 residues. There is a single base deletion in the SB33 tbp2 gene which results in a frame-shift at residue 126 and premature trunction of the resulting protein at residue 168. The missing base was confirmed by direct sequencing of PCR amplified chromosomal DNA. With the exception of Eagan and MinnA which are identical, the Tbp2 protein sequences are less conserved with only 66-70% identity, but there are several short segments of conserved sequence which can be identified in FIG. 15. The PCR amplified tbp2 genes from strains SB12, SB29, SB30 and SB32 were all found to encode full-length Tbp2 proteins. There was sequence and size heterogeneity amongst the deduced Tbp2 proteins wherein SB12 had 648 amino acids, SB29 had 631 residues, SB30 had 630 residues and SB32 had 631 residues. Putative secondary structures of Eagan Tbp1 and Tbp2 were determined (FIGS. 16A and 16B). Both proteins have several transmembrane domains, with Tbp1 traversing the membrane 20 times and Tbp2 crossing it 12 times. Three exposed conserved epitopes were identified in the Tbp1 amino-terminal region (DNEVTGLGK--SEQ ID NO: 43, EQVLN/DIRDLTRYD--SEQ ID NOS: 139 and 140, and GAINEIEYENVKAVEISK--SEQ ID NO: 141) and one in the C-terminal region (GI/VYNLF/LNYRYVTWE--SEQ ID NOS: 142 and 143). Only three small conserved regions can be identified within the Tbp2 proteins of the human pathogens: CS/LGGG(G)SFD--SEQ ID NOS: 75, 144 and 145 at the N-terminal, LE/SGGFY/FGP--SEQ ID NOS: 74 and 146 located internally, and VVFGAR/K--SEQ ID NOS: 83 and 84 at the C-terminus. The discovery that the Tbp2 amino acid sequence varies between strains of Haemophilus allows for the grouping of Haemophilus into sub-groups defined by the same Tbp2 amino acid sequence. This discovery allows the rational selection of a minimal number of Tbp1 and/or Tbp2 sequences or synthetic peptides representing epitopes shared by such subtypes within strains of Haemophilus to be used in immunogenic compositions for, for example, immunization against the diseases caused by Haemophilus and other bacteria that produce transferrin receptor with sequence similarities to Tbp1 and Tbp2 from Haemophilus species. Thus, a minimal number of transferrin receptor, analogs, fragments, and/or peptides, may be used to immunize against many or all strains of Haemophilus and other bacterial pathogens that produce transferrin receptor. Furthermore, the amino acid sequences of the transferrin receptor from a range of bacterial pathogens (H. influenzae type b, non-typable H. influenzae, Neisseria meningitidis, Neisseria gonorrhoeae and Actinobacillus (Haemophilus) pleuropneumoniae) were compared as shown in FIGS. 14 and 15. This analysis revealed regions of Tbp1 and Tbp2 which are conserved between all of these bacteria. Some of such conserved sequences are contained in peptides in Tables 2 and 3. In particular the sequences DNEVTGLGK (SEQ ID: 43), EQVLNIRDLTRYDPGI (SEQ ID NO: 44), EQVLNIRDLTRYDPGISVVEQG RGASSGYSIRGMD (SEQ ID NO: 45), GAINEIEYENVKAVEISKG (SEQ ID NO: 46) and GALAGSV (SEQ ID NO: 47) are conserved in Tbp1 (Table 1 and FIG. 14). Particular conserved sequences in Tbp2 include LEGGFYGP (SEQ ID NO: 74), CSGGGSFD (SEQ ID NO: 75), YVYSGL (SEQ ID NO: 76), CCSNLSYVKFG (SEQ ID NO: 77), FLLGHRT (SEQ ID NO: 78), EFNVOF (SEQ ID NO: 79), NAFTGTA (SEQ ID NO: 80), VNGAFYG (SEQ ID NO: 81), ELGGYF (SEQ ID NO: 82), VVFGAR (SEQ ID NO: 83) and VVFGAK (SEQ ID NO: 84) (Table 2 and FIG. 15). The discovery of conserved sequences within the transferrin receptor of a range of bacterial pathogens allows the selection of a minimal number of antigens having particular amino acid sequences (including in the form of synthetic peptides) to immunize against the disease caused by pathogens that have transferrin receptors. Such bacteria in addition to those recited above include other species of Neisseria, such as Neisseria gonorrhoeae, and Branhamella, including Branhamella catarrhalis. Such conserved amino acid sequences among many bacterial pathogens permits the generation of TfR specific antibodies, including monoclonal antibodies, that recognize most if not all transferrin receptors. Antiserum was raised against peptides corresponding to conserved portions of the transferrin receptor. This antiserum recognized the transferrin receptor in Branhamella catarrhalis. Such antisera are useful for the detection and neutralization of most if not all bacteria that produce TfR protein and are also useful for passive immunization against the diseases caused by such pathogens. Diagnostic assays and kits using such conserved amino acid sequences are useful to detect many if not all bacteria that produce transferrin receptor. Epitopes containing the afore-mentioned amino acid sequences can be delivered to cells of the immune system by the use of synthetic peptides containing such sequences, or by the use of live vectors expressing such sequencies, or by the direct administration of the nucleic acid molecules encoding the amino acid sequence. Some peptides containing conserved amino acid sequences within the Tbp1 proteins of H. influenzae type b strains Eagan, Minna, DL63 and the nontypable strain PAK 12085 are shown in Table 2. Antibodies to some of these peptides were raised in guinea pigs (Table 4). Peptides containing conserved amino acid sequences within the Tbp2 proteins of H. influenzae type b strains Eagan, Minn A, DL 63 and the nontypable strain PAK 12085 are shown in Table 3. Antibodies to some of these peptides were raised in guinea pigs (Table 4). The coding sequences of the Tbp1 and Tbp2 genes may be cloned into appropriate expression vectors to produce recombinant proteins. Recombinant Tbp1 and Tbp2 were expressed from E. coli using the T7 expression system. The tbp1 gene encoding the mature Eagan Tbp1 protein was clined in-frame behind the T7 promoter generating plasmid JB-1468-29, as shown in FIG. 17. When introduced into Bl21/DE3 cells and induced with IPTG or lactose, Eagan Tbp1 protein was expressed as shown in FIG. 22. The tbp2 gene encoding the mature Tbp2 protein was cloned in-frame behind the T7 promoter generating plasmid JB-1424-2-8 as shown in FIG. 18. When introduced into E. coli cells and induced as above, Tbp2 protein was expressed as shown in FIG. 22. The tbp2 gene from strain TTHi SB12 was amplied by PCR. The resultant amplified DNA contains the authentic M. influenzae tbp2 signal sequence before the mature protein, the SB12 tbp2 gene encoding the signal sequence and the mature protein was cloned into the pT7-7 expression system as shown in FIG. 21. When the resultant plasmid (JB-1600-1) was introduced into E. coli 21/DE3 cells and induced, SB12 Tbp2 was expressed, as shown in FIG. 22. Recombinant proteins Tbp1 and Tbp2 produced in E. coli as inclusion bodies were purified by the scheme shown in FIG. 23. The purified proteins were at least about 70% pure as shown in FIG. 24. Immunogenicity studies were performed in mice with the purified recombinant Tbp1 and Tbp2 proteins. Both proteins elicited a good immune response in mice at 3-10 .mu.g does (FIG. 25). Antisera raised to recombinant Tbp1 or Tbp2 derived from one H. influenzae strain are cross-reactive with other strains, making these potentially useful diagnostic reagents (FIGS. 26 and 27). Plasmids pUHITIKFH and pUHITKFP shown in FIG. 28, contain a selectable antibiotic resistance marker cloned within the transferrin receptor operon and were constructed to insertionally inactive the transferrin receptor operon. These plasmids were used to transform Haemophilus to generate strains that do not produce transferrin receptor Tbp1 and/or Tbp2 as described in Example 19. Such strains are useful as negative controls (since they do not produce TfR) in in vitro and in vivo detection and diagnostic embodiments. Such strains are also expected to be attenuator for in vivo growth and are useful as live vaccines to provide protection against diseases caused by Haemophilus. As discussed above, epitopes of transferrin receptor proteins can be delivered to cells of the immune system by the use of live vectors expressing such amino acid sequences and the live vector may be poliovirus. Referring to FIG. 29 there is illustrated the construction of hybrid polioviruses expressing an epitope of transferrin receptor protein including the conserved epitope from Tbp2 LEGGFYGP (SEQ ID NO: 74). Such viruses were recognized by antibodies raised against a peptide incorporating the amino acid sequence LEGGFYGP (SEQ ID NO: 74) (Table 5) indicating that the viruses expressed this sequence in an antigenically recognisable form. PV1TBP2A and PV1TBP2B were also neutralized by rabbit antisera raised against H. influenza strain DL63 tbp2, indicating that at least these two viruses expressed the sequence in a form recognisable to antiboides raised against the protein. All viruses were neutralisable by anti-PV1 sera, indicating that the changes in polio neutralization antigenic site I had not significantly affected other antigenic sites on the viruses. Furthermore, rabbit antiserum produced by immunization with poliovirus chimera Pv1TBP2A or PV1TBP2B recognized a peptide incorporating the amino acid sequence LEGGFYGP (SEQ ID NO: 74). This indicates that the sequences expressed by PV1TB2A and PV1TBP2B are immunogenic and elicit antiboides capable of recognizing the same sequence in the context of a synthetic peptide. Referring to FIG. 30, panel A shows an SDS PAGE gel showing purified recombinant tbp2 from H. influenzae strain SB12 expressed in E. coli (lane 1), tbp2 from Branhamella catarrhalis strain 4223 (lane 2), a whole cell lysate of iron-limited B. cattarrhalis strain 4223 (land 3), a whole cell lysate of iron-limited E. coli JM109 (lane 4) , and a whole cells lysate of E. coli JM109 grown under non-iron limited conditions (lane 5). Panel B shows results of a Western blot of a replicate gel using a pool of sera from rabbits immunized with PV1TBP2A. There was a strong reaction with the purified transferrin-binding proteins in lanes 1 and 2, and with a similar sized band in lane 3. There was no significant reaction with any E. coli proteins (lanes 4 and 5). Panel C shows the results for a pool of prebleed sera from the same rabbits, which displayed minimal specific reactivity. These results show that PV1TBP2A is able to induce antisera specific for transferrin binding proteins from H. influenzae and B. catarrhalis, and that the antisera can distinguish B. catarrhalis from E. coli, which does not express an equivalent protein. Guinea pig anti-Eagan rTbp1, anti-Eagan rTbp2, and anti-Sb12 rTbp2 antisera were used to screen a panel of H. influenzae strains for antigenic conservation of the Tbp1 and Tbp2 proteins. Of 33 strains screened by Western blot with anti-Eagan rTbp1 antisera, all had a reactive band of -100 kDa. Of 89 strains screened by Western blot with anti-Eagan rTbp2 antisera, 85 had a reactive band of 60-90 kDa. Of 86 strains screened by Western blot with anti-Sb12 rTbp2 antisera, 82 had a reactive band of 60-90 kDa. Only one strain was not recognized by either anti-Eagan rTbp2 or anti-Sb12 rTbp2 antisera, and that was NTHi strain SB33 which as a defective tbpB gene. These data indicate that transferrin receptor proteins are highly conserved in strains of H. influenzae and support the use of these proteins as antigens and in immunogenic compositions, including vaccines, for immunization against disease cause by H. influenzae and diagnosis thereof. The infant rat model of bacteremia (Loeb et al, 1987) was used to assess the protective ability of anti-Eagan rTbp1 and anti-Eagan rTbp2 antisers. Anti-Eagan rTbp1 antisera raised in either rabbits or guinea pigs was not protective in this model but anti-Eagan rTbp2 antisera raised in rabbits or guinea pigs was protective (Table 7). These data indicate the use for rTbp2 proteins as protective antigens against disease caused by H. influenzae. The chinchilla model of otitis media (Barenkamp et al, 1986) was used to assess the protective ability of Sb12 rTbp2. Data indicated that compared with the control group, the immunized animals has less severe disease. In further embodiments, there is provided a number of truncated analogues at transferrin receptor protein Tbp2 as shown in Table 8 and FIG. 31 below, and nucleic acid molecules encoding the same. Some of such truncated analogues are highly expressed in recombinant expression systems (such as E. coli) and represent appropriate antisera and immunogens in diagnostic and vaccination embodiments of the invention. The purified and isolated DNA molecules comprising at least a portion coding for a transferrin receptor of a species of Haemophilus typified by the embodiments described herein are advantageous as: nucleic acid probes for the specific identification of Haemophilus strains in vitro or in vivo. the products encoded by the DNA molecules are useful as diagnostic reagents, antigens for the production of Haemophilus-specific antisera, for vaccination against the diseases caused by species of Haemophilus and (for example) detecting infection by Haemophilus. peptides corresponding to portions of the transferrin receptor as typified by the embodiments described herein are advantageous as diagnostic reagents, antigens for the production of Haemophilus-specific antisera, for vaccination against the diseases caused by species of Haemophilus and (for example) for detecting infection by Haemophilus. The transferrin receptor encoded by the nucleic acid molecules of the present invention, fragments and analogs thereof, and peptides containing sequences corresponding to portions of the transferrin receptor that are conserved between various isolates of Haemophilus and other bacteria that produce transferrin receptor, are useful in diagnosis of and immunization against diseases caused by any bacterial strain that produces transferrin receptor. In particular, peptides containing the sequences LEGGFYGP are conserved in the transferrin receptor proteins of may bacterial pathogens that produce transferrin receptor and are appropriate for diagnosis of and immunization against diseases caused by bacteria that produce transferrin receptor. Such bacteria include but are not limited to species of Haemophilus, Neisseria (including N. meningitidis and N. gonorrhoeae) and Branhamella (including B. catarrhalis). It is clearly apparent to one skilled in the art, that the various embodiments of the present invention have many application in the fields of vaccination, diagnosis, treatment of, for example, Haemophilus infections, and infections with other bacterial pathogens that produce transferrin receptor and the generation of immunological reagents. A further non-limiting discussion of such uses is further presented below. 1. Vaccine Preparation and Use Immunogenic compositions, suitable to be used as vaccines, may be prepared from immunogenic transferrin receptor, analogs and fragments thereof and/or peptides as disclosed herein. The vaccine elicits an immune response which produces antiboides, including anti-transferrin receptor antibodies and antibodies that are opsonizing or bactericidal. Should the vaccinated subject be challenged by Haemophilus or other bacteria that produce a transferrin receptor, the antibodies bind to the transferrin receptor and thereby prevent access of the bacteria to an iron source which is required for visability. Furthermore, opsonizing or bactericicial anti-TfR antibodies may also provide protection by alternative mechanisms. Vaccines containing peptides are generally well known in the art, as exemplied by U.S. Pat. Nos. 4,601,903; 4,599,231; 4,599,230; and U.S. Pat. No. 4,596,792; all of which references are incorporated herein by reference. Immunogenic compositions including vaccines may be prepared as injectables, as liquid solution or emulsions. The transferrin receptor, analogs and fragments thereof and/or peptides may be mixed with pharmaceutically acceptable excipients which are compatabile with the transferrin receptor, fragments analogs or peptides. Such excipients may include, water, saline, dextrose, glycerol, ethanol, and combinations thereof. The immunogenic compositions and vaccines may further contain auxiliary substances such as wetting or emulsifying agents, pH buffering agents, or adjuvants to enhance the effectiveness of the vaccines. Immunogenic compositions and vaccines may be administered parenterally, by injection subcutaneously or intramuscularly. Alternatively, the immunogenic compositions formed according to the present invention, may be formulated and delivered in a manner to evoke an immune response at mucosal surfaces. Thus, the immunogenic composition may be administered to mucosal surfaces by, for example, the nasor or oral (intragastric) routes. The immunogenic composition may be provided in combination with a targeting molecule for delivery to specific cells of the immune system or to mucosal surfaces. Some such targeting molecules include strian B12 and fragments of bacterial toxins, as described in WO 92/17167 (Biotech Australia Pty. Ltd.), and monoclonal antibodies, as described in U.S. Pat. No. 5,194,254 (Barber et al). Alternatively, other modes of administration including suppositories and oral formulations may be desirable. For suppositories, binders and carries may include, for example, polyalkalene glycols or triglycerides. Oral formulations may include normally employed incipients such as, for example, pharmaceutical grades of saccarine, cellulose and magnesium carbonate. These compositions take the form of solutions, suspensions, tablets, pills, capsules, sustained release formulations or powders and contain 10-95% of the transferrin receptor, fragment analogs and/or peptides. The vaccines are administered in a manner compatible with the dosage formulation, and in such amount as will be therapeutically effective, protective and immunogenic. The quantity to be administered depends on the subject to be treated, including, for example, the capacity of the individual's immune system to synthesize antibodies, and if needed, to produce a cell-mediated immune response. Precise amounts of active ingredient required to be administered depend on the judgment of the practitioner. However, suitable dosage ranges are readily determinable by one skilled in the art and may be of the order of micrograms of the transferrin receptor, analogs and fragments thereof and/or peptides. Suitable regimes for initial administration and booster does are also variable, but may include an initial administration followed by subsequent administrations. The dosage of the vaccine may also depend on the route of administration and will vary according to the size of the host. The nucleic acid molecules encoding the transferrin receptor of the present invention may also be used directly for immunization by administration of the DNA directly, for example by injection for genetic immunization or by constructing a live vector such as Salmonella, BCG, adenovirus, poxvirus, vacccccinia or poliovirus. A discussion of some live vectors that have been used to carry heterologous antigens to the immune system are discussed in for example O'Hagan (1992). Processes for the direct injection of DNA into test subjects for genetic immunization are described in, for example, Ulmer et al., 1993. The use of peptides in vivo may first require their chemical modification since the peptides themselves may not have a sufficiently long serum and/or tissue half-life and/or sufficient immunogenicity. Such chemically modified peptides are referred to herein as "peptide analogs". The term "peptide analog" extends to any functional chemical equivalent of a peptide characterized by its increased stability and/or efficacy and immunogenicity in vivo or in vitro in respect of the practice of the invention. The term "peptide analog" is also used herein to extend to any amino acid derivative of the peptides as described herein. Peptide analogs contemplated herein are produced by procedures that include, but are not limited to, modifications to side chains, incorporation of unnatural amino acids and/or their derivatives during peptide synthesis and the use of cross-linkers constraint on the peptides or their analogs. Examples of side chain modifications contemplated by the present invention include modification of amino groups such as by reductive alkylation by reaction with an aldehyde followed by reduction with NaBH.sub.4 ; amidation with methylacetimidate; acetylation with acetic anhydride; carbamylation of aminio groups with cyanate; trinitrobenzylation of amino gropus with 2, 4, 6, trinitrobenzene sulfonic acid (TNBS); alkylation of amino groups with succinic anhydride and tetrahydrophthalic anhydride; and pyridoxylation of lysine with pyridoxal-5'-phosphate followed by reduction with NaBH.sub.4. The guanidino group of arginine residues may be modified by the formation of heterocyclic condensation products with reagents such as 2, 3-butanedione, phenylglyoxal and glyoxal. The carboxyl group may be modified by carbodiimide activation via o-acylisourea formation followed by subsequent derivatisation, for example, to a corresponding amide. Sulfhydryl groups may be modified by methods such as carboxymethylation with iodoacetic acid or iodoacetamide; performic acid oxidation to cysteic acid; formation of mixed disulphides with other thiol compounds; reaction with maleimide; maleic anhydride or other substituted maleimide; formation of mercurial derivates using 4-chloromercuribenzoate, 4-chloromercuriphenylsulfonic acid, phenylmercury chloride, 2-chloromercuric-4-nitrophenol and other mercurials; carbamylation with cyanate at alkaline pH. Tryptophan residues may be modified by, for example, oxidation with N-bromosuccinimde or alkylation of the indole ring with 2-hydroxy-5-nitrobenzyl bromide or sulphony halides. Tryosine residues may be altered by nitration with tetranitromethane to form a 3-nitrotyrosine derivative. Modification of the imidazole ring of a histidine residue may be accomplished by alkylation with iodoacetic acid derivatives or N-carbethoxylation with diethylpyrocarbonate. Examples of incorporating unnatural amino acids and derivatives during peptide synthesis include, but are not limited to, use of norleucine, 4-amino butyric acid, 4-amino-3-hydroxy -5-phenylpentanoic acid, 6-aminohexanoic acid-, t-butylglycine, norvaline, phenylglycine, ornithine, sarcosine, 4-amine-3-hydroxy-6-methylheptanoic. acid, 2-thienyl alanine and/or D-isomers of amino acids. Immunogenicity can be significantly improved in the antigens are co-administered with adjuvants, commonly used as an 0.05 to 1.0 percent solution in phosphate--buffered saline. Adjuvants enhance the immunogenicity of an antigen but are not necessarily immunogenic themselves. Adjuvants may act by retaining the antigen locally near the site of administration to produce a depot effect facilitating a slow, sustained release of antigen to cells of the immune system. Adjuvants can also attract cells of the immune system to an antigen depot and stimulate such cells to elicit immune responses. Immunostimulatory agents or adjuvants have been used for many years to improve the host immune responses to, for example, vaccines. Intrinsic adjuvants, such as lipopolysaccharides, normally are the components of the killed or attenuated bacteria used as vaccines. Extrinsic adjuvants are immunomodulators which are typically non-covalently linked to antigens and are formulated to enhance the heat immune responses. Thus, adjuvants have been identified that enhance the immune response to antigens delivered parenterally. Some of these adjuvants are toxic, however, and can cause undesirable side-effects, making them unsuitable for use in humans and many animals. Indeed, only aluminum hydroxide and aluminim phosphate (collectively commonly referred to as alum) are routinely used as adjuvants in human and veterinary vaccines. The efficacy of alum in increasing antibody responses to diptheria and tentanus toxoids is will established and, more recently, a HBsAg vaccine has been adjuvanted with alum. While the usefulness of alum is well established for some applications, it has limitations. For example, alum is ineffective for influenza vaccination and inconsistently elicits a cell mediated immune response. The antibodies elicited by alum-adjuvanted antigens are mainly of the IgG1 isotype in the mouse, with may not be optimal for protection by some vaccinal agents. A wide range of extrinsinc adjuvants can provoke potent immune response to antigens. These include saponins complexed to membrane protein antigens (immune stimulating complexes), pluronic polymers with mineral oil, killed mycobacteria and mineral oil, Freund's complete adjuvant, bacterial products, such as muramyl dipeptide (MDP) and lippolysaccharide (LPS), as well as lipid A, and liposomes. To efficiently induce humoral immune responses (HIR) and cell-mediate immunity (CMI), immunogens are emulsified in adjuvants. Many adjuvants are toxic, incuding granulomas, acute and chronic inflammations (Freund's complete adjuvant, FCA), cytolysis (saponins and pluronic polymers) and pyrogenicity, arthritis and anterior uveitis (LPS an dMDP). Although FCA is an excellent adjuvant and widely used in research, it is not licensed for use in human or veterinary vaccines because of its toxicity. Desirable characteristics of ideal adjuvants include: (1) lack of toxicity; (2) ability to stimulate a long-lasting immune response; (3) simplicity of manufacture and stability in long-term storage; (4) ability of elicit both CMI and HIR to antigens administered by various routes, if required; (5) synergy with other adjuvants; (6) capability of selectively interacting with population of antigen presenting cells (APC); (7) ability to specifically elicit appropriate T.sub.H 1 or T.sub.H 2 cell-specific immune responses; and (8) ability to selectively increase appropriate antibody lectype levels (for example, IGa) against antigens. U.S. Pat. No. 4,855,283 granted to Lockhoff et al on Aug. 8, 1989 which is incorporated herein by reference thereto teaches glycolipid analogues including N-glycoylamides, N-glycosylureas and N-glycosylcarbamates, each of which is substituted in the sugar residue by an amino acid, as immuno-modulators or adjuvants. Thus, Lockhoff et al. 1991 reported that N-glycolipid analogs displaying structural similarities to the naturally-occurring glycolipids, such as glycosphingolipids and glycoglycerolipids, are capable of eliciting strong immune responses in both herpes simplex virus vaccine and psueodorabies virus vaccine. Some glycolipids have been synthesized from long chain-alkylamines and fatty acids that are linked directly with the sugars through the anomeric carbon atoms, to mimic the functions of the naturally occurring lipid residues. U.S. Pat. No. 4,258,029 granted to Moloney, assigned to the assignee hereof and incorporated herein by reference thereto, teaches that octadecyl tyrosine hydrochloride (OTH) functions as an adjavant when complexed with tetanus toxoid and formalin inactivated type I, II and III poliomyelitis virus vaccine. Also, Nixon-George et al. 1990, reported that octadecyl esters of artomatic amino acids complexed with a recombinant hepatitis B surface antigen, enhanced the host immune responses against hepatitis B virus. Lipidation of synthetic peptides has also been used to increase their immunogenicity. Thus, Wiesmuller 1989, describes a peptide with a sequence homologous to a foot-and-mouth disease viral protein coupled to an adjuvant tripalmityl-a-glyceryl-cysteinylserylserine, being a synthetic analogue of the N-terminal part of the lipoprotein from Grm negative bacteria. Furthermore, Deres et al. 1989, reported in vivo priming of virus-specific cytotoxic T lymphocyte with synthetic lipopeptide vaccine which comprised of modified synthetic peptides derived from influenza virus nucleoprotein by linkage to a lipopeptide, N-palmityl-s-[2,3]-bis (palmitylx)-(2RS)-propyl-[R]-cysteine (TPC). 2. Immunoassays The transferrin receptor, analogs and fragments thereof and/or peptides of the present invention are useful as immunogens, as antigens in immunoassays including enzyme-linked immunosorbent assays (ELISA), RIAS and other non-enzyme linked antibody binding assays or procedures known in the art for the detection of anti-bacterial, Haemophilus, TfR and/or peptide antibodies. In ELISA assays, the transferrin receptor, analogs, fragments and/or peptides corresponding to portions of TfR protein are immobilized onto a selected surface, for example a surface capable of binding proteins or peptides such as the wells of a polystyrene microtiter plate. After washing to remove incompletely adsorbed transferrin receptor, analogs, fragments and/or peptides, a nonspecific protein such as a solution of bovine serum albumin (BSA) or casein that is known to be antigenically neutral with regard to the test sample may be bound to the selected surface. This allows for blocking of nonspecific adsorption sites on the immobilizing surface and thus reduces the background caused by nonspecific bindings of antisera onto the surface. Preferably, the selected peptides are from the conserved regions of Table 2 or Table 3 to enhance the cross-species is to be detected. In that event a polypeptide is selected which is unique to the TfR of that particular species. Normally, the peptides are in the range of 12 residues and up and preferably 14 to 30 residues. It is understood however, that a mixture of peptides may be used either as an immunogen in a vaccine or as a diagnostic agent. There may be circumstances where a mixture of peptides from the conserved regions and/or from the non-conserved regions are used to provide cross-species protection and/or diagnosis. In this instance, the mixture of peptide immunogens is commonly referred to as a "cocktail" preparation for use as a vaccine or diagnostic agent. The immobilizing surface is then contacted with a sample such as clinical or biological materials to be tested in a manner conductive to immune complex (antigen/antibody) formation. This may include diluting the sample with diluents such as BSA, bovine gamma globulin (BGG) and/or phosphate buffered saline (PBS)/Tween. The sample is then allowed to incubate for from 2 to 4hours, at temperatures such as of the order of 25.degree. C. to 37.degree. C. Following incubations, the sample-contacted surface is washed to remove non-immunocomplexed material. The washing procedure may include washing with a solution such as PBS/Tween, or a borate buffer. Following formation of specific immunocomplexes between the test sample and the bound transferrin receptor, analogs, fragments and/or peptides, and subsequent washing, the occurrence, and even amount, of immunocomplex formation may be determined by subjecting the immunocomplex to a second antibody having specificity for the first antibody. If the test sample is of human origin, the second antibody is an antibody having specificity for human immunoglobulins and in general IgG. To provide detecting means, the second antibody may have an associated activity such as an enzymatic activity that will generate, for example, a color development upon incubating with an appropriate chromogenic substrate. Quantification may then achieved by measuring the degree of color generation using, for example, a visible spectra spectrophotometer. 3. Use of Sequences as Hybridization Probes The nucleotide sequences of the present invention, comprising the sequence of the transferrin receptor gene, now allow for the identification and cloning of the transferrin receptor genese from any species of Haemophilus and other bacteria that have transferrin receptor genes. The nucleotide sequences comprising the sequence of the transferrin receptor genes of the present invention are useful for their ability to selectively form duplex molecules with complementary stretches of other TfR genes. Depending on the application, a variety of hybridization conditions may be employed to achieve varying degrees of selectivity of the probe toward the other TfR genes. For a high degree of selectivity, relatively stringent conditions are used to form the duplexes, such as low salt and/or high temperature conditoins, such as provided by 0.02M to 0.15M aNaCl at temperatures of between about 50.degree. C. to 70.degree. C. For some applications, less stringent hybridization conditions are required such as 0.15M to 0.9M salt at temperatures ranging from between about 20.degree. C. to 55.degree. C. Hybridization conditions can also be rendered more stringent by the addition of increasing amounts of formamide, to destabilize the hybrid duplex. Thus, particular hybridization conditions can be readily manipulated, and will generally be a method of choice depending on the desired results. In general, convenient hybridization temperatures in the presence of 50% formamide are: 42.degree. C. for a probe which is 95 to 100% homologous to the target fragment, 37.degree. C. for 90 to 95% homology and 32.degree. C. for 85 to 90% homology. In a clinical diagnostic embodiment, the nucleic acid sequences of the TfR genes of the present invention may be used in combination with an appropriate means, such as a label, for determining hybridization. A wide variety of appropriate indicator means are known in the art, including radioactive, enzymatic or other ligands, such as avidin/biotin, which are capable of providing a detectable signal. In some diagnostic embodiments, an enzyme tag such as urease, alklaine phosphatase or peroxidase, instead of a radioactive tag may be used. In the case of enzyme tags, colorimetric indicator substrates are known which can be employed to provide a means visible to the human eye or spectrophotometrically, to identify specific hybridization with samples contaiing TfR gene sequences. The nucleic acid sequences of TfR genes of the present invention are useful as hybridization probes in solution hybridizations and in embodiments employing solid-phase procedures. In embodiments involving solid-phase procedures. In embodiments involving solid-phase procedures, the test DNA (or RNA) from samples, such as clinical samples, including exudates, body fluids (e.g., serum, amniotic fluid, middle ear effusion, sputum, bronchoalveolar lavage fluid) or even tissues, is adsorbed or otherwise affixed to a selected matrix or surface. The fixed, single-stranded nucleic acid is then subjected to specific hybridization with selected probes comprising the nucleic acid sequences of the TfR genes or fragments thereof of the present invention under desired conditions. The selected conditions will depend on the particular circumstances based on the particular criteria required depending on, for example, the G+C contents, type of target nucleic acid, source of nucleic acid, size of hybridization probe etc. Following washing of the hybridization surface so as to remove non-specifically bound probe molecules, specific hybridization is detected, or even quantified, by means of the label. As with the selection of peptides, it is preferred to select nucleic acid sequence portions which are conserved among species of Haemophilus, such as nucleic acid sequences encoding the conserved peptide sequence of FIGS. 8, 9, 13 and 14 and particularly listed in Tables 2 and 3. The selected probe may be at least 18 bp and may be in the range of 30 bp to 90 bp long. 4. Expression of the Transferrin Receptor Genese Plasmid vectors containing replicon and control sequences which are derived from species compatible with the host cell may be used for the expression of the transferrin receptor genese in expression systems. The vector ordinarily carries a replication site, as well as marking sequences which are capable of providing phenotypic selection in transformed cells. For example, E. coli may be transformed using pBR2322 which contains genes for ampicillin and tetracycline resistance and thus provides easy means for identifying transformed cells. The pBR322 plasmid, or other microbial plasmid or phage must also contain, or be modified to contain, promoters which can be used by the host cell for expression of its own proteins. In addition, phase vectors containing replicon and control sequences that are compatible with the host can be used as a trnasforming vector in connection with these hosts. For example, the phage in lambda GEM.TM.-11 may be utilized in making recombinant phage vectors which can be used to transform host cells, such as E. coli LE392. Promoters commonly used in recombination DNA construction include the .beta.-lactamase (penicillinase) and lactose promoter systems (Chang et al., 1978: Itakura et al., 1977 Goeddel et al., 17979; Goeddel et al., 1980) and other microbial promoteres such as the T7 promoter system (U.S. Pat. No. 5,952,496). Details concerning the nucleotide sequences of promoters are known, enabling a skilled worker to ligate them functionally with genes. The particular promoter used will generally be a matter of choice depending upon the desired results. Hosts that are appropriate for expression of the transferrin receptor genes, fragment analogs or variants thereof include E. coli, Bacillus species, Haemophilus, fungi, yeast or the baculovirus expression system may be used. In accordance with this invention, it is preferred to make the protein by recombinant methods, particularly when the naturally occurring TfR protein as purified form a culture of a species of Haemophilus may include trace amounts of toxic materials or other contaminants. This problem can be avoided by using recombinantly produced TfR protein in heterologous systems which can be isolated from the host in a manner to minimize contaminants in the purified material. Particularly desirable hosts for expression in this regard include Gram positive bacteria which do not have LPS and are therefore endoxtoxin free. Such hosts include species of Bacillus and may be particularly useful for the production of non-pyrogenic transferrin receptor, fragments or analogs thereof. Furthermore, recombinant methods of production permit the manufacture of Tbp1 or Tbp2 or fragments thereof separate from one another which is distinct from the normal combined proteins present in Haemorphilus. Biological Deposits Certain plasmids that contain at least a portion coding for a transferrin receptor from strains of Haemophilus influenzae that are described and referred to herein have been deposited with the American Type Culture Collection (ATCC) located at Rockville, Md. USA pursuant to the Budapest Treaty and prior to the filing of this application. Samples of the deposited plasmids will become available to the public upon grant of a patent based upon this United State patent application. The invention described and claimed herein is not to be limited in scope by plasmids deposited, since the deposited embodiment is intended only as an illustration of the invention. Any equivalent or simliar plasmids that encode similar or equivalent antigens as described in this application are within the scope of the invention. Deposit Summary ______________________________________ ATCC Clone Designation Date Deposited ______________________________________ DS-712-1-3 75603 November 4, 1993 JB-1042-7-6 75607 November 4, 1993 JB-1424-2-8 75937 October 27, 1994 JB-1600-1 75935 October 27, 1994 JB-1468-29 75936 October 27, 1994 pT7TBP2A 75931 October 27, 1994 pT7TBP2B 75932 October 27, 1994 pT7TBP2C 75933 October 27, 1994 pT7TBP2D 75934 October 27, 1994 ______________________________________ Strains of Haemophilus Hib strain Eagan is available from Connaught Laboratories Limited, 1755 Steeles Ave., W., Willowdale, Ontario, Canada M2R 3T4. Hib strain MinnA was obtained from the collection of Dr. Robert Munson, Department of Microbiology and Immunology, Washington University School of Medicine, Children's Hospital, St. Louis, Miss. 63110. Hib strain DL63 was obtained from the collection of Dr. Eric Hansen, Department of Microbiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Tex. 75235-9048. PAK 12085 was obtained from the collection of Dr. Robert Munson (supra). SB12, 29, 30, 32 and 33 were obtained from the collection of Dr. Stephen Barenkamp, Department of Pediatrics, School of Medicine, Saint Louis University Medical Centre, St. Louis, Miss. 63104. |
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