| PATENT ASSIGNEE'S COUNTRY | USA |
| UPDATE | 12.99 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 07.12.99 |
| PATENT TITLE |
Recombinant poxvirus-cytomegalovirus, compositions and uses |
| PATENT ABSTRACT |
Attenuated recombinant viruses containing DNA encoding an HCMV antigen, as well as methods and compositions employing the viruses, expression products therefrom, and antibodies generated from the viruses or expression products, are disclosed and claimed. The recombinant viruses can be NYVAC or ALVAC recombinant viruses. The recombinant viruses and gene products therefrom and antibodies generated by the viruses and gene products have several preventive, therapeutic and diagnostic uses. The DNA of the recombinant viruses can be used as probes or for generating PCR primers. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 05.06.96 |
| PATENT REFERENCES CITED |
Gehrz et al, 1992, Antivival Rej., vol. 17, pp. 115-131. Tartaglia et al, 1992, Virology, vol. 188, pp. 217-232. Perkus et al, 1985, Science, vol. 229, pp. 981-984. Qadri et al, 1992, J. Gen. Virology, vol. 73, pp. 2913-2921. |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A recombinant poxvirus containing therein exogenous DNA from HCMV coding for an HCMV protein selected from the group consisting of gB, gH and combinations thereof, wherein the poxvirus is selected from the group consisting of: (i) recombinant vaccinia virus wherein regions C7L-K1L, J2R, B13R+B14R, A26L A56R and I4L have been deleted therefrom, or wherein the open reading frames for the thymidine kinase gene, the hemorrhagic region, the A type inclusion body region, the hemagglutinin gene, the host range gene region, and the large subunit, ribonucleotide reductase have been deleted therefrom; (ii) NYVAC vaccinia virus; and (iii) ALVAC canarypox virus. 2. The recombinant poxvirus of claim 1 wherein J2R, B13R+B14R, A26L, A56R, C7L-K1L and 14L are deleted from the virus. 3. The recombinant poxvirus of claim 1 wherein a thymidine kinase gene, a hemorrhagic region, an A type inclusion body region, a hemagglutinin gene, a host range region, and a large subunit, ribonucleotide reductase are deleted from the virus. 4. The recombinant poxvirus of claim 1 which is a NYVAC recombinant virus. 5. The recombinant poxvirus of claim 1 which is an ALVAC recombinant virus. 6. The recombinant poxvirus of claim 1 which is vCP233, vP1360, ALVAC-CMV6, ALVAC-CMV5, vCP236 or vCP139. 7. The recombinant poxvirus of claim 1 which is vP1173, vP1183, vP1312, vP1302B, vP1399, or vP1001. 8. A method for treating a patient in need of immunological treatment or of inducing an immunological response in an individual or animal comprising administering to said patient or individual or animal a composition comprising a virus as claimed in any one of claims 1, 2, 3, 4 or 5 in admixture with a suitable carrier. 9. A composition for inducing an immunological response comprising a virus as claimed in any one of claims 1, 2, 3, 4 or 5 in admixture with a suitable carrier. 10. A method for expressing a gene product in a cell cultured in vitro comprising introducing into the cell a virus as claimed in any one of claims 1, 2, 3, 4 or 5 in admixture with a suitable carrier. 11. The method of claim 8 further comprising administering an HCMV antigen either before or after administering the composition. 12. The method of claim 11 wherein the antigen is from the in vitro expression of a recombinant avipox virus or vaccinia virus. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION The present invention relates to a modified poxvirus and to methods of making and using the same; for instance, a vaccinia virus or avipox (e.g. canarypox or fowlpox), e.g., modified recombinant poxvirus-cytomegalovirus (CMV), e.g., human cytomegalovirus (HCMV) such as an attenuated recombinant, especially a NYVAC or ALVAC CMV or HCMV recombinant. More in particular, the invention relates to improved vectors for the insertion and expression of foreign genes for use as safe immunization vehicles to elicit an immune response against CMV or HCMV virus. Thus, the invention relates to a recombinant poxvirus, which virus expresses gene products of CMV or HCMV and to immunogenic compositions which induce an immunological response against CMV or HCMV infections when administered to a host, or in vitro (e.g., ex vivo modalities) as well as to the products of expression of the poxvirus which by themselves are useful for eliciting an immune response e.g., raising antibodies, which antibodies are useful against CMV or HCMV infection, in either seropositive or seronegative individuals, or which expression products or antibodies elicited thereby, isolated from an animal or human or cell culture as the case may be, are useful for preparing a diagnostic kit, test or assay for the detection of the virus, or of infected cells, or, of the expression of the antigens or products in other systems. The isolated expression products are especially useful in kits, tests or assays for detection of antibodies in a system, host, serum or sample, or for generation of antibodies. The poxvirus recombinants preferably contain DNA coding for any or all of CMV or HCMVgB, gH, gL, pp150, pp65 and IE1, including recombinants expressing truncated versions of IE1; and, the recombinant poxvirus DNA is useful for probes for CMV or HCMV or for preparing PCR primers for detecting the presence or absence of CMV or HCMV or antigens thereof. Several publications are referenced in this application. Full citation to these references is found at the end of the specification immediately preceding the claims or where the publication is mentioned; and each of these publications is hereby incorporated herein by reference. BACKGROUND OF THE INVENTION Vaccinia virus and more recently other poxviruses have been used for the insertion and expression of foreign genes. The basic technique of inserting foreign genes into live infectious poxvirus involves recombination between pox DNA sequences flanking a foreign genetic element in a donor plasmid and homologous sequences present in the rescuing poxvirus (Piccini et al., 1987). Specifically, the recombinant poxviruses are constructed in two steps known in the art and analogous to the methods for creating synthetic recombinants of poxviruses such as the vaccinia virus and avipox virus described in U.S. Pat. Nos. 4,769,330, 4,722,848, 4,603,112, 5,110,587, and 5,174,993, the disclosures of which are incorporated herein by reference. First, the DNA gene sequence to be inserted into the virus, particularly an open reading frame from a non-pox source, is placed into an E. coli plasmid construct into which DNA homologous to a section of DNA of the poxvirus has been inserted. Separately, the DNA gene sequence to be inserted is ligated to a promoter. The promoter-gene linkage is positioned in the plasmid construct so that the promoter-gene linkage is flanked on both ends by DNA homologous to a DNA sequence flanking a region of pox DNA containing a nonessential locus. The resulting plasmid construct is then amplified by growth within E. coli bacteria (Clewell, 1972) and isolated (Clewell et al., 1969; Maniatis et al., 1982). Second, the isolated plasmid containing the DNA gene sequence to be inserted is transfected into a cell culture, e.g. chick embryo fibroblasts, along with the poxvirus. Recombination between homologous pox DNA in the plasmid and the viral genome respectively gives a poxvirus modified by the presence, in a nonessential region of its genome, of foreign DNA sequences. The term "foreign" DNA designates exogenous DNA, particularly DNA from a non-pox source, that codes for gene products not ordinarily produced by the genome into which the exogenous DNA is placed. Genetic recombination is in general the exchange of homologous sections of DNA between two strands of DNA. In certain viruses RNA may replace DNA. Homologous sections of nucleic acid are sections of nucleic acid (DNA or RNA) which have the same sequence of nucleotide bases. Genetic recombination may take place naturally during the replication or manufacture of new viral genomes within the infected host cell. Thus, genetic recombination between viral genes may occur during the viral replication cycle that takes place in a host cell which is co-infected with two or more different viruses or other genetic constructs. A section of DNA from a first genome is used interchangeably in constructing the section of the genome of a second co-infecting virus in which the DNA is homologous with that of the first viral genome. However, recombination can also take place between sections of DNA in different genomes that are not perfectly homologous. If one such section is from a first genome homologous with a section of another genome except for the presence within the first section of, for example, a genetic marker or a gene coding for an antigenic determinant inserted into a portion of the homologous DNA, recombination can still take place and the products of that recombination are then detectable by the presence of that genetic marker or gene in the recombinant viral genome. Additional strategies have recently been reported for generating recombinant vaccinia virus. Successful expression of the inserted DNA genetic sequence by the modified infectious virus requires two conditions. First, the insertion must be into a nonessential region of the virus in order that the modified virus remain viable. The second condition for expression of inserted DNA is the presence of a promoter in the proper relationship to the inserted DNA. The promoter must be placed so that it is located upstream from the DNA sequence to be expressed. Vaccinia virus has been used successfully to immunize against smallpox, culminating in the worldwide eradication of smallpox in 1980. In the course of its history, many strains of vaccinia have arisen. These different strains demonstrate varying immunogenicity and are implicated to varying degrees with potential complications, the most serious of which are post-vaccinial encephalitis and generalized vaccinia (Behbehani, 1983). With the eradication of smallpox, a new role for vaccinia became important, that of a genetically engineered vector for the expression of foreign genes. Genes encoding a vast number of heterologous antigens have been expressed in vaccinia, often resulting in protective immunity against challenge by the corresponding pathogen (reviewed in Tartaglia et al., 1990a). The genetic background of the vaccinia vector has been shown to affect the protective efficacy of the expressed foreign immunogen. For example, expression of Epstein Barr Virus (EBV) gp340 in the Wyeth vaccine strain of vaccinia virus did not protect cottontop tamarins against EBV virus induced lymphoma, while expression of the same gene in the WR laboratory strain of vaccinia virus was protective (Morgan et al., 1988). A fine balance between the efficacy and the safety of a vaccinia virus-based recombinant vaccine candidate is extremely important. The recombinant virus must present the immunogen(s) in a manner that elicits a protective immune response in the vaccinated animal but lacks any significant pathogenic properties. Therefore attenuation of the vector strain would be a highly desirable advance over the current state of technology. A number of vaccinia genes have been identified which are non-essential for growth of the virus in tissue culture and whose deletion or inactivation reduces virulence in a variety of animal systems. The gene encoding the vaccinia virus thymidine kinase (TK) has been mapped (Hruby et al., 1982) and sequenced (Hruby et al., 1983; Weir et al., 1983). Inactivation or complete deletion of the thymidine kinase gene does not prevent growth of vaccinia virus in a wide variety of cells in tissue culture. TK.sup.- vaccinia virus is also capable of replication in vivo at the site of inoculation in a variety of hosts by a variety of routes. It has been shown for herpes simplex virus type 2 that intravaginal inoculation of guinea pigs with TK.sup.- virus resulted in significantly lower virus titers in the spinal cord than did inoculation with TK.sup.+ virus (Stanberry et al., 1985). It has been demonstrated that herpesvirus encoded TK activity in vitro was not important for virus growth in actively metabolizing cells, but was required for virus growth in quiescent cells (Jamieson et al., 1974). Attenuation of TK.sup.- vaccinia has been shown in mice inoculated by the intracerebral and intraperitoneal routes (Buller et al., 1985). Attenuation was observed both for the WR neurovirulent laboratory strain and for the Wyeth vaccine strain. In mice inoculated by the intradermal route, TK.sup.- recombinant vaccinia generated equivalent anti-vaccinia neutralizing antibodies as compared with the parental TK.sup.+ vaccinia virus, indicating that in this test system the loss of TK function does not significantly decrease immunogenicity of the vaccinia virus vector. Following intranasal inoculation of mice with TK.sup.- and TK.sup.+ recombinant vaccinia virus (WR strain), significantly less dissemination of virus to other locations, including the brain, has been found (Taylor et al., 1991a). Another enzyme involved with nucleotide metabolism is ribonucleotide reductase. Loss of virally encoded ribonucleotide reductase activity in herpes simplex virus (HSV) by deletion of the gene encoding the large subunit was shown to have no effect on viral growth and DNA synthesis in dividing cells in vitro, but severely compromised the ability of the virus to grow on serum starved cells (Goldstein et al., 1988). Using a mouse model for acute HSV infection of the eye and reactivatable latent infection in the trigeminal ganglia, reduced virulence was demonstrated for HSV deleted of the large subunit of ribonucleotide reductase, compared to the virulence exhibited by wild type HSV (Jacobson et al., 1989). Both the small (Slabaugh et al., 1988) and large (Schmidtt et al., 1988) subunits of ribonucleotide reductase have been identified in vaccinia virus. Insertional inactivation of the large subunit of ribonucleotide reductase in the WR strain of vaccinia virus leads to attenuation of the virus as measured by intracranial inoculation of mice (Child et al., 1990). The vaccinia virus hemagglutinin gene (HA) has been mapped and sequenced (Shida, 1986). The HA gene of vaccinia virus is nonessential for growth in tissue culture (Ichihashi et al., 1971). Inactivation of the HA gene of vaccinia virus results in reduced neurovirulence in rabbits inoculated by the intracranial route and smaller lesions in rabbits at the site of intradermal inoculation (Shida et al., 1988). The HA locus was used for the insertion of foreign genes in the WR strain (Shida et al., 1987), derivatives of the Lister strain (Shida et al., 1988) and the Copenhagen strain (Guo et al., 1989) of vaccinia virus. Recombinant HA.sup.- vaccinia virus expressing foreign genes have been shown to be immunogenic (Guo et al., 1989; Itamura et al., 1990; Shida et al., 1988; Shida et al., 1987) and protective against challenge by the relevant pathogen (Guo et al., 1989; Shida et al., 1987). Cowpox virus (Brighton red strain) produces red (hemorrhagic) pocks on the chorioallantoic membrane of chicken eggs. Spontaneous deletions within the cowpox genome generate mutants which produce white pocks (Pickup et al., 1984). The hemorrhagic function (u) maps to a 38 kDa protein encoded by an early gene (Pickup et al., 1986). This gene, which has homology to serine protease inhibitors, has been shown to inhibit the host inflammatory response to cowpox virus (Palumbo et al., 1989) and is an inhibitor of blood coagulation. The u gene is present in WR strain of vaccinia virus (Kotwal et al., 1989b). Mice inoculated with a WR vaccinia virus recombinant in which the u region has been inactivated by insertion of a foreign gene produce higher antibody levels to the foreign gene product compared to mice inoculated with a similar recombinant vaccinia virus in which the u gene is intact (Zhou et al., 1990). The u region is present in a defective nonfunctional form in Copenhagen strain of vaccinia virus (open reading frames B13 and B14 by the terminology reported in Goebel et al., 1990a,b). Cowpox virus is localized in infected cells in cytoplasmic A type inclusion bodies (ATI) (Kato et al., 1959). The function of ATI is thought to be the protection of cowpox virus virions during dissemination from animal to animal (Bergoin et al., 1971). The ATI region of the cowpox genome encodes a 160 kDa protein which forms the matrix of the ATI bodies (Funahashi et al., 1988; Patel et al., 1987). Vaccinia virus, though containing a homologous region in its genome, generally does not produce ATI. In WR strain of vaccinia, the ATI region of the genome is translated as a 94 kDa protein (Patel et al., 1988). In Copenhagen strain of vaccinia virus, most of the DNA sequences corresponding to the ATI region are deleted, with the remaining 3' end of the region fused with sequences upstream from the ATI region to form open reading frame (ORF) A26L (Goebel et al., 1990a,b). A variety of spontaneous (Altenburger et al., 1989; Drillien et al., 1981; Lai et al., 1989; Moss et al., 1981; Paez et al., 1985; Panicali et al., 1981) and engineered (Perkus et al., 1991; Perkus et al., 1989; Perkus et al., 1986) deletions have been reported near the left end of the vaccinia virus genome. A WR strain of vaccinia virus with a 10 kb spontaneous deletion (Moss et al., 1981; Panicali et al., 1981) was shown to be attenuated by intracranial inoculation in mice (Buller et al., 1985). This deletion was later shown to include 17 potential ORFs (Kotwal et al., 1988b). Specific genes within the deleted region include the virokine N1L and a 35 kDa protein (C3L, by the terminology reported in Goebel et al., 1990a,b). Insertional inactivation of NIL reduces virulence by intracranial inoculation for both normal and nude mice (Kotwal et al., 1989a). The 35 kDa protein is secreted like N1L into the medium of vaccinia virus infected cells. The protein contains homology to the family of complement control proteins, particularly the complement 4B binding protein (C4bp) (Kotwal et al., 1988a). Like the cellular C4bp, the vaccinia 35 kDa protein binds the fourth component of complement and inhibits the classical complement cascade (Kotwal et al., 1990). Thus the vaccinia 35 kDa protein appears to be involved in aiding the virus in evading host defense mechanisms. The left end of the vaccinia genome includes two genes which have been identified as host range genes, K1L (Gillard et al., 1986) and C7L (Perkus et al., 1990). Deletion of both of these genes reduces the ability of vaccinia virus to grow on a variety of human cell lines (Perkus et al., 1990). Two additional vaccine vector systems involve the use of naturally host-restricted poxviruses, avipox viruses. Both fowlpoxvirus (FPV) and canarypoxvirus (CPV) have been engineered to express foreign gene products. Fowlpox virus (FPV) is the prototypic virus of the Avipox genus of the Poxvirus family. The virus causes an economically important disease of poultry which has been well controlled since the 1920's by the use of live attenuated vaccines. Replication of the avipox viruses is limited to avian species (Matthews, 1982) and there are no reports in the literature of avipoxvirus causing a productive infection in any non-avian species including man. This host restriction provides an inherent safety barrier to transmission of the virus to other species and makes use of avipoxvirus based vaccine vectors in veterinary and human applications an attractive proposition. FPV has been used advantageously as a vector expressing antigens from poultry pathogens. The hemagglutinin protein of a virulent avian influenza virus was expressed in an FPV recombinant (Taylor et al., 1988a). After inoculation of the recombinant into chickens and turkeys, an immune response was induced which was protective against either a homologous or a heterologous virulent influenza virus challenge (Taylor et al., 1988a). FPV recombinants expressing the surface glycoproteins of Newcastle Disease Virus have also been developed (Taylor et al., 1990; Edbauer et al., 1990). Despite the host-restriction for replication of FPV and CPV to avian systems, recombinants derived from these viruses were found to express extrinsic proteins in cells of nonavian origin. Further, such recombinant viruses were shown to elicit immunological responses directed towards the foreign gene product and where appropriate were shown to afford protection from challenge against the corresponding pathogen (Tartaglia et al., 1993a,b; Taylor et al., 1992; 1991b; 1988b). Human cytomegalovirus (HCMV) is a member of the betaherpesviridae subfamily (family Herpesviridae). HCMV is ubiquitous in humans, with usually mild or inapparent acute infection followed by persistence or latency. However, HCMV is a significant cause of morbidity and mortality in infants infected in-utero (Stagno et al., 1983). HCMV is the most common infectious complication of organ transplantation (Glenn et al., 1981) and in immunocompromised hosts (Weller et al., 1971). In AIDS patients, CMV retinitis is the leading cause of blindness (Roarty et al., 1993; Gallant et al., 1992; Gross et al., 1990) A potential role of HCMV in coronary restinosis has recently been described (Speir et al., 1994). The live attenuated Towne strain of HCMV has been shown to protect seronegative renal transplant recipients from severe clinical symptoms of HCMV infection (Plotkin et al., 1976, 1984 and 1989) and to protect initially seronegative healthy individuals from infection and clinical symptoms after subcutaneous challenge with a wild-type strain of HCMV (Plotkin et al., 1989). Concerns remain about the use of a live HCMV vaccine because of the latency reactivation phenomenon characteristic of herpesvirus infections in humans and because of the capability of certain strains of HCMV to transform cells malignantly in vitro (Albrecht and Rapp, 1973; Galloway et al., 1986). For these reasons, a recombinant subunit CMV vaccine may be more acceptable for human immunization. The role of individual HCMV proteins in protective immunity is unclear. Three immunologically distinct families of glycoproteins associated with the HCMV envelope have been described (Gretch et al., 1988b); gCI (gp55 and gp93-130); gCII (gp47-52); and gCIII (gp85-p145). Neutralization of HCMV has been demonstrated in vitro with antibodies specific for each of these glycoprotein families (Pachl et al., 1989; Rasmussen et al., 1988; Kari et al., 1986). The gene coding for gCI is homologous to HSV I gB (Cranage et al., 1986). HCMVgB is synthesized as a glycosylated uncleaved precursor of apparent molecular weight 130-140 kDa which is processed by cellular proteinase into N-terminal 90-110 kDa and C-terminal 55-58 kDa products which remain associated in a disulfide linked complex (Britt and Auger, 1986; Britt and Vugler, 1989; Reis et al., 1993). Monoclonal antibodies capable of neutralizing HCMV have been obtained from mice immunized with lysates of HCMV infected cells or HCMV virions, these monoclonals were predominantly reactive with the C-terminal 55-58 kDa fragment (Britt, 1984; Kari et al., 1986; Pereira et al., 1984; Rasmussen et al., 1988). However, immunization with biochemically purified gP93 resulted in the development of gp93-specific neutralizing mAbs (Kari et al., 1990). HCMV-gB may serve to elicit protective immunity in humans: immunization with the purified gB protein induces neutralizing antibody (Gonczol et al., 1990) and human antigB monoclonal antibodies neutralize the virus (Masuho et al., 1987). Following natural infection neutralizing antibody specific for HCMV-gB is observed. When gB specific antibody is absorbed from human sera, HCMV neutralizing antibody titer is reduced significantly (50-88%, Gonczol et al., 1991; 0-98% median 48%, Marshall et al., 1992). There is also evidence for activation of helper T cells by the gB protein in naturally seropositive humans (Liu et al., 1991) and gB specific CTL has been detected in humans in some studies (Borysiewicz et al., 1988; Liu et al., 1991; Riddell, et al., 1991). The gCII glycoproteins are encoded by a gene or genes in the US6 gene family (US6 through US11, Gretch et al., 1988a). These glycoproteins are recognized by human anti-HCMV antibody in sera from convalescent adults. However, sera from congenitally infected infants with persistent infection failed to react with gCII glycoproteins (Kari and Gehrz, 1990), suggesting that gCII may be important to human protective immune responses to HCMV. The gP86 component of the gCIII complex is encoded by a gene that is homologous to HSV-I gH (Cranage et al., 1988; Pachl et al., 1989). The HCMV gH protein is capable of inducing a neutralizing immune response in humans (10% of HCMV infected individuals have a detectable level of circulating gH specific antibody (Rasmussen et al., 1991) as well as in laboratory animals (Baboonian et al., 1989; Cranage et al., 1988; Ehrlich et al., 1988; Rasmussen et al., 1984). Murine gH-specific monoclonal antibodies neutralize virus infectivity in a complement-independent manner (Baboonian et al., 1989; Cranage et al., 1988; Rasmussen et al., 1984) and inhibit viral spread (Pachl et al., 1989) suggesting that gH may be responsible for virus attachment, penetration and or spread. Although gH is found on the surface of HCMV infected cells (Cranage et al., 1988), when expressed by a variety of recombinant systems it is restricted to the endoplasmic reticulum (Spaete et al., 1991). Coexpression of the HCMV UL115 gene product (glycoprotein gL) results in the formation of a stable complex of these two proteins and the transport of gH to the cell surface (Spaete et al., 1993; Kaye et al., 1992). HCMV synthesizes a number of matrix tegument phosphoproteins. The pp150 phosphoprotein is highly immunogenic apparently more so than any other of the HCMV structural proteins (Jahn et al., 1987). A second matrix phosphoprotein, pp65, elicits a variable humoral response in humans (Jahn et al., 1987; Plachter et al., 1990). This protein can stimulate lymphoproliferation, IL-2 and interferon production, B-cell stimulation of antibody and natural killer cell activity (Forman et al., 1985). It also serves as a target antigen for HCMV-specific, HLA-restricted cytotoxic T cells (CTLs) (Pande et al., 1991; Gilbert et al., 1993). Additional structural proteins may be required for eliciting a protective immune response to HCMV. The major capsid protein (UL86) is known to induce specific antibodies during natural infection and has been considered as the CMV-group common antigen (Spaete et al., 1994). The tegument phosphoprotein, pp28 (UL99), is also known to elicit persistent antibody responses during a natural infection. Further, this protein has also been implicated as a CTL target immunogen (Charpentier et al., 1986). The immune response to the upper tegument phosphoprotein, pp71 (UL82), is not as well characterized as the other tegument phosphoproteins (pp28, pp65), but as a known tegument protein requires further attention. In addition to these structural proteins, some nonstructural proteins may also be candidates for inclusion in a recombinant subunit vaccine. Immunization of mice with a recombinant vaccinia virus expressing murine cytomegalovirus (MCMV) pp89 (functional homolog of HCMV IE 1) induces CD8.sup.+ T-cell responses that mediate protective immunity from challenge with MCMV (Jonjic et al., 1988). The human CMV major immediate early protein (IE 1) has been shown to be a target for CTLs isolated from HCMV seropositive individuals (Borysiewicz et al., 1988). Since IE 1 is among the initial viral proteins expressed and is necessary for inducing the expression of other CMV genes and initiating the viral life cycle in latently infected cells (Blanton and Tevethia, 1981; Cameron and Preston, 1981; DeMarchi et al., 1980: McDonough and Spector, 1983; Wathen et al., 1981), CTL responses directed against IE 1 may be important for controlling and/or eliminating HCMV infection. Recently Gilbert et al., (1993) have suggested that HCMV has evolved a mechanism by which other viral encoded proteins selectively interfere with the presentation of IE-derived peptides in association with Class I major histocompatibility complex (MHC) molecules. Some additional nonstructural proteins may also be candidates for inclusion in a recombinant subunit HCMV vaccine candidate. The immediate early protein, IE2 (UL122), and the regulatory protein UL69 are known to contain human T-helper epitopes (Beninga et al., 1995). One approach to the development of a subunit HCMV vaccine is the use of live viral vectors to express relevant HCMV gene products. It can thus be appreciated that provision of a CMV or an HCMV recombinant poxvirus, and of compositions and products therefrom particularly NYVAC or ALVAC based CMV or HCMV recombinants and compositions and products therefrom, especially such recombinants containing coding for any or all of HCMVgB, gH, gL, pp150, pp65 and IE1, including recombinants expressing altered or truncated versions of IE1 and/or gB and compositions and products therefrom would be a highly desirable advance over the current state of technology. OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of this invention to provide modified recombinant viruses, which viruses have enhanced safety, and to provide a method of making such recombinant viruses. It is an additional object of this invention to provide a recombinant poxvirus antigenic vaccine or immunological composition having an increased level of safety compared to known recombinant poxvirus vaccines. It is a further object of this invention to provide a modified vector for expressing a gene product in a host, wherein the vector is modified so that it has attenuated virulence in the host. It is another object of this invention to provide a method for expressing a gene product in a cell cultured in vitro using a modified recombinant virus or modified vector having an increased level of safety. These and other objects and advantages of the present invention will become more readily apparent after consideration of the following. In one aspect, the present invention relates to a modified recombinant virus having inactivated virus-encoded genetic functions so that the recombinant virus has attenuated virulence and enhanced safety. The functions can be non-essential, or associated with virulence. The virus is advantageously a poxvirus, particularly a vaccinia virus or an avipox virus, such as fowlpox virus or canarypox virus. The modified recombinant virus can include, within a non-essential region of the virus genome, a heterologous DNA sequence which encodes an antigen or epitope derived from HCMV, such as any or all of HCMVgB, gH, gL, pp150, pp65, IE1, including altered or truncated versions of IE1, and/or gB. In another aspect, the present invention relates to an antigenic, immunological or vaccine composition or a therapeutic composition for inducing an antigenic or immunological response in a host animal inoculated with the composition, said vaccine including a carrier and a modified recombinant virus having inactivated nonessential virus-encoded genetic functions so that the recombinant virus has attenuated virulence and enhanced safety. The virus used in the composition according to the present invention is advantageously a poxvirus, particularly a vaccinia virus or an avipox virus, such as fowlpox virus and canarypox virus. The modified recombinant virus can include, within a nonessential region of the virus genome, a heterologous DNA sequence which encodes an antigenic protein, e.g., derived from HCMV, such as any or all of HCMVgB, gH, gL, pp150, pp65, IE1, including altered or truncated versions of IE1, and/or gB. In yet another aspect, the present invention relates to an immunogenic composition containing a modified recombinant virus having inactivated nonessential virus-encoded genetic functions so that the recombinant virus has attenuated virulence and enhanced safety. The modified recombinant virus includes, within a non-essential region of the virus genome, a heterologous DNA sequence which encodes an antigenic protein (e.g., derived from HCMV, such as any or all of HCMVgB, gH, gL, pp150, pp65, IE1, including altered or truncated versions of IE1, and/or gB) wherein the composition, when administered to a host, is capable of inducing an immunological response specific to the antigen. In a further aspect, the present invention relates to a method for expressing a gene product in a cell in vitro by introducing into the cell a modified recombinant virus having attenuated virulence and enhanced safety. The modified recombinant virus can include, within a nonessential region of the virus genome, a heterologous DNA sequence which encodes an antigenic protein, e.g. derived from HCMV such as any or all of HCMVgB, gH, gL, pp150, pp65, IE1, including altered or truncated versions of IE1, and/or gB. The cells can then be reinfused directly into the individual or used to amplify specific reactivities for reinfusion (Ex vivo therapy). In a further aspect, the present invention relates to a method for expressing a gene product in a cell cultured in vitro by introducing into the cell a modified recombinant virus having attenuated virulence and enhanced safety. The modified recombinant virus can include, within a nonessential region of the virus genome, a heterologous DNA sequence which encodes an antigenic protein, e.g., derived from HCMV such as any or all of HCMVgB, gH, gL, pp150, pp65, IE1, including altered or truncated versions of IE1, and/or gB. The product can then be administered to individuals or animals to stimulate an immune response. The antibodies raised can be useful in individuals for the prevention or treatment of HCMV and, the antibodies from individuals or animals or the isolated in vitro expression products can be used in diagnostic kits, assays or tests to determine the presence or absence in a sample such as sera of HCMV or antigens therefrom or antibodies thereto (and therefore the absence or presence of the virus or of the products, or of an immune response to the virus or antigens). In a still further aspect, the present invention relates to a modified recombinant virus having nonessential virus-encoded genetic functions inactivated therein so that the virus has attenuated virulence, and wherein the modified recombinant virus further contains DNA from a heterologous source in a nonessential region of the virus genome. The DNA can code for HCMV such as any or all of HCMVgB, gH, gL, pp150, pp65, IE1, including altered or truncated versions of IE1, and/or gB. In particular, the genetic functions are inactivated by deleting an open reading frame encoding a virulence factor or by utilizing naturally host restricted viruses. The virus used according to the present invention is advantageously a poxvirus, particularly a vaccinia virus or an avipox virus, such as fowlpox virus or canarypox virus. Advantageously, the open reading frame is selected from the group consisting of J2R, B13R+B14R, A26L, A56R, C7L-K1L, and I4L (by the terminology reported in Goebel et al., 1990a,b); and, the combination thereof. In this respect, the open reading frame comprises a thymidine kinase gene, a hemorrhagic region, an A type inclusion body region, a hemagglutinin gene, a host range gene region or a large subunit, ribonucleotide reductase; or, the combination thereof. A suitable modified Copenhagen strain of vaccinia virus is identified as NYVAC (Tartaglia et al., 1992), or a vaccinia virus from which has been deleted J2R, B13R+B14R, A26L, A56R, C7L-K1l and I4L or a thymidine kinase gene, a hemorrhagic region, an A type inclusion body region, a hemagglutinin gene, a host range region, and a large subunit, ribonucleotide reductase (See also U.S. Pat. No. 5,364,773). Alternatively, a suitable poxvirus is an ALVAC or, a canarypox virus (Rentschler vaccine strain) which was attenuated, for instance, through more than 200 serial passages on chick embryo fibroblasts, a master seed therefrom was subjected to four successive plaque purifications under agar from which a plaque clone was amplified through five additional passages. The invention in yet a further aspect relates to the product of expression of the inventive recombinant poxvirus and uses therefor, such as to form antigenic, immunological or vaccine compositions for treatment, prevention, diagnosis or testing; and, to DNA from the recombinant poxvirus which is useful in constructing DNA probes and PCR primers. These and other embodiments are disclosed or are obvious from and encompassed by the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS The following detailed description, given by way of example, but not intended to limit the invention solely to the specific embodiments described, may best be understood in conjunction with the accompanying drawings, in which: FIG. 1 schematically shows a method for the construction of plasmid pSD460 for deletion of thymidine kinase gene and generation of recombinant vaccinia virus vP410; FIG. 2 schematically shows a method for the construction of plasmid pSD486 for deletion of hemorrhagic region and generation of recombinant vaccinia virus vP553; FIG. 3 schematically shows a method for the construction of plasmid pMP494.DELTA. for deletion of ATI region and generation of recombinant vaccinia virus vP618; FIG. 4 schematically shows a method for the construction of plasmid pSD467 for deletion of hemagglutinin gene and generation of recombinant vaccinia virus vP723; FIG. 5 schematically shows a method for the construction of plasmid pMPCK1.DELTA. for deletion of gene cluster [C7L-K1L] and generation of recombinant vaccinia virus vP804; FIG. 6 schematically shows a method for the construction of plasmid pSD548 for deletion of large subunit, ribonucleotide reductase and generation of recombinant vaccinia virus vP866 (NYVAC); FIG. 7 schematically shows a method for the construction of plasmid pRW842 for insertion of rabies glycoprotein G gene into the TK deletion locus and generation of recombinant vaccinia virus vP879; FIG. 8 shows the DNA sequence of a 3209 base pair fragment of canarypox DNA containing the C5 ORF (SEQ ID NO:27) (the C5 ORF initiates at position 1537 and terminates at position 1857); FIGS. 9A and 9B schematically show a method for the construction of recombinant canarypox virus vCP65 (ALVACRG); FIG. 10 shows schematically the ORFs deleted to generate NYVAC; FIGS. 11A to 11D show graphs of rabies neutralizing antibody titers (RFFIT, IU/ml), booster effect of HDC and vCP65 (10.sup.5.5 TCID.sub.50) in volunteers previously immunized with either the same or the alternate vaccine (vaccines given at days 0, 28 and 180, antibody titers measured at days 0, 7, 28, 35, 56, 173, 187 and 208); FIG. 12 shows the DNA sequence of HCMVgB (Towne strain) (SEQ ID NO:37); FIGS. 13A and B show the DNA sequence of the H6 promoted HCMVgB and NYVAC sequences flanking the TK locus (SEQ ID NO:38) (the 5'end of the H6 promoted CMVgB is at position 3447; the CMVgB coding sequence is from position 3324 through position 606); FIGS. 14A to C show the DNA sequence of a 7351 base pair fragment of canarypox DNA containing the C3 ORF (SEQ ID NO:39) (the C3 ORF is initiated at position 1458 and terminates at position 2897); FIGS. 15A to C show the DNA sequence of the H6 promoted HCMVgB and ALVAC sequences flanking the C3 locus (SEQ ID NO:40) (the 5' end of the H6 promoted CMVgB is at position 4425; the CMVgB coding sequence is from position 4301 through position 1581); FIGS. 16A and B show the DNA sequence of the H6 promoted HCMVgB and NYVAC sequences flanking the ATI locus (SEQ ID NO:41) (the 5'end of the H6 promoted CMVgB is at position 3348; the CMVgB coding sequence is from position 3224 through position 504); FIG. 17 shows the DNA sequence of HCMVgB (Towne strain) deleted of its transmembrane region (SEQ ID NO:42); FIGS. 18A and B show the DNA sequence of the H6 promoted HCMVgB lacking its transmembrane region and NYVAC sequences flanking the ATI locus (SEQ ID NO:43) (the 5' end of the H6 promoted CMVgB is at position 3173; the CMVgB coding sequence is from position 3050 through position 504); FIG. 19 shows the DNA sequence of HCMVgB (Towne strain) deleted of its transmembrane region and containing an altered cleavage site (SEQ ID NO:44); FIGS. 20A and B show the DNA sequence of the H6 promoted HCMVgB lacking its transmembrane region and containing an altered cleavage site plus NYVAC sequences flanking the ATI locus (SEQ ID NO:45) (the 5' end of the H6 promoted CMVgB is at position 3173; the CMVgB coding sequence is from position 3050 through position 504); FIG. 21 shows the DNA sequence of HCMVgH (Towne strain) (SEQ ID NO:46); FIGS. 22A and B show the DNA sequence of the 42K promoted HCMVgH plus NYVAC sequences flanking the I4L locus (SEQ ID NO:47) (the 5' end of the 42K promoted CMVgH is at position 641; the CMVgH coding sequence is from position 708 through position 2933); FIGS. 23A and B show the DNA sequence of the 42K promoted CMVgH and ALVAC sequences flanking the C5 locus (SEQ ID NO:48) (the 5' end of the 42K promoted CMVgH is at position 1664; the CMVgH coding sequence is from position 1730 through position 3955); FIG. 24 shows the DNA sequence of the 42K promoted CMVgH and WR flanking sequences (SEQ ID NO:49) (the 5' end of the 42K promoted CMVgH is at position 2457; the CMVgH coding sequence is from position 2391 through 166); FIG. 25 shows the DNA sequence of HCMV IE1 (AD169 strain) (SEQ ID NO:50); FIG. 26 shows the DNA sequence of the H6 promoted CMVIE1 and WR flanking sequences (SEQ ID NO:51) (the 5' end of the H6 promoted CMVIE1 is at position 1796; the CMVIE1 coding sequence is from position 1673 through 201); FIGS. 27A and B show the DNA sequence of the H6 promoted CMVIE1 and NYVAC sequences flanking the ATI locus (SEQ ID NO:52) (the 5' end of the H6 promoted CMVIE1 is at position 2030; the CMVIE1 coding sequence is from position 1906 through position 434); FIG. 28 shows the DNA sequence of HCMVIE1 (AD169 strain) lacking amino acids 292-319 (SEQ ID NO:53); FIGS. 29A and B show the DNA sequence of the H6 promoted CMVIE1 lacking amino acids 292-319 and NYVAC sequences flanking the ATI locus (SEQ ID NO:54) (the 5' end of the H6 promoted CMVIE1 is at position 1940; the CMVIE1 coding sequence is from position 1816 through position 434); FIG. 30 shows the DNA sequence of the Exon 4 segment of HCMVIE1 (AD169 strain) (SEQ ID NO:55); FIG. 31 shows the DNA sequence of the H6 promoted CMVIE1 Exon 4 segment and NYVAC sequences flanking the I4L locus (SEQ ID NO:56) (the 5' end of the H6 promoted IE1 Exon 4 is at position 630; the CMVIE1 Exon 4 coding sequence is from position 754 through position 1971). FIG. 32A and B show the DNA sequence of the H6 promoted CMVIE1 Exon 4 segment and ALVAC sequences flanking the C5 locus (SEQ ID NO:57) (the 5' end of the H6 promoted IE1 Exon 4 is at position 1647; the CMVIE1 Exon 4 coding sequence is from position 1771 through position 2988). FIG. 33 shows the DNA sequence of HCMVIE1 (AD169 strain) lacking amino acids 2-32 (SEQ ID NO:58); FIG. 34 shows the DNA sequence of the H6 promoted CMVIE1 lacking amino acids 2-32 and NYVAC sequences flanking the I4L locus (SEQ ID NO:59) (the 5' end of the H6 promoted IE1 lacking amino acids 2-32 is at position 630; the coding sequence for CMVIE1 lacking amino acids 2-32 is from position 754 through position 2133); FIGS. 35A and B show the DNA sequence of the H6 promoted CMVIE1 lacking amino acids 2-32 and ALVAC sequences flanking the C5 locus (SEQ ID NO:60) (the 5' end of the H6 promoted IE1 lacking amino acids 2-32 is at position 1647; the CMVIE1 coding sequence for CMVIE1 lacking amino acids 2-32 is from position 1771 through position 3150); FIG. 36 shows the DNA sequence of HCMV pp65 (Towne strain) (SEQ ID NO:61); FIG. 37 shows the DNA sequence of the H6 promoted CMVpp65 and NYVAC sequences flanking the HA locus (SEQ ID NO:62) (the 5' end of the H6 promoted pp65 is at position 476; the CMVpp65 coding sequence is from position 600 through 2282); FIGS. 38A and B show the DNA sequence of a 3706 base pair fragment of canarypox DNA containing the C6 ORF (SEQ ID NO:63) (the C6 ORF is initiated at position 377 and terminated at position 2254); FIGS. 39A and B show the DNA sequence of the H6 promoted CMVpp65 and ALVAC sequences flanking the C6 locus (SEQ ID NO:64) (the 5' end of the H6 promoted pp65 is at position 496; the CMVpp65 coding sequence is from position 620 through 2302); FIG. 40 shows the DNA sequence of the H6 promoted CMVpp65 and WR flanking sequences (SEQ ID NO:65) (the 5' end of the H6 promoted pp65 is at position 168; the CMVpp65 coding sequence is from position 292 through 1974); FIG. 41 shows the DNA sequence of HCMVpp150 (Towne strain) (SEQ ID NO:66); FIGS. 42A and B show the DNA sequence of the 42K promoted CMVpp150 and NYVAC sequences flanking the ATI locus (SEQ ID NO:67) (the 5' end of the 42K promoted pp150 is at position 3645; the CMVpp150 coding sequence is from position 3580 through 443); FIGS. 43A and B show the DNA sequence of the 42K promoted CMVpp150 and ALVAC sequences flanking the C6 locus (SEQ ID NO:68) (the 5' end of the 42K promoted pp150 is at position 3714; the CMVpp150 coding sequence is from position 3649 through 512); FIGS. 44A and B show the DNA sequence of the 42K promoted CMVpp150 gene and WR flanking sequences (SEQ ID NO:69) (the 5' end of the H6 promoted pp150 is at position 3377; the CMVpp150 coding sequence is from position 3312 through 175); FIGS. 45A and B show the DNA sequence of the 42K promoted HCMVgH and H6 promoted HCMVIE Exon 4 and NYVAC sequences flanking the I4L locus (SEQ ID NO:70) (the 5' end of the 42K promoted CMVgH is at position 2935; the CMVgH coding sequence is from position 2869 through 644; the 5' end of the H6 promoted CMVIE Exon 4 is at position 2946; the CMVIE Exon 4 coding sequence is from position 3070 through position 4287); FIGS. 46A to C show the DNA sequence of the H6 promoted HCMV pp65 and 42K promoted HCMVpp150 and ALVAC sequences flanking the C6 locus (SEQ ID NO:71) (the 5' end of the H6 promoted CMVpp65 is at position 496; the CMVpp65 coding sequence is from position 620 through 2302; the 5' end of the 42K promoted CMVpp150 is at position 5554; the CMVpp150 coding sequence is from position 5489 through position 2352); FIG. 47 shows the DNA sequence of HCMVgL (Towne strain) (SEQ ID NO:72); FIGS. 48A and B show the DNA sequence of the H6 promoted HCMVgB and H6 promoted HCMVgL and NYVAC sequences flanking the TK locus (SEQ ID NO:73) (the 5' end of the H6 promoted CMVgB is at position 3447; the CMVgB coding sequence is from position 3324 through position 606; the 5' end of the H6 promoted CMVgL is at position 3500; the CMVgL coding sequence is from position 3624 through position 4460); FIG. 49 shows the results of HCMV IE1 CTL stimulation by ALVAC-IE1 (vCP256) (percent cytotoxicity; white bars=WR, black bars=WRIE1, striped bars=nonautologous); FIG. 50 shows the results of stimulation of HCMV pp65-CTLs by ALVAC-pp65 (vCP260) (human CTLs stimulated in vitro and assayed for HCMV pp65 CTLs using methodology similar to that used for FIG. 49; percent cytotoxity; white bars=WR, black bars=WR-pp65, striped bars=nonautologous); FIG. 51 shows the results of stimulation of HCMV IE1 CTLs by ALVAC-IE1 (vCP256) (methodology similar to that used for FIG. 49, except that following 6 days incubation for restimulation, the responder mononuclear cells were incubated with immunomagnetic beads coupled to monoclonal anti-human CD3, CD4 or CD8; percent cytotoxicity; white bars=WR, black bars=WR-IE1, striped bars=HLA mismatch); FIGS. 52A to D show expression of CMV gB by COPAK recombinants in Vero and HeLa cells (cell and medium fractions from infected cells radiolabeled with [S 35] methionine were immune precipitated with guinea pig anti-CMV gB; Vero medium (A), HeLa medium (B), Vero cell (C), and HeLa cell (D) fractions derived from infections by vP993 COPAK parent (lanes 1), vP1126 expressing the entire gB (lanes 2), vP1128 expressing gB without the transmembrane site (lanes 3), and vP1145 expressing the gB without transmembrane and with altered cleavage sites (lanes 4) are shown; far right lane contains molecular weight markers); FIGS. 53A and B show vaccinia infection of Vero and HeLa cells detected by expression of vaccinia early protein E3L (cell fractions from infected cells radiolabeled with [35 S] methionine were immune precipitated with rabbit anti-p25 (E3L); Vero (A) and HeLa (B) cell fractions derived from infections by vP993 (lanes 1), vP1126 (lanes 2), vP1128 (lanes 3), and vP1145 (lanes 4) are shown; far right lane contains molecular weight markers); FIG. 54 shows comparison of CMV gB production by Vero, HeLa and MRC-5 cells (SDS-PAGE and western blot analysis were performed on the medium from MRC-5 cells (lanes 1, 4), Vero cells (lanes 2, 5), or HeLa cells (lanes 3, 6) after infection with vP1145 (lanes 1, 2, 3) or vP993 (lanes 4, 5, 6); CMV gB was detected with monoclonal CH380; molecular weight markers are present in lane M); FIG. 55 shows immunoprecipitation of CMV gB by a panel of monoclonal antibodies and guinea pig anti-gB (radiolabeled medium fractions from Vero cells infected with vP993 (lanes 1), vP1126 (lanes 2), vP1128 (lanes 3), and vP1145 (lanes 4) were immune precipitated with guinea pig anti-CMV gB or with monoclonals 13-127, 13-128, CH380, HCMV 34, or HCMV 37; far left lane contains molecular weight markers); FIG. 56 shows western blot analysis of fractions and bed material from CMV gB immunoaffinity chromatography columns (column 19 fractions representing eluted gB (lane 5), flow through material (lane 6), and crude gB material applied to the column (lane 7) were analyzed by SDS-PAGE and western blot using monoclonal CH380; included in the assay was bed material from column 19 (lane 2) and column 11 (lane 3), as well as gB purified on column 7 (lane 4); molecular weight markers are present in lane 1); FIG. 57 shows SDS-PAGE analysis of CMV gB eluted from an immunoaffinity chromatography column (fractions 8.16 through 8.22, eluted from column 8, were electrophoretically separated on a 10% gel under reducing conditions, and stained with silver); FIG. 58 shows SDS-PAGE analysis of five batches of immunoaffinity purified CMV gB (samples of batches 1 through 5 (lanes 1-5) were electrophoretically separated on a 10% gel under reducing conditions and stained with Coomassie Blue; Lane M contains molecular weight markers); FIGS. 59, 59A shows characterization of immunoaffinity purified CMV gB (batch 5, analyzed by SDS-PAGE, as shown in FIGS. 58A and B, was scanned with a densitometer, and bands were defined (lane 7, labels 1 through 8) with FIG. 59A showing a densitometer tracing through lane 7); FIGS. 60A and B show immunoblot analysis of immunoaffinity purified CMV gB (purified HIV env (lanes 1), affinity purified CMV gB (lanes 2), crude CMV gB (lane (B3), or monoclonal CH380 (lane A3) were electrophoretically separated on a 10% gel, blotted onto nitrocellulose paper and probed for the presence of mouse IgG H and L chains or CMVgB using goat anti-mouse IgG (A) or monoclonal CH380 (B), respectively; molecular weight markers are present in lanes 4); FIGS. 61A and B show immunoprecipitation/immunoblot analysis of affinity purified gB (Batch 1 immunoaffinity purified gB(1) or crude gB (B) was immunoprecipitated with monoclonals CH380 (lanes 1), 13-127 (lanes 2), 13-128 (lanes 3), HCMV 37 (lanes 4), or HCMV 34 (lanes 5); the immunoprecipitates were electrophoretically separated on a 10% gel under reducing conditions, blotted onto nitrocellulose and probed for the presence of gB, using guinea pig anti-CMB gB; far left lanes are molecular weight markers); FIGS. 62A and B show immunoblot analysis of affinity purified CMV gB (Vero cells lysates (lanes A3, B2), CEF lysates (lane A2), vaccinia-infected Vero cells (lane B3), crude CMV gB (lanes 4), affinity purified CMV gB (lanes 5), or purified HIV env (lanes 6) were electrophoretically separated on a 10% gel under reducing conditions, blotted onto nitrocellulose, and probed for the presence of Vero cell proteins using rabbit anti-Vero cells (A), or vaccinia proteins using rabbit anti-vaccinia (B); molecular weight markers are present in lanes 1); FIGS. 63A-C show the DNA sequence of the H6 promoted HCMVpp65 and 42K promoted HCMVpp150 and ALVAC sequences flanking the C6 locus (SEQ ID NO: 188) (The 5' end of the H6 promoted CMVpp65 is at position 496. The CMVpp65 coding sequence is from position 620 through 2302. The 5' end of the 42K promoted CMVpp150 is at position 2341. The CMVpp150 coding sequence is from position 2406 through 5543);. FIGS. 64A and B show the DNA sequence of a 5798bp fragment of canarypox DNA containing the C.sub.7 ORF (tk) (SEQ ID NO: 189) (The C.sub.7 ORF is initiated at position 4412 and terminated at position 4951); FIG. 65A and B show the DNA sequence of the H6 promoted HCMVgL gene and ALVAC sequences flanking the C.sub.7 locus (The 5' end of the H6 promoted CMVgL gene is at position 2136. The CMVgL coding sequence is from position 2260 through 3093); FIGS. 66A and B show the DNA sequence of the H6 promoted HCMVgL gene and H6 promoted HCMV IE1-exon4 gene and ALVAC sequences flanking the C.sub.7 locus (SEQ ID NO: 190) (The 5' end of the H6 promoted CMVgL gene is at position 3476. The CMVgL coding region is from position 3600 through 4433. The 5' end of the H6 promoted IE1-exon4 is at position 3469. The CMV IE1-exon4 coding region is from position 3345 through 2128); FIG. 67 shows the DNA sequence of HCMVgH (SEQ ID NO: 191)(Towne strain) deleted of its transmembrane region and cytoplasmic tail; and FIGS. 68A and B show the DNA sequence of the H6 promoted HCMVgL gene and 42K promoted truncated HCMVgH gene and NYVAC sequences flanking the ATI locus (SEQ ID NO: 191) (The 5' end of the H6 promoted CMVgL gene is at position 2669. The CMVgL coding region is from position 2793 through 3626. The 5' end of the 42K promoted truncated CMVgH gene is at position 2650. The truncated CMVgH coding sequence is from position 2584 through 434). DETAILED DESCRIPTION OF THE INVENTION To develop a new vaccinia vaccine strain, NYVAC (vP866), the Copenhagen vaccine strain of vaccinia virus was modified by the deletion of six nonessential regions of the genome encoding known or potential virulence factors. The sequential deletions are detailed below (See U.S. Pat. No. 5,364,773). All designations of vaccinia restriction fragments, open reading frames and nucleotide positions are based on the terminology reported in Goebel et al., 1990a,b. The deletion loci were also engineered as recipient loci for the insertion of foreign genes. The regions deleted in NYVAC are listed below. Also listed are the abbreviations and open reading frame designations for the deleted regions (Goebel et al., 1990a,b) and the designation of the vaccinia recombinant (vP) containing all deletions through the deletion specified: (1) thymidine kinase gene (TK; J2R) vP410; (2) hemorrhagic region (u; B13R+B14R) vP553; (3) A type inclusion body region (ATI; A26L) vP618; (4) hemagglutinin gene (HA; A56R) vP723; (5) host range gene region (C7L-K1L) vP804; and (6) large subunit, ribonucleotide reductase (I4L) vP866 (NYVAC). NYVAC is a genetically engineered vaccinia virus strain that was generated by the specific deletion of eighteen open reading frames encoding gene products some of which associated with virulence and host range (Tartaglia et al., 1992; Goebel et al., 1990a,b). The deletion of host range genes diminishes the ability of the virus to replicate in tissue culture cell derived from certain species such as swine and humans (Tartaglia et al., 1992; Perkus et al., 1990). In addition to reduced replication competency, NYVAC was shown to be highly attenuated by a number of criteria including (a) lack of induration or ulceration on rabbit skin, (b) rapid clearance from the site of inoculation, (c) high avirulence by intracranial inoculation into newborn mice when compared with other vaccinia strains including WYETH, and (d) failure to cause death, secondary lesions or disseminated infection when inoculated intraperitoneally in immunocompromised animals (Tartaglia et al., 1992). In spite of the highly attenuated characteristics of NYVAC, NYVAC based recombinants were effective in protecting mice from rabies challenge (Tartaglia et al., 1992), swine from challenge with Japanese encephalitis virus and pseudorabies virus challenge (Brockmeier et al., 1993; Konishi et al., 1992) and horses from equine influenza virus challenge (Taylor et al., 1993). NYVAC is also highly attenuated by a number of criteria including i) decreased virulence after intracerebral inoculation in newborn mice, ii) inocuity in genetically (nu.sup.+ /nu.sup.+) or chemically (cyclophosphamide) immunocompromised mice, iii) failure to cause disseminated infection in immunocompromised mice, iv) lack of significant induration and ulceration on rabbit skin, v) rapid clearance from the site of inoculation, and vi) greatly reduced replication competency on a number of tissue culture cell lines including those of human origin. Nevertheless, NYVAC based vectors induce excellent responses to extrinsic immunogens and provided protective immunity. Avipoxvirus-based recombinants as live vectors provide an additional approach to develop recombinant subunit vaccines. These viruses are naturally restricted by their ability to replicate only in avian species. TROVAC refers to an attenuated fowlpox that was a plaque-cloned isolate derived from the FP-1 vaccine strain of fowlpoxvirus which is licensed for vaccination of 1 day old chicks. ALVAC is an attenuated canarypox virus-based vector that was a plaque-cloned derivative of the licensed canarypox vaccine, Kanapox (Tartaglia et al., 1992). ALVAC has some general properties which are the same as some general properties of Kanapox. ALVAC-based recombinant viruses expressing extrinsic immunogens have also been demonstrated efficacious as vaccine vectors (Tartaglia et al., 1993 a,b). For instance, mice immunized with an ALVAC recombinant expressing the rabies virus glycoprotein were protected from lethal challenge with rabies virus (Tartaglia et al., 1992) demonstrating the potential for ALVAC as a vaccine vector. ALVAC-based recombinants have also proven efficacious in dogs challenged with canine distemper virus (Taylor et al., 1992) and rabies virus (Perkus et al., 1994), in cats challenged with feline leukemia virus (Tartaglia et al., 1993b), and in horses challenged with equine influenza virus (Taylor et al., 1993). This avipox vector is restricted to avian species for productive replication. On human cell cultures, canarypox virus replication is aborted early in the viral replication cycle prior to viral DNA synthesis. Nevertheless, when engineered to express extrinsic immunogens, authentic expression and processing is observed in vitro in mammalian cells and inoculation into numerous mammalian species induces antibody and cellular immune responses to the extrinsic immunogen and provides protection against challenge with the cognate pathogen (Taylor et al., 1992; Taylor et al., 1991b). Recent Phase I clinical trials in both Europe and the United States of a canarypox/rabies glycoprotein recombinant (ALVAC-RG; vCP65) demonstrated that the experimental vaccine was well tolerated and induced protective levels of rabiesvirus neutralizing antibody titers (Cadoz et al., 1992; Fries et al., 1992). Indeed, reactogenicity in volunteers following administration of ALVAC-RG was minimal; and following two administrations of ALVAC-RG at a dose of 10.sup.5.5 TCID.sub.50, all vaccinees developed rabies neutralizing antibody. Additionally, peripheral blood mononuclear cells (PBMCs) derived from the ALVAC-RG vaccinates demonstrated significant levels of lymphocyte proliferation when stimulated with purified rabies virus (Fries et al., 1992). An ALVAC recombinant expressing the HIV envelope glycoprotein gp160 (ALVAC-HIV; vCP125) has been tested in phase I human clinical trial in a prime/boost protocol with recombinant gp160 (Pialoux et al., 1995). Reactogenicity in volunteers following administration of ALVAC-HIV was minimal and this vaccine candidate primed both HIV-I envelope-specific humoral and cell-mediated immune responses. Recent studies have indicated that a prime/boost protocol, whereby immunization with a poxvirus recombinant expressing a foreign gene product is followed by a boost using a purified subunit preparation form of that gene product, elicits an enhanced immune response relative to the response elicited with either product alone. Human volunteers immunized with a vaccinia recombinant expressing the HIV-1 envelope glycoprotein and boosted with purified HIV-1 envelope glycoprotein subunit preparation exhibit higher HIV-1 neutralizing antibody titers than individuals immunized with just the vaccinia recombinant or purified envelope glycoprotein alone (Graham et al., 1993; Cooney et al., 1993). Humans immunized with two injections of an ALVAC-HIV-1 env recombinant (vCP125) failed to develop HIV specific antibodies. Boosting with purified rgp160 from a vaccinia virus recombinant resulted in detectable HIV-1 neutralizing antibodies. Furthermore, specific lymphocyte T cell proliferation to rgp160 was clearly increased by the boost with rgp160. Envelope specific cytotoxic lymphocyte activity was also detected with this vaccination regimen (Pialoux et al., 1995). Macaques immunized with a vaccinia recombinant expressing the simian immunodeficiency virus (SIV) envelope glycoprotein and boosted with SIV envelope glycoprotein from a baculovirus recombinant are protected against a SIV challenge (Hu et al., 1991; 1992). In the same fashion, purified HCMvgB protein can be used in prime/boost protocols with NYVAC or ALVAC-gB recombinants. NYVAC, ALVAC and TROVAC have also been recognized as unique among all poxviruses in that the National Institutes of Health ("NIH")(U.S. Public Health Service), Recombinant DNA Advisory Committee, which issues guidelines for the physical containment of genetic material such as viruses and vectors, i.e., guidelines for safety procedures for the use of such viruses and vectors which are based upon the pathogenicity of the particular virus or vector, granted a reduction in physical containment level: from BSL2 to BSL1. No other poxvirus has a BSL1 physical containment level. Even the Copenhagen strain of vaccinia virus--the common smallpox vaccine--has a higher physical containment level; namely, BSL2. Accordingly, the art has recognized that NYVAC, ALVAC and TROVAC have a lower pathogenicity than any other poxvirus. ALVAC, TROVAC, and NYVAC were deposited under the terms of the Budapest Treaty with the American Type Culture Collection (ATCC), 12301 Parklawn Drive, Rockville, Md., 20852, USA: NYVAC under ATCC accession number VR-2559 on Mar. 6, 1997; TROVAC under ATCC accession number VR-2553 on Feb. 6, 1997 And, ALVAC under ATCC accession number VR-2547 on Nov. 14, 1996. CMV is a frequent cause of morbidity and mortality in AIDS patients, bone marrow transplant recipients, and patients undergoing immunosuppressive therapies for neoplastic diseases. There is no effective, well-tolerated, pharmaceutical therapy for CMV infection. One approach might be the ex vivo stimulation of donor CMV-specific CTLs for the treatment and control of the often fatal pneumonia caused by CMV infection in the bone marrow transplant recipient. In fact, the treatment and control of CMV infection in man by adoptive transfer of CMV CTL clones has been successfully demonstrated (Riddell et al., 1992). However, in this instance, CMV was used to stimulate and maintain the CMV-specific CTL clones used in this therapeutic protocol. The use of CMV for the purpose of ex vivo stimulation of CTL clones has its drawbacks, the most obvious being the possibility of introducing additional CMV into an immunosuppressed patient. The availability of immunotherapeutic agents that provide a safe and acceptable means for stimulating antigen-specific cellular immune effector activities seems to be a major shortcoming in the field of adoptive immunotherapy. Protein subunits, although potentially safe, are notoriously poor at stimulating CTLS. Peptides, generally considered safe yet effective at stimulating a CTL response, are highly restrictive in their abilities to stimulate CTL responses. Peptides are typically capable of inducing a CTL response to only one CTL epitope of many possible CTL epitopes contained within a single protein. Furthermore, peptides typically stimulate CTL responses from only a restricted portion of the population, being restricted to only those individuals expressing a particular allele of the human major histocompatibility complex (MHC). Recombinant virus vectors are considered excellent inducers of CTL reactivities since they are capable of expressing the entire antigen, thus not restricted to a single epitope for a single segment of the population. However, most of these virus vectors, such as adenovirus, are capable of replication and are not considered safe for use in this type of protocol. Since ALVAC recombinants do not replicate in mammalian cells, yet are capable of stimulating antigen-specific CTL responses, as demonstrated by data contained within this application, ALVAC recombinants represent a uniquely safe and effective method for the ex vivo stimulation of virus-specific CTL clones for utilization in immunotherapeutic applications. This invention pertains to NYVAC, ALVAC and vaccinia (WR strain) recombinants containing the HCMV genes encoding for gB, gH, gL, pp150, pp65 and IE 1, including truncated versions thereof, which are further described in the Examples below. Clearly based on the attenuation profiles of the NYVAC, ALVAC, and TROVAC vectors and their demonstrated ability to elicit both humoral and cellular immunological responses to extrinsic immunogens (Tartaglia et al., 1993a,b; Taylor et al., 1992; Konishi et al., 1992) such recombinant viruses offer a distinct advantage over previously described vaccinia-based recombinant viruses. The administration procedure for recombinant virus or expression product thereof, compositions of the invention such as immunological, antigenic or vaccine compositions or therapeutic compositions can be via a parenteral route (intradermal, intramuscular or subcutaneous). Such an administration enables a systemic immune response. More generally, the inventive antigenic, immunological or vaccine compositions or therapeutic compositions (compositions containing the poxvirus recombinants of the invention) can be prepared in accordance with standard techniques well known to those skilled in the pharmaceutical art. Such compositions can be administered in dosages and by techniques well known to those skilled in the medical arts taking into consideration such factors as the age, sex, weight, and condition of the particular patient, and the route of administration. The compositions can be administered alone, or can be co-administered or sequentially administered with compositions of the invention or with other immunological, antigenic or vaccine or therapeutic compositions in seropositive individuals. The compositions can be administered alone, or can be co-administered or sequentially administered with compositions of the invention or with other antigenic, immunological, vaccine or therapeutic compositions in seronegative individuals. Such other compositions can include purified antigens from HCMV or from the expression of such antigens by a recombinant poxvirus or other vector system or, such other compositions can include a recombinant poxvirus which expresses other HCMV antigens or biological response modifiers again taking into consideration such factors as the age, sex, weight, and condition of the particular patient, and, the route of administration. Examples of compositions of the invention include liquid preparations for orifice, e.g., oral, nasal, anal, vaginal, etc., administration such as suspensions, syrups or elixirs; and, preparations for parenteral, subcutaneous, intradermal, intramuscular or intravenous administration (e.g., injectable administration) such as sterile suspensions or emulsions. In such compositions the recombinant poxvirus may be in admixture with a suitable carrier, diluent, or excipient such as sterile water, physiological saline, glucose or the like. Further, the products of expression of the inventive recombinant poxviruses can be used directly to stimulate an immune response in either seronegative or seropositive individuals or in animals. Thus, the expression products can be used in compositions of the invention instead or in addition to the inventive recombinant poxvirus in the aforementioned compositions. Additionally, the inventive recombinant poxvirus and the expression products therefrom stimulate an immune or antibody response in humans and animals and therefore those products are antigens. From those antibodies or antigens, by techniques well-known in the art, monoclonal antibodies can be prepared and, those monoclonal antibodies or the antigens, can be employed in well known antibody binding assays, diagnostic kits or tests to determine the presence or absence of particular HCMV antigen(s) and therefore the presence or absence of the virus or expression of the antigen(s) (in HCMV or other systems), or to determine whether an immune response to the virus or antigen(s) has simply been stimulated. Those monoclonal antibodies or the antigens can also be employed in immunoadsorption chromatography to recover or isolate HCMV or expression products of the inventive recombinant poxvirus. More in particular, the inventive recombinants and compositions have numerous utilities, including: (i) inducing an immunological response in seronegative individuals (use as or as part of a vaccine regimen); (ii) therapy in seropositive individuals; and (iii) a means for generating HCMV protein in vitro without the risk of virus infection. The products of expression of the inventive recombinant poxvirus can be used directly to stimulate an immune response in either seronegative or seropositive individuals or in animals. Thus, the expression products can be used in compositions of the invention instead of or in addition to the inventive recombinant poxvirus. Additionally, the inventive recombinant poxvirus and the expression products therefrom stimulate an immune or antibody response in humans and animals. From those antibodies, by techniques well-known in the art, monoclonal antibodies can be prepared and, those monoclonal antibodies or the expression products of the inventive poxvirus and composition can be employed in well known antibody binding assays, diagnostic kits or tests to determine the presence or absence of particular HCMV antigen(s) or antibody(ies) and therefore the presence or absence of the virus, or to determine whether an immune response to the virus or antigen(s) has simply been stimulated. Those monoclonal antibodies can also be employed in immunoadsorption chromatography to recover, isolate or detect HCMV or expression products of the inventive recombinant poxvirus. Methods for producing monoclonal antibodies and for uses of monoclonal antibodies, and, of uses and methods for HCMV antigens--the expression products of the inventive poxvirus and composition--are well known to those of ordinary skill in the art. They can be used in diagnostic methods, kits, tests or assays, as well as to recover materials by immunoadsorption chromatography or by immunoprecipitation. Monoclonal antibodies are immunoglobulins produced by hybridoma cells. A monoclonal antibody reacts with a single antigenic determinant and provides greater specificity than a conventional, serum-derived antibody. Furthermore, screening a large number of monoclonal antibodies makes it possible to select an individual antibody with desired specificity, avidity and isotype. Hybridoma cell lines provide a constant, inexpensive source of chemically identical antibodies and preparations of such antibodies can be easily standardized. Methods for producing monoclonal antibodies are well known to those of ordinary skill in the art, e.g., Koprowski, H. et al., U.S. Pat. No. 4,196,265, issued Apr. 1, 1989, incorporated herein by reference. Uses of monoclonal antibodies are known. One such use is in diagnostic methods, e.g., David, G. and Greene, H. U.S. Pat. No. 4,376,110, issued Mar. 8, 1983; incorporated herein by reference. Monoclonal antibodies have also been used to recover materials by immunoadsorption chromatography, e.g., Milstein, C. 1980, Scientific American 243:66, 70, incorporated herein by reference. Furthermore, the inventive recombinant poxvirus or expression products therefrom can be used to stimulate a response in cells in vitro or ex vivo for subsequent reinfusion into a patient. If the patient is seronegative, the reinfusion is to stimulate an immune response, e.g., an immunological or antigenic response such as active immunization. In a seropositive individual, the reinfusion is to stimulate or boost the immune system against HCMV. Accordingly, the inventive recombinant poxvirus has several utilities: In antigenic, immunological or vaccine compositions such as for administration to seronegative individuals. In therapeutic compositions in seropositive individuals in need of therapy to stimulate or boost the immune system against HCMV. In vitro to produce antigens which can be further used in antigenic, immunological or vaccine compositions or in therapeutic compositions. To generate antibodies (either by direct administration or by administration of an expression product of the inventive recombinant poxvirus) or expression products or antigens which can be further used: in diagnosis, tests or kits to ascertain the presence or absence of antigens in a sample such as sera, for instance, to ascertain the presence or absence of HCMV in a sample such as sera or, to determine whether an immune response has elicited to the virus or, to particular antigen(s); or, in immunoadsorption chromatography, immunoprecipitation and the like. Furthermore, the recombinant poxviruses of the invention are useful for generating DNA for probes or for PCR primers which can be used to detect the presence or absence of hybridizable DNA or to amplify DNA, e.g., to detect HCMV in a sample or for amplifying HCMV DNA. Other utilities also exist for embodiments of the invention. A better understanding of the present invention and of its many advantages will be had from the following examples, given by way of illustration. |
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