| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | September 8, 1998 |
| PATENT TITLE |
Vaccine comprising an infectious bursal disease virus MB, MB-1 or MB-2 strain |
| PATENT ABSTRACT |
Invention relates to a vaccine for the prevention of Infectious Bursal Disease in poultry comprising an effective immunizing amount of a live attenuated intermediately-pathogenic IBD virus belonging to the strain deposited at the ECACC under No. V92052301 (MB), an effective immunizing amount of a live attenuated intermediately-pathogenic IBD virus belonging to the strain deposited at the ECACC under No. V92100106 (MB-2), or an effective immunizing amount of a live attenuated intermediately-pathogenic IBD virus belonging to the strain deposited at the ECACC under No. V92102209 (MB-1). |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | November 30, 1993 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED |
Snyder et al. Avian Pathology 19:419-423 1990. Kibenge et al., "Biochemistry and Immunology of Infectious Bursal Disease Virus", J. Gen. Virol. (Great Britain) 69:1757-1775 (1988). |
| PATENT CLAIMS |
What is claimed is: 1. A lyophilized virus composition containing an attenuated strain of the Infectious Bursal Disease virus deposited at the ECACC under NO. V92052301 (MB). 2. A lyophilized virus composition containing an attenuated strain of the Infectious Bursal Disease virus deposited at the ECACC under NO. V92100106 (MB-2). 3. A lyophilized virus composition containing an attenuated strain of the Infectious Bursal Disease virus deposited at the ECACC under NO. V92102209 (MB-1). 4. A vaccine for the prevention of Infectious Bursal Disease in poultry comprising an effective immunizing amount of a live attenuated intermediately pathogenic Infectious Bursal Disease virus belonging to the strain deposited at the ECACC under No. V92052301 (MB). 5. A vaccine for the prevention of Infectious Bursal Disease in poultry comprising an effective immunizing amount of a live attenuated intermediately pathogenic Infectious Bursal Disease virus belonging to the strain deposited at the ECACC under No. V92100106 (MB-2). 6. A vaccine for the prevention of Infectious Bursal Disease in poultry comprising an effective immunizing amount of a live attenuated intermediately pathogenic Infectious Bursal Disease virus belonging to the strain deposited at the ECACC under No. V92102209 (MB-1). 7. A vaccine for the prevention of Infectious Bursal Disease in poultry comprising an effective immunizing amount of at least one live attenuated Infectious Bursal Disease virus selected from the group consisting of the strains deposited at the ECACC under Nos. V92052301 (MB), V92100106 (MB-2) and V92102209 (MB-1). 8. A vaccine for poultry comprising: a) an effective immunizing amount of at least one live attenuated Infectious Bursal Disease virus selected from the group consisting of the strains deposited at the ECACC under Nos. V92052031 (MB), V92100106 (MB-2), and V92102209 (MB-1); and b) an effective immunizing amount of at least one additional poultry disease virus other than Infectious Bursal Disease Virus (IBDV). 9. A vaccine for poultry according to claim 8 wherein said additional poultry disease virus is selected from the group consisting of Lentogenic New Castle Disease virus, Marek Disease virus, and Infectious Bronchitis virus. 10. A method of protecting poultry against Infectious Bursal Disease which comprises administering to the birds an effective immunizing amount of a vaccine selected from the group consisting of a vaccine according to claim 7 and a vaccine according to claim 7 with at least one additional poultry disease virus other than Infectious Bursal Disease Virus (IBDV). 11. A method according to claim 10 wherein said effective immunizing amount is from about 10.sup.1 to 10.sup.4 EID.sub.50 per dose. 12. A method of protecting poultry and, which comprises administering to the chickens an effective immunizing amount of a vaccine according claim 9. 13. A method according to claim 10 which comprises a single administration at any age of vaccination. 14. A method according to claim 10 which comprises repeated administrations of the vaccine. 15. A method according to claim 10 or 12 wherein said vaccine is administered via drinking water. 16. A method according to claim 10 or 12 wherein said vaccine is administered as eyedrops via the ocular route. 17. A method according to claim 10 or 12 wherein said vaccine is administered as nose drops via the nasal route. 18. A method according to claim 10 or 12 wherein said vaccine is administered by spraying the birds with said vaccine. 19. A method for the preparation of a live vaccine which protects poultry against Infectious Bursal Disease comprising the steps of: (a) growing an Infectious Bursal Disease virus in a medium selected from the group consisting of specific pathogenic free (SPF) embryonated chicken eggs, chicken embryo fibroblasts (CEF) and Vero cell line; (b) harvesting the virus material obtained under step (a); (c) stabilizing the material obtained in step (b); and (d) lyophilizing the material obtained in step (c); wherein the Infectious Bursal Disease virus grown in step (a) is a virus of one of the strains selected from the group consisting of MB (ECACC Deposit No. V92052301), MB-1 (EACC Deposit No. 92102209) and MB-2 ECACC Deposit No. 92100106). |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION The invention concerns novel Infectious Bursal Disease (IBD) vaccines and novel Infectious Bursal Disease attenuated viral strains. BACKGROUND OF THE INVENTION Infectious Bursal Disease in poultry is caused by a virus which belongs to the BIRNA group of viruses. These viruses are relatively stable at low pH, ether and chloroform. They contain two fragments of double-stranded RNA which encode their viral proteins. Two serotypes are known, namely Serotype I, which causes the IBD in chickens and serotype II, isolated from turkeys, not pathogenic to chickens. Maternal antibodies to one serotype do not protect against the other serotype. Homologous antibodies do, however, protect chicks against the disease. Infectious Bursal Disease is widespread and causes great economic losses. Afflicted chickens suffer from diarrhea, muscular hemorrhage, necrosis of the bursa of Fabricius and severe damage to the immune system. The mortality is high and the surviving chickens exhibit growth retardation and high sensitivity to other diseases. Several live attenuated vaccines were developed over the years. For example, U.S. Pat. No. 3,584,055 discloses a vaccine effective against IBD containing attenuated IBD virus obtained through multiple passages. U.S. Pat. No. 3,769,400 discloses a vaccine effective against IBD containing attenuated IBD virus obtained through passages in baby mice. U.S. Pat. No. 4,530,831 discloses a live or inactivated vaccine effective against IBD in poultry on a single administration to the birds at the usual age of vaccination, which comprises IBD virus deposited as ATCC VR-2041. The vaccine is non-pathogenic and can break through the usual level of maternally derived antibodies without damage to the bursa of the maternally immune birds, and is therefore used to confer protection to poultry. The vaccine is obtained by a 4-step plaque purification, followed by two egg passages. U.S. Pat. No. 4,824,668 discloses a vaccine effective against IBD in poultry comprising an attenuated or inactivated IBD virus strain VR2161 and a carrier or diluent, which can be administered to poultry without producing IBD symptoms in the vaccinated birds. Such vaccines were usually administered via drinking water, and, until 1988, they conferred good immunity. PCT Application WO 9001336 discloses a vaccine for preventing IBD in poultry caused by strains not responsive to vaccines known at the time (apparently "non-classic" strains), containing a killed or attenuated novel purified IBD virus as described therein. In 1988, first in England and Holland and afterwards in other parts of the world, a new strain appeared which was very pathogenic and caused much higher mortality rates than those caused by the "old" strains. The existing live attenuated vaccines no longer protected against the new strain. The new strain isolated in Europe was not found to be antigenically different from the old, so-called "classic" strain. On the other hand, in the U.S. "variant" strains were isolated that differ from the "classic" strains when tested with monoclonal antibodies test systems. The Israeli isolates which are the subject of this invention were tested and found to be similar to the European strains. The inefficiency of the old vaccines to protect against the new strains is caused, inter alia, by the higher pathogenicity of the new strains capable of penetrating through the maternal antibodies transferred from breeder hens to chicks. Upon vaccination of the newly hatched chicks the viruses of the old thus introduced are inactivated by such maternal antibodies. The maternal antibody titer decreases after hatching with a half-life of about 5 days. If vaccination is postponed to an age at which no maternal antibodies can be detected, the chickens are at a very high risk: they may be infected by a pathogenic field strain before being immunized by the vaccine strain. It is therefore believed that a vaccine strain should have some pathogenicity, so that it would break through maternal antibodies before field strains do, namely it should be of an intermediate virulence. Recently, H. J. Tsai and Y. M. Saif ›Avian Diseases 36:415-422 (1992)! described two variant strains of IBD (IN and E), which were adapted and passaged in an established green monkey kidney cell line (BGM-70). Passage in cell culture resulted in loss of pathogenicity, while antigenicity and immunogenicity were maintained. However, no protection against the disease was induced when the passaged viruses were given to specific-pathogen-free (SPF) chickens as live vaccines. In contrast, the present invention relates to viruses which were passaged, lost some of their pathogenicity, but retained antigenicity and do confer immunity to poultry. SUMMARY OF THE INVENTION The invention relates to a vaccine for the prevention of Infectious Bursal Disease in poultry comprising an effective immunizing amount of a live attenuated intermediately-pathogenic IBD virus belonging to the strain deposited at the ECACC under No. V92052301 (MB). The invention also relates to a vaccine for the prevention of Infectious Bursal Disease in poultry comprising an effective immunizing amount of a live attenuated intermediately-pathogenic IBD virus belonging to the strain deposited at the ECACC under No. V92100106 (MB-2). The invention further relates to a vaccine for the prevention of Infectious bursal disease in poultry comprising an effective immunizing amount of a live attenuated intermediately-pathogenic IBD virus belonging to the strain deposited at the ECACC under No. V92102209 (MB-1). In addition, the invention relates to a method of preventing Infectious Bursal disease in poultry by administering to the birds an effective immunizing amount of a vaccine containing the IBD virus of the strains deposited at the ECACC under No. V92052301 (MB) and/or No. 92100106 (MB-2) and/or No. V92102209 (MB-1). In a further aspect, the invention relates to three novel virus strains deposited at the ECACC under No. V92052301 (MB), under No. V92100106 (MB-2) and under No. V92102209 (M-1). BRIEF DESCRIPTION OF THE DRAWINGS Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: FIG. 1 is a picture of a western blot analysis. DETAILED DESCRIPTION OF THE INVENTION Furthermore, the invention relates to a method of preparing live vaccines which protect poultry against Infectious Bursal Disease, containing an effective immunizing amount of a virus of the strain deposited at the ECACC under No. V92052301 (MB) and/or No. V92100106 (MB-2) and/or No. V92102209 (MB-1). DETAILED DESCRIPTION OF THE INVENTION The invention relates to three novel virus strains deposited at the ECACC under No. V92052301 (MB), under No. V92100106 (MB-2) and under No. V92102209 (MB-1). The deposit was at the ECACC (European Collection of Animal Cell Cultures), PHLS Centre for Applied Microbiology & Research, Porton Down, Salisbury, Wilts, SP4 OJG, U.K. As stated above, vaccination of poultry should be effected at an early age, before disappearance of maternal antibodies, to avoid exposure of chicks to the high risk of being infected by pathhogenic field strains. Therefore it is believed that a potent vaccine strain should maintain some pathogenicity, so that it would break through maternal antibodies. The three novel strains of the invention, MB, MB-2 and MB-1, pose this desired characteristic, being intermediately pathogenic, thus breaking through maternal immunity, but not so virulent as to cause disease. When tested in SPF chicks free of IBD antibodies, strain MB-1 was somewhat less pathogenic than strain MB, and strain MB-2 even less pathogenic. All three strains confer good immunity when administered, via drinking water, even at the early age of 1-2 weeks and are non-pathogenic for maternally immune broiler chicks or replacement breeder and layer chicks. A certain degree of bursal atrophy does however occur following vaccination. The original strains were isolated from bursae of Fabricius of broiler chickens that died of IBD on two farms in the central part of Israel during the year of 1989. The virus can be grown in embryonated chicken eggs, as well as in cell cultures such as chicken embryo fibroblast (CEF) tissue culture, vero cell line cultures and other suitable cultures. Cells are grown to 80% confluency on roller bottles, flasks, microcarriers or other methods serving for growing tissue cultures. 3-4 days following infection, cytopathic effect (CPE) is formed and the virus is harvested by freezing and thawing, followed by low speed centrifugation. Stabilizers are added to the supernatant for freeze drying process. Attenuation and propagation of the virus will be described in detail in the following Examples. Preparation of vaccines and their administration is also within the scope of the invention. Embryonated eggs were inoculated, the embryos and membranes harvested and a live vaccine prepared from a homogenate prepared from them with the addition of a stabilizer normally used in live avian vaccines such as peptone, lactose, dry powdered milk, etc. A dosage may be used, as live vaccine, in the range of 10.sup.2 -10.sup.4 EID.sub.50 (EID.sub.50 =egg infective dose 50%). A live vaccine according to the invention can contain a single of said virus strains, or a mixture of any two of said strains, or further, a mixture of all said virus strains. Any of the live vaccines of the invention may also contain other viruses, e.g., New Castle virus or Marek Disease virus or Infectious Bronchitis virus. The vaccine is administered to chickens by presently available inoculation techniques, for example, via drinking water, through ocular administration as eye drops, aerosol or other spraying methods, through nasal administration as nose drops and any other suitable known vaccination routes. Chickens vaccinated with live vaccine containing the MB and/or MB-2 and/or MB-1 viruses respond with precipitating and type specific neutralizing antibodies and they were immune to subsequent infection with an Israeli virulent IBD virus strain, as well as infection with a European strain. Thus, vaccines according to the invention appear to confer universal immunity against IBD. The above discussion provides a factual basis for the use of novel virus strains as a vaccine against infectious bursal disease in poultry. The methods used with, and the utility of, the present invention can be shown by the following examples. |
| PATENT EXAMPLES | This data is not available for free |
| PATENT PHOTOCOPY | Available on request |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |