Claims
- 1. In a multiple-passage method for attenuating a virus including the steps of successively replicating said virus through inoculation and replication of the virus in respective individual cell cultures until attenuation is achieved, the improvement which comprises removing virus-containing samples from at least certain of said cell cultures while the virus is replicating at a logarithmic rate and prior to induction of cytopathic effects in said certain cell cultures, and inoculating the next respective cell culture passages with said samples.
- 2. The method of claim 1, said removing step occuring approximately 24 hours after inoculation of said cell cultures.
- 3. The method of claim 1, said cell culture comprising a monolayer of cells being greater than about 70% confluent.
- 4. The method of claim 1 further comprising the step of periodically testing said progeny virus for attenuation.
- 5. The method of claim 1 further comprising the steps of retaining said certain cell cultures after said removal step, and observing whether induction of cytopathic effects occurs in said retained cell cultures.
- 6. The method of claim 1, said inoculation comprising the smallest number of viruses which ultimately results in CPE.
- 7. A PRRS virus having ATCC Accession Number VR-2638.
- 8. A virus attenuated by the method of claim 1.
- 9. The virus of claim 8, said virus having been passaged a minimum of 200 times in cell culture.
- 10. The virus of claim 9, said virus being substantially avirulent.
- 11. The virus of claim 10, said virus capable of eliciting antibody response in swine.
- 12. The virus of claim 11, said antibody response being specific for porcine reproductive and respiratory syndrome virus strains.
- 13. A vaccine comprising the virus of claim 7.
- 14. The vaccine of claim 13 further comprising a pharmacologically compatible carrier agent.
- 15. The vaccine of claim 13, said vaccine capable of eliciting antibody response in a host animal.
- 16. The vaccine of claim 15, said host animal including swine.
- 17. The vaccine of claim 15, said antibody response being specific to porcine reproductive and respiratory syndrome virus strains.
- 18. The vaccine of claim 17, said strains including atypical porcine reproductive and respiratory syndrome strains.
- 19. A virus having a restriction enzyme cleavage pattern of 1-4-2 by the enzymes MLU 1, Hinc II, and Sac II, respectively, in open reading frame five.
- 20. The virus of claim 19 not being cleavable by MLU 1 in open reading frame five.
- 21. A vaccine comprising the virus of claim 19.
- 22. The vaccine of claim 21 further comprising a pharmacologically compatible carrier agent.
- 23. The vaccine of claim 21, said vaccine capable of eliciting antibody response in a host animal.
- 24. The vaccine of claim 23, said host animal including swine.
- 25. The vaccine of claim 23, said antibody response being specific to porcine reproductive and respiratory syndrome virus strains.
- 26. The vaccine of claim 25, said strains including atypical porcine reproductive and respiratory syndrome.
- 27. A method of immunizing swine against porcine reproductive and respiratory syndrome virus strains, said method comprising the step of administering to swine the vaccine of claim 21.
- 28. An isolated DNA sequence having at least about 65% sequence identity with SEQ ID No. 1.
- 29. An isolated DNA sequence having at least about 75% sequence homology with SEQ ID No. 1.
- 30. An isolated DNA sequence having at least about 65% sequence identity with SEQ ID No. 2.
- 31. An isolated DNA sequence having at least about 75% sequence homology with SEQ ID No. 2.
- 32. A PRRS virus including the sequence of claim 28.
- 33. A PRRS virus including the sequence of claim 29.
- 34. The virus of claim 33, said virus being attenuated by the method of claim 1.
- 35. The virus of claim 33, said virus having been passaged a minimum of 200 times in cell culture.
- 36. The virus of claim 33, said virus being attenuated.
- 37. The virus of claim 33, said virus being substantially avirulent.
- 38. The virus of claim 33, said virus capable of eliciting antibody response in swine.
- 39. The virus of claim 38, said antibody response being specific for porcine reproductive and respiratory syndrome virus strains.
- 40. A vaccine comprising the DNA sequence of claim 29.
- 41. The vaccine of claim 40 further comprising a pharmacologically compatible carrier agent.
- 42. The vaccine of claim 40, said vaccine capable of eliciting antibody response in a host animal.
- 43. The vaccine of claim 42, said host animal including swine.
- 44. The vaccine of claim 43, said antibody response being specific to porcine reproductive and respiratory syndrome virus strains.
- 45. The vaccine of claim 44, said strains including atypical porcine reproductive and respiratory syndrome strains.
- 46. The DNA sequence of claim 29 wherein administration of said sequence to a host animal confers effective immunity.
RELATED APPLICATION
[0001] This is a continuation of application Ser. No. 09/461,879, filed Dec. 15, 1999, which is a continuation-in-part of application Ser. No. 09/298,110 filed Apr. 22, 1999.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09461879 |
Dec 1999 |
US |
Child |
10143186 |
May 2002 |
US |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09298110 |
Apr 1999 |
US |
Child |
09461879 |
Dec 1999 |
US |