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Title: Presence of interferon-alpha delays viral replication and reduces disease signs in pigs challenged with porcine reproductive and respiratory syndrome virus

Author
item Brockmeier, Susan
item Lager, Kelly
item Grubman, Marvin
item BROUGH, DOUGLAS - GEN VEC INC.
item ETTYREDDY, DAMODAR - GEN VEC INC.
item Sacco, Randy
item Gauger, Phillip
item Lehmkuhl, Howard

Submitted to: Porcine Reproductive and Respiratory Syndrome International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 9/8/2006
Publication Date: 12/1/2006
Citation: Brockmeier, S.L., Lager, K.M., Grubman, M.J., Brough, D., Ettyreddy, D., Sacco, R.E., Gauger, P.C., Lehmkuhl, H.D. 2006. Presence of interferon-alpha delays viral replication and reduces disease signs in pigs challenged with porcine reproductive and respiratory syndrome virus. Proceeding of the International PRRS Symposium, December 1-2, 2006, Chicago, Illinois. p. 27.

Interpretive Summary:

Technical Abstract: Compared to other viruses that infect the respiratory system, porcine reproductive and respiratory syndrome virus (PRRSV) appears to induce only modest levels of interferon-alpha (IFNA). However, IFNA has been shown to inhibit PRRSV replication in vitro, and indirectly to inhibit replication in vivo by decreasing replication of PRRSV in pigs coinfected with viruses that induce high levels of IFNA. In this study, pigs were injected with an advanced generation, nonreplicating adenovirus vector expressing porcine IFNA (AdIFNA) and then challenged with PRRSV to determine more directly whether the presence of increased levels of IFNA would decrease viral replication and/or disease. Groups of 10 pigs each were inoculated with AdIFNA and not challenged, AdIFNA and challenged with PRRSV 1 day later, or inoculated with the same adenovirus that does not express IFNA (Adnull) and challenged 1 day later with PRRSV. IFNA levels in all pigs inoculated with the AdIFNA were elevated the day of challenge (1 day after inoculation) but were undetectable by 3 days after inoculation in the pigs that were not challenged with PRRSV. Pigs inoculated with AdIFNA and challenged with PRRSV had lower febrile responses, decreased percentage of lung involvement at 10 days post infection, decreased hyperplasia of the lymph nodes at 10 days post infection, delayed viremia and antibody response, and higher serum IFNA levels as a result of PRRSV infection, as compared to pigs inoculated with Adnull and challenged with PRRSV. These results indicate that interferon-alpha can have protective effects if present during the time of infection with PRRSV.