Submitted to: International Conference on Negative Strand Viruses
Publication Type: Abstract Only
Publication Acceptance Date: 5/17/2006
Publication Date: 6/17/2006
Citation: Richt, J.A., Lekcharoensuk, P., Lager, K.M., Vincent, A.L., Ma, W., Loiacono, C.M., Wu, W.H., Webby, R.J., Solorzano, A., Garcia-Sastre, A. 2006. Vaccination of pigs against swine influenza viruses using a NS1-deleted modified live vaccine [abstract]. 13th International Conference on Negative Strand Viruses. Paper No. 277. p. 198.
Technical Abstract: Swine influenza virus (SIV), a member of the genus influenza A virus, can naturally infect pigs and be transmitted to humans. In the pig, genetic reassortment to create novel influenza subtypes by mixing avian, human and swine influenza viruses is possible. A vaccine inducing cross-protective immunity between different influenza subtypes is highly desirable. Previously, we have shown that a H3N2 SIV (TX/98) containing a modified NS1 gene expressing a truncated NS1 protein of 126 amino acids, NS1del126, was attenuated in swine. In this study, 3- or 4-week-old pigs were vaccinated and boosted with the TX98 NS1del126 modified live virus (MLV). Nine to 14 days after boosting, pigs were challenged with wild type homologous H3N2 or heterosubtypic H1N1 SIVs and necropsied 5 days later. The MLV was highly attenuated and completely protected against challenge with the homologous virus, independent of whether pigs were vaccinated via the intratracheal, intranasal or the intramuscular route. Vaccinated pigs challenged with the heterosubtypic H1N1 virus demonstrated pathological changes similar to the non-vaccinated H1N1 control pigs. Remarkably, vaccinated pigs challenged with H1N1 had significantly reduced virus shedding from the respiratory tract when compared to non-vaccinated, H1N1 challenged pigs. All vaccinated pigs developed a significant level of HI titer, serum IgG and mucosal IgA antibodies against H3N2 SIV antigens. All vaccinated pigs were seronegative for NS1, indicating the potential use of the TX98 NS1del126 MLV as a DIVA vaccine to differentiate infected from vaccinated animals.