Location: Virus and Prion ResearchTitle: Heterologous challenge in the presence of maternally-derived antibodies results in vaccine-associated enhanced respiratory disease in weaned piglets
|RAJAO, DANIELA - Non ARS Employee|
|SANDBULTE, MATTHEW - Iowa State University|
|GAUGER, PHILLIP - Iowa State University|
|PLATT, RATREE - Iowa State University|
|ROTH, JAMES - Iowa State University|
|PEREZ, DANIEL - University Of Georgia|
Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2016
Publication Date: 4/1/2016
Citation: Rajao, D.S., Sandbulte, M.R., Gauger, P.C., Kitikoon, P., Platt, R., Roth, J.A., Perez, D.R., Loving, C.L., Vincent, A.L. 2016. Heterologous challenge in the presence of maternally-derived antibodies results in vaccine-associated enhanced respiratory disease in weaned piglets. Virology. 491:79-88.
Interpretive Summary: Infection with influenza A virus (IAV) results in one of the most important respiratory diseases of swine. Whole inactivated virus (WIV) vaccines are widely used in the swine industry to reduce disease against IAV infection and are commonly used in breeding females to provide maternal-derived antibodies (MDA) through colostrum in an effort to transfer passive immunity from sow to piglets. However, MDA can potentially still allow IAV infection, clinical disease, and transmission while preventing active immunity to WIV used in weaned piglets with MDA. The combination of a wide variety of IAV circulating among swine in the United States with the extensive use of WIV in sows creates potential conditions for the occurrence of vaccine-associated enhanced respiratory disease (VAERD) with the vaccine strain is mismatched to the infecting strain. Here, we evaluated whether MDA from vaccinated sows could protect or potentiate infection with mismatched challenge strains of virus in piglets. Piglets with high levels of MDA elicited by vaccinating the sow with WIV showed reduced matched virus infection, transmission, and disease. However, piglets with WIV-derived MDA challenged with mismatched virus developed VAERD of intermediate severity. MDA derived from boosting sows’ natural immunity with wild type virus did not protect piglets against heterologous challenge; however, it did not result in VAERD. These results suggest that the MDA derived from inactivated vaccines and transferred to the litters could have important implications on the disease outcome and should be considered when developing vaccination protocols in breeding sow herds.
Technical Abstract: Control of influenza A virus (IAV) in pigs is done by vaccination of females to provide maternally-derived antibodies (MDA) through colostrum. Our aim was to evaluate if MDA interfere with IAV infection, clinical disease, and transmission in non-vaccinated piglets. In a first study, naïve sows were vaccinated with H1N2-delta1 whole inactivated virus (WIV) vaccine. In a follow-up study seropositive sows to 2009 pandemic H1N1 (H1N1pdm09) were boosted with H1N1pdm09 WIV or secondary experimental infection (EXP). MDA-positive pigs were challenged with homologous or heterologous virus, and MDA-negative control groups were included. WIV-MDA piglets were protected from homologous infection. However, piglets with WIV-derived MDA subsequently challenged with heterologous virus developed vaccine associated enhanced respiratory disease (VAERD), regardless of history of natural exposure in the sows. Our data indicates that although high titers of vaccine-derived MDA reduced homologous virus infection, transmission, and disease, MDA alone was sufficient to induce VAERD upon heterologous infection.