Alphavirus-vectored HA subunit vaccine provides partial protection against heterologous challenge in pigs

Authors: Abente, Eugenio; RAJAO, DANIELA - Non ARS Employee; GAUGER, PHILLIP - Iowa State University; Baker, Amy

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2018
Publication Date: 3/7/2019
Citation: Abente, E.J., Rajao, D.S., Gauger, P.C., Vincent, A.L. 2019. Alphavirus-vectored hemagglutinin subunit vaccine provides partial protection against heterologous challenge in pigs. Vaccine. 37(11):1533-1539. https://doi.org/10.1016/j.vaccine.2018.12.071.
DOI: https://doi.org/10.1016/j.vaccine.2018.12.071

Interpretive Summary: It is challenging to develop a broadly protective vaccine against influenza virus in swine because the genetic and antigenic diversity is large. Effective use of vaccines can help reduce the burden of disease caused by continued circulation of influenza and there are multiple vaccine platforms commercially available. In an experimental vaccine challenge study, we compared monovalent and bivalent alphavirus-vectored hemagglutinin (HA) subunit vaccines. We found that monovalent HA vaccines provided efficient protection against antigenically distinct HA viruses and that bivalent vaccines elicited an antibody response to both antigens and provided efficient protection. Examining the efficacy of available vaccine platforms will help inform swine producers on how to best implement vaccine use to reduce influenza A virus (IAV) infections in swine.

Technical Abstract: Influenza A virus in swine (IAV-S) is an important pathogen in pigs in the United States, in addition to posing a potential risk to humans through zoonotic events. Intervention strategies continue to be explored to better control virus circulation. Improved surveillance efforts have led to significantly increased sequence data available on circulating strains, vastly improving our understanding of the genetic and antigenic diversity of IAV-S. IAV-S in North America is characterized by repeated spillover events of human viruses into pigs followed by genetic and antigenic diversification. An important gap that needs to be addressed is our understanding of the role that various vaccine platforms have on efficacy against antigenically heterologous challenge. Currently licensed vaccines often update their components to adapt to a dynamic antigenic landscape and newly developed technologies continue to be approved. Hence, it remains critical to test the performance of vaccines against challenge with antigenically distinct viruses. We tested the level of protection conferred by an alphavirus-vectored hemagglutinin (HA) subunit vaccine, delivered as a monovalent or bivalent formulation, against challenge with IAV-S. Monovalent alphavirus-vectored HA vaccines provided efficient protection against challenge with viruses with matched and mismatched HA, although in one mismatched HA challenge group there was a trend for reduced protection. A bivalent vaccine, in which two HA’s were simultaneously delivered, was effective in producing antibody response against both antigens and provided protection against challenge. The alphavirus platform is a promising new technology available to swine producers to help reduce the burden of disease caused by IAV-S.