Exploring heterologous prime-boost vaccination approaches to enhance influenza control in pigs

Chong Li,Deborah Amodie,Martha A Mellencamp,Marie R Culhane,Maxim Cheeran,Lucina Galina Pantoja,Micah L Jansen,Montserrat Torremorell

doi:10.1186/s13567-020-00810-z

Abstract

Influenza A viruses evolve rapidly to escape host immunity. In swine, this viral evolution has resulted in the emergence of multiple H1 and H3 influenza A virus (IAV) lineages in the United States (US) pig populations. The heterologous prime-boost vaccination strategy is a promising way to deal with diverse IAV infection in multiple animal models. However, whether or not this vaccination strategy is applicable to US swine to impart immunity against infection from North American strains of IAV is still unknown. We performed a vaccination-challenge study to evaluate the protective efficacy of using multivalent inactivated vaccine and/or a live attenuated IAV vaccine (LAIV) in pigs following multiple prime-boost vaccination protocols against a simultaneous H1N1 and H3N2 IAV infection. Our data show that pigs in the heterologous prime-boost vaccination group had more favorable outcomes consistent with a better response against virus challenge than non-vaccinated pigs. Additionally, delivering a multivalent heterologous inactivated vaccine boost to pigs following a single LAIV administration was also beneficial. We concluded the heterologous prime boost vaccination strategy may potentiate responses to suboptimal immunogens and holds the potential applicability to control IAV in the North American swine industry. However, more studies are needed to validate the application of this vaccination approach under field conditions.

Highlights

Influenza A viruses are important zoonotic pathogens and one of the most prevalent causes of respiratory disease
To test whether this vaccination approach is applicable to commercial U.S pig farms, we mimicked field conditions by using a seeder pig infection model where seeder pigs were infected with either an H1 or H3 virus and commingled with the vaccinated pigs to serve as challenge
Our results suggested that the heterologous AUT/COM prime/boost vaccine combination resulted in lower numbers of infected pigs than a whole-cell inactivated vaccines (WIV) homologous prime/boost vaccine combination when compared to NO no vaccination but challenged (VAC/CHA) pigs

Summary

Introduction

Influenza A viruses are important zoonotic pathogens and one of the most prevalent causes of respiratory disease. Its genetic diversity is driven mostly by two mechanisms: antigenic drift which is the result of mutations in antigenic sites due to the poor proofreading ability of the RNA polymerase, and antigenic shift, or reassortment, which is the exchange of gene segments between distinct viruses resulting in new strains with a gene combination distinct from the parental strains. These viral evolution mechanisms are responsible for the emergence of multiple novel distinct H1 and H3 IAV lineages in pigs. The differences of prevailing lineages between different continents and regions require the IAV vaccines for swine to be produced locally and contain distinct strains for each region

Methods

Results

Conclusion