Abstract
Influenza A virus infection is a global health threat to livestock and humans, causing substantial mortality and morbidity. As both pigs and humans are readily infected with influenza viruses of similar subtype, the pig is a robust and appropriate model for investigating swine and human disease. We evaluated the efficacy of the human cold-adapted 2017–2018 quadrivalent seasonal LAIV in pigs against H1N1pdm09 challenge. LAIV immunized animals showed significantly reduced viral load in nasal swabs. There was limited replication of the H1N1 component of the vaccine in the nose, a limited response to H1N1 in the lung lymph nodes and a low H1N1 serum neutralizing titer. In contrast there was better replication of the H3N2 component of the LAIV, accompanied by a stronger response to H3N2 in the tracheobronchial lymph nodes (TBLN). Our data demonstrates that a single administration of human quadrivalent LAIV shows limited replication in the nose and induces detectable responses to the H1N1 and H3N2 components. These data suggest that pigs may be a useful model for assessing LAIV against influenza A viruses.
Highlights
Influenza virus infection is a global health threat to livestock and humans causing substantial mortality
We evaluated the efficacy of human quadrivalent seasonal live attenuated influenza vaccine (LAIV) in pigs against wt H1N1 challenge
Group, accompanied by a strong response to wt H3N2 in the tracheobronchial lymph nodes (TBLN), but we were unable to assess if this was protective, because a separate experiment indicated that wt H3N2 only infects a proportion of pigs
Summary
Influenza virus infection is a global health threat to livestock and humans causing substantial mortality. The traditional intra-muscular inactivated influenza vaccine is only 50–60% effective [2] and induces only strain-specific immunity, requiring repeated annual immunization to match new influenza variants. Potentially more effective, approach is the live attenuated influenza vaccine (LAIV) with absolute efficacy rates of 75–80% in children [3, 4]. Ts mutations inhibit replication of LAIV in the lungs, but these viruses are able to efficiently replicate in the lower temperatures of the nasopharynx. They are administered intra-nasally and induce a wider range of cellular, humoral and mucosal immune responses than the inactivated vaccine [6,7,8]. The major advantage of LAIVs are the greater breadth of protection against antigenic drift variants [9, 10] as well as antigenically-shifted pandemic strains in animal models [11, 12]
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