Inclusion of flagellin increases antibody responses in nonhuman primate neonates following influenza vaccination (VAC8P.1002)

Abstract Influenza virus can cause life-threatening infections in neonates and young infants. Although vaccination is a major countermeasure against influenza, current vaccines are not approved for use in infants less than 6 months of age, in part due to the weak immune response to vaccination. Thus, there is a strong need to develop new vaccines with improved efficacy for use in this vulnerable population. To address this issue we developed an African Green Monkey model that could be used to identify effective influenza vaccine approaches for use in young infants. We assessed the ability of flagellin, a TLR5 agonist, to serve as an effective adjuvant for vaccination of neonates. Animals were primed and boosted with inactivated PR8 influenza virus in the presence of either flagellin or an inactive form of the protein. Inclusion of flagellin significantly increased the level of influenza-specific serum IgG present following boosting as well as at early times after virus challenge. Animals receiving flagellin adjuvanted vaccination also exhibited higher levels of respiratory influenza-specific IgG at early times post challenge. Interestingly, there was no flagellin mediated increase in IgM. The presence of flagellin also resulted in an increase in neutralizing antibody. This study supports further exploration of flagellin as an effective adjuvant for inducing vaccine responses against influenza in neonates.