Infection-permissive immunity provided by conventional influenza vaccination affects host immune responses upon infection and allows induction of heterosubtypic immunity

CHOI A; IBAÑEZ LI; MORALES MINA JA; CHRISTOPOULOU I; SPITAELS J; GARCÍA-SASTRE A; SCHOTSAERT M

Paris

Congreso; Vaccine Congress 2017; 2017

International Society of Vaccines (ISV)

Conventional influenza vaccines aim at the inductionof virus-neutralizing antibodies. However due to antigenic drift or shift ofthe influenza virus, high vaccine efficiencies are not always reported forvaccinees. We investigated to what extent infection-permissive immunity providedby a seasonal trivalent inactivated influenza virus vaccine (TIV) couldmodulate disease and virus-induced host responses after infection with H1N1virus that matches the vaccine. More than one TIV vaccination is needed toinduce high serum HI titers and prevent vast morbidity upon virus infection innaïve mice. However, single TIV administration correlated with lower viral lungtiters and faster recovery after homologous challenge. Contrary to negativecontrol mice, complete abolishment of alveolar macrophages, innate immune cellsthat form the first line of defence against respiratory pathogens, wasprevented in TIV-vaccinated animals. Single TIV vaccination allows theinduction of cross-reactive NPspecific CD8+ T cells by virus infection asdetected in circulation and correlates with protection against subsequentchallenge with heterosubtypic H3N2 virus. When focusing on infection-inducedmucosal immune responses, TIV vaccination does affect levels of pulmonary B andT cell responses after infection. These results suggest that suboptimal vaccinationwith conventional influenza vaccines may still positively modulate disease outcome,thereby allowing induction of heterosubtypic immunity by virus infection.