Cross-protective immunity of the hemagglutinin stalk domain presented on the surface of Lactococcus lactis against divergent influenza viruses in mice
Abstract Background Most of the current approaches to influenza vaccine design focus on antibodies against influenza hemagglutinin (HA). However, these influenza vaccines typically provide strain-specific protection against mostly homologous subtypes. There is an urgent need to develop a universal vaccine that confers cross-protection against influenza viruses. Of note, the HA stalk domain (HAs) is a new target for such an influenza vaccine.Results Recombinant L.lactis/pNZ8150-pgsA-HAs constructed in which pgsA was used as an anchor protein and investigated the immunogenicity of HAs, in the mouse model by oral administration without the use of a mucosal adjuvant. Mice were orally vaccinated with L.lactis/pNZ8150-pgsA-HAs, and then produced significant humoral and mucosal immune responses. Importantly, L.lactis/pNZ8150-pgsA-HAs provided significant cross-protection against H5N1, H3N2 or H1N1 virus infection.Conclusions Our data support the hypothesis that HAs presented on the surface of L. lactis can provide cross-protective immunity against influenza A viruses. Taken together, these findings suggest that L.lactis/pNZ8150-pgsA-HAs can be considered an alternative approach to developing a novel universal vaccine during an influenza A pandemic.