Lactococcus lactis displayed neuraminidase confers cross protective immunity against influenza A viruses in mice.

Influenza A viruses pose a serious threat to public health. Current influenza A vaccines predominantly focus on hemagglutinin (HA) and show strain-specific protection. Neuraminidase (NA) is much less studied in the context of humoral immunity against influenza A viruses. The purpose of this study is to evaluate the cross protective immunity of NA presented on Lactococcus lactis (L.lactis) surface against homologous and heterologous influenza A viruses in the mouse model. L.lactis/pNZ8110-pgsA-NA was constructed in which pgsA was used as an anchor protein. Mice vaccinated orally with L.lactis/pNZ8110-pgsA-NA could elicit significant NA-specific serum IgG and mucosa IgA antibodies, as well as neuraminidase inhibition (NI) titers. Importantly, L.lactis/pNZ8110-pgsA-NA provided 80% protection against H5N1, 60% protection against H3N2 and H1N1, respectively. These findings suggest that recombinant L.lactis/pNZ110-pgsA-NA in the absence of adjuvant via oral administration can be served as an effective vaccine candidate against diverse strains of influenza A viruses.