Inactivated Antigen of the H7N9 Influenza Virus Protects Mice from Its Lethal Infection

The H7N9 influenza virus emerged in February 2013 in China, and underlies over 20% of human mortality in the country. Many efforts are being made to develop an effective vaccine against this highly pathogenic virus. We made H7N9 vaccine virus with six internal genes of A/PR/8/34 (H1N1) and two surface genes of hemagglutinin and neuraminidase from A/Anhui/1/2013 (H7N9) by reverse genetics, and the H7N9 vaccine antigens were produced in eggs. Protective antibodies were induced in mice immunized with a single dose (7.5 μg) of the H7N9 antigen. These mice survived lethal infection by the H7N9 virus, although few viruses were found in their lung tissues. However, mice administered with two doses of the H7N9 antigen survived without any viral antigen being detected in their lung tissues. Furthermore, the IgG antibody subtypes were also pronounced in lung tissues of the immunized mice. Therefore, our results suggest that the inactivated whole antigen of the H7N9 influenza virus might protect animals and humans from its lethal infection.