Hemagglutinin stalk immunity reduces influenza virus replication and transmission in ferrets

We assessed in ferrets whether influenza virus hemagglutinin stalk-based immunity provided protection against aerosol-transmitted H1N1 infection. Immunization of ferrets with a universal influenza virus vaccine strategy based on viral vectors expressing chimeric hemagglutinin constructs induced stalk-specific antibody responses. Stalk-immunized ferrets were co-housed with H1N1-infected ferrets under conditions that permitted virus transmission. Hemagglutinin stalk-immunized ferrets had lower viral titers, delayed or no virus replication at all following natural exposure to influenza virus.