Research Article
Antibody Response to Influenza Hemagglutinin Conserved Stalk Domain after Sequential Immunization with Old Vaccine Strains
Figure 5
Plaque plates showing plaque-reduction neutralizing activity of sera from unimmunized control mice and immunized mice in homologous and heterologous groups. Plaque reduction was comparable in all groups, indicating the absence of neutralizing antibody against the HA stalk.