Figure 5.

 Titers of hemagglutination inhibition (HI) antibodies against seasonal influenza strains. Mice were immunized with HAB1(H1), HAB1(H3), or HAF1(B) three times, at days 0, 14, and 28, and serum samples were collected prior to each immunization and 2 weeks after the third dose (study day 42). Anti‐A/Brisbane/59/07, A/Brisbane/10/07, and B/Florida/4/06 HI antibody titers were expressed as the reciprocal of the highest dilution of serum that inhibits hemagglutination of eight hemagglutinin units of each virus. Samples without detectable HI antibody titers were assigned a titer of 10. Data shown are the mean titers (log₂) from each group of immunized mice ± SE.