HA-specific serum antibody response.

<p>H5 HA-specific serum antibody response of mice elicited after i.m. immunization with 10⁷ pfu of D1701-V-HAh5n. The hemagglutination inhibition (HI) titers (reciprocal log2) of individual mice were determined 1 week after prime immunization (V1), after booster immunization (V2), and at the day of challenge infection (Ch). Sera from control mice immunized twice with 10⁷ pfu of D1701-VrV (VrV) displayed unspecific HI titers of 1∶16. The lines denote the mean titers calculated from the individual sera.