Serum IgG titers elicited by inactivated H1N1 influenza virus antigen. Mice (8 animals/group) were subcutaneously injected at weeks 0 and 3 with 100 μg docetaxel, inactivated H1N1 influenza virus vaccine (equivalent to 10 or 100 ng HA) or inactivated H1N1 influenza virus vaccine (equivalent to 10 ng HA) adjuvanted with docetaxel (25, 50, 100 or 200 μg) or alum (200 μg). Blood samples were collected 2 weeks after the second immunization for analysis of IgG titers by indirect ELISA. Values above the cut-off background level, mean value of sera from saline-immunized mice (negative control) multiplied by a factor of 2.1 were considered positive. Values represent mean ± S.D. Titers were depicted as reciprocal end-dilutions. Significant differences with 10 ng HA groups were designated as *P value < 0.05 and **P < 0.01. N.D. indicates that IgG titer was not detectable at the lowest dilution of serum.