Sexual diergism in antibody response to whole virus trivalent inactivated influenza vaccine in outbred mice

An outbred mouse model was used to determine if antibody response to immunization with whole-virus trivalent inactivated influenza vaccine (TIV) differs between the sexes. The antibody response was examined one (serum titer of IgM antibodies), and three and six weeks post-immunization (serum titer of neutralizing and total IgG antibodies and IgG subclass profile). Compared with male in female mice was found (i) the more robust IgM response against all influenza strains included in TIV and (ii) more vigorous neutralizing antibody and total IgG responses against H1N1 influenza virus at both the examined time points post-immunization. The total IgG antibody response against H3N2 and B influenza viruses was comparable between female and male mice three weeks post-immunization, but significantly greater in female mice six weeks post-immunization. The neutralizing antibody response against H3N2 and B influenza viruses did not significantly differ between sexes at both the examined points post-immunization. Finally, three weeks post-immunization subclass profile of IgG specific to the influenza strains included in TIV differed between female and male mice, reflecting the lower titer of IgG1 antibodies in female ones, so that IgG2a (contributing mainly to the total IgG) to IgG1 ratio in mice of this sex was shifted toward the former. In agreement with this shift, compared with male mice, Th1/Th2 balance in female mice was shifted toward Th1, as shown by ELISPOT. Collectively, the results showed influenza virus strain-dependent sexual dimorphism in the magnitude, dynamics and characteristics of antibody response in outbred mice immunized with TIV.