The subclass IgG responses of mice to influenza surface proteins formulated into liposomes

Unprimed mice and mice primed by prior infection with an H1N1 subtype of influenza virus were used to assess the total and subclass IgG serum antibody responses to influenza virus A/Sichuan/2/87 (H3N2) surface haemagglutinin and neuraminidase proteins incorporated into four different formulations of liposomes. Only one of these liposome preparations, DSPC(B), induced greater total IgG, and subclass IgG1 and IgG2a antibody levels, in sera from both primed and unprimed mice than the aqueous A/Sichuan surface preparations alone administered at equivalent levels of haemagglutinin protein. The same DSPC(B) liposome formulation of A/Sichuan antigens was also the only preparation found to elicit levels of IgG2b and IgG3 subclass antibodies above baseline values in these animals.