To determine the effect of cholera toxin as a mucosal adjuvant on the class and subclass antibody response to RSV, mice were immunized intranasally with different doses of live RSV or UV-inactivated RSV mixed with cholera toxin. A single 10(6) pfu dose of live RSV and a single 50 micrograms dose of UV-inactivated RSV mixed with cholera toxin produced comparable serum IgG and respiratory secretion IgG and IgA antibody titers. Subclass antibody titers to whole RSV were also comparable between these two immunizing regimens. A predominance of IgG2a subclass to whole RSV was found for both regimens. The quantity of serum total IgG antibody to glycoprotein F or glycoprotein G did not differ between these regimens. The serum IgG subclass antibody response to both glycoprotein F and G was also not significantly different between regimens. Cholera toxin as a mucosal adjuvant can stimulate class and subclass antibody responses to UV-inactivated RSV that are similar in quantity and distribution to those after live RSV infection.