Vaccination with pertussis toxin alters the antibody response to simultaneous respiratory syncytial virus challenge

Many bacterial toxins, including pertussis toxin (PT), exert potent adjuvant effects on an-tibody synthesis to coadministered antigens. In these studies, we examined whether locally or peripherally administered PT similarly altered the antibody isotype selection to replicating virus after intranasal (inl) challenge. Mice primed intramuscularly with PT and inl with res-piratory syncytial virus (RSV) produced RSV-speci®c antibodies of the IgG2a isotype at a level similar to that of unprimed controls, with some increase in IgG1 production. Mice primed inl with both PT and RSV showed elevated RSV-speci®c IgG1, increased serum IgE levels, and increased interleukin (IL)±4 in lung supernatants. Splenocytes from these animals pro-duced increased IL-4 when stimulated in vitro with RSV or PT antigens after infection. These results suggest that PT can in¯uence the local production of IL-4 to alter the humoral and cellular immune responses to viral infection as well as to coadministered antigens. Vaccines designed to protect against Bordetella pertussis in-fection have been in general use in the United States since the early 1950s, dramatically reducing annual rates of infection and diagnosed cases of whooping cough [1]. Pertussis toxin (PT)