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

Many bacterial toxins, including pertussis toxin (PT), exert potent adjuvan t effects on antibody synthesis to coadministered antigens. In these studie s, we examined whether locally or peripherally administered PT similarly al tered the antibody isotype selection to replicating virus after intranasal (inl) challenge. Mice primed intramuscularly with PT and inl with respirato ry syncytial virus (RSV) produced RSV-specific antibodies of the IgG2a isot ype 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-s pecific IgG1, increased serum IgE levels, and increased interleukin (IL)-4 in lung supernatants. Splenocytes from these animals produced increased IL- 4 when stimulated in vitro with RSV or PT antigens after infection. These r esults suggest that PT can influence the local production of IL-4 to alter the humoral and cellular immune responses to viral infection as well as to coadministered antigens.