Pulmonary T cells induced by respiratory syncytial virus are functional and can make an important contribution to long-lived protective immunity.

The contribution of T cell responses to immunity against respiratory syncytial virus (RSV) is not fully defined, but this is an important issue for vaccine design. Recent studies demonstrating RSV-induced pulmonary T cell suppression suggest that RSV may have evolved strategies to escape T cell immunity. Here we evaluated potential consequences of RSV-mediated immunosuppression for protective memory T cell responses in vivo. Surprisingly, we found strong ex vivo cytolytic activity and interferon production of pulmonary RSV-specific CD8(+) T cells both in the acute and the memory phase of primary murine RSV infection. More significantly, T cell memory made an important contribution to immunity against RSV independent of antibodies. Thus, RSV-primed mice were protected against challenge with RSV-recombinant vaccinia viruses, which can be controlled by RSV-specific T cells, but not by RSV-specific antibodies. In conclusion, RSV does not appear to impair acute and protective memory T cell responses induced by a primary infection. These findings further support that induction of T cell immunity should be a relevant goal for RSV vaccines.