Different roles for cytotoxic T cells in the control of infections with cytopathic versus noncytopathic viruses.

The assessment of the role of T-cell-mediated cytotoxicity in immunity to viral infections has been difficult to address directly and therefore has been controversial. Recent experiments with perforin-deficient mice have shown that cytotoxicity is crucial for the resolution of infection with lymphocytic choriomeningitis virus but not for the resolution of infection with vaccinia, vesicular stomatitis, Semliki Forest or influenza virus. These findings may reflect the general pattern that T-cell-mediated cytotoxicity is crucial only for the resolution of infections with noncytopathic viruses, whereas infections with cytopathic viruses are mainly controlled by soluble mediators such as antibodies and interferons.