Influence of one virus infection on a second concurrent primary in vivo antiviral cytotoxic T-cell response.

The influence of one virus on the in vivo cytotoxic T-cell response to a different concurrent viral infection was analyzed. Lymphocytic choriomeningitis and Newcastle disease viruses, known to induce high interferon titers, and the synthetic interferon inducer polyriboinosinic acid-polyribocytidylic acid inhibited the cytotoxic T-cell response against the second virus. In contrast, vaccinia and vesicular stomatitis viruses failed to induce inhibition. Inhibition directly correlated with the interferon titers; similarly, the interferon titers directly correlated with macrophage and natural killer cell activation. The involvement in vivo of interferon in macrophage and natural killer cell activation and the possible mechanisms of inhibition of the cytotoxic responses are shown by the inhibition of the effect by antibodies against interferon.