THE ROLE OF SUPERANTIGENS IN VIRUS-INFECTION

Murine mammary tumor viruses are retroviruses which encode superantige ns capable of stimulating T cells via superantigen-reactive T-cell rec eptor V beta chains. Murine mammary tumor viruses are transmitted to t he suckling offspring through the milk. We have established that B cel l-deficient pups which were foster-nursed by virus-secreting mice do n ot transfer infectious murine mammary tumor viruses to their offspring . No murine mammary tumor virus proviruses could be detected in the sp leen and mammary tissue of these mice. We conclude that B cells are es sential for the completion of the viral life cycle in vile. This indic ates that B cells are infected first and that viral amplification take s place only if infected B cells present the murine mammary tumor viru s superantigen on their surface, which, in turn, results in activation of T cells expressing the appropriate T-cell receptor V beta chains. These activated T cells secrete factors which stimulate B cells, enabl ing viral replication.