Virus shedding by SV40-transformed human cells

Cultures of human cells transformed by SV40 were found to release infectious virus, even after several passages in vitro. Virus shedding by these cultures did not depend on propagation of virus from cell to cell, as it was not affected by anti-SV40 antiserum that could effectively block virus propagation in acutely infected cells. Cells transformed by the 'early' temperature-sensitive mutant tsA30, and maintained at the restrictive temperature of 39 degrees, shed virus in reduced amount. Finally, xeroderma pigmentosum cells transformed by SV40 were also found to release virus, indicating that the enzymes of excision and repair of UV-induced damage to DNA probably were not involved in the molecular mechanism underlying virus shedding.