Fate of interferon-treated cells.

Interferon-treated cultures of Ly cells survived initial infection with high multiplicities of vesicular stomatitis (VSV) or herpes simplex virus (HSV). In the case of HSV, infectious virus and intracellular viral antigen were rapidly eliminated from the interferon-treated cultures, and the cells grew out to form apparently normal monolayers that could be cultured indefinitely. In the VSV-infected Ly cultures, virus titers remained at low levels in interferon-treated cells but after about 14 days rapidly rose and the culture was destroyed. If interferon was added to the medium on days 4 and 6 after infection, virus titers rapidly declined but again recovered and the cells were destroyed. If, however, interferon treatment was resumed 9 days after initial infection, detectable infectious VSV was eliminated from the medium. Several methods, including cocultivation and molecular hybridization, failed to demonstrate persistence of a significant portion of the VSV genome in these cultures.