Contribution of T cells to mortality in neurovirulent Sindbis virus encephalomyelitis.

Intranasal inoculation of C57BL/6 mice with a neurovirulent strain of Sindbis virus (SV) results in fatal encephalomyelitis. Mice with selective immune deficiencies were studied to determine the role of the immune response in fatal outcome. Mortality was decreased in mice deficient in alphabeta, but not gammadelta, T cells demonstrating a contribution of alphabeta T cells. Mice lacking either CD4+ or CD8+ T cells also had reduced mortality and mice lacking interferon (IFN)-gamma were completely protected. Clearance of infectious virus was identical in mice without T cells or IFN-gamma, but clearance of viral RNA was delayed compared to normal mice. Mice unable to produce antibody, perforin, Fas, TNF-alpha receptor1, IL-6 or IL-12 were not protected. These data suggest that T cells contribute to fatal acute viral encephalomyelitis through the production of IFN-gamma.