Role of T lymphocytes in recovery from murine cytomegalovirus infection.

Congenitally athymic nude (Nu/Nu) mice inoculated intraperitoneally with murine cytomegalovirus (MCMV), in doses as low as 1.3 X 10(1) plaque-forming units succumbed to the infection. In contrast, the mean lethal dose for heteroxygous euthymic (Nu/+) littermates was 4 X 10(3) plaque-forming units. Though histopathological changes consistent with MCMV infection were found in the spleen, lungs, and adrenals of nude mice, there were only small focal areas of involvement in the liver. In contrast, Nu/+ mice dying from infection had pathological evidence of severe hepatitis. Spleen cells from immune and control BALB/c mice were injected intravenously into syngeneic mice that had been inoculated previously with lethal doses of MCMV intraperitoneally. Mice receiving 1 X 10(7) or more immune spleen cells were protected against the infection, whereas mice receiving 1 X 10(8) control spleen cells or immune serum were not. Treatment of immune spleen cells with anti-theta serum and complement significantly reduced their protective effect. Immune mechanisms associated with T lymphocytes appear to be critical for recovery from MCMV infection.