Cytotoxic T lymphocytes and natural killer cell activity in the course of mengo virus infection of mice

Inbred C57BL/6 mice were inoculated intraperitoneally (i.p.) with mengo virus. The activity of cytotoxic T lymphocytes (CTL) and natural killer (NK) cells were measured during the first 22 days following injection. The CTL response began 7 days after virus inoculation, persisted for at least 22 days and was related to the dose of the virus inoculated. NK cell activity was elevated within 24 hr, reached its peak level on the fourth day and declined to normal levels on the eleventh day after exposure to the virus. These results suggest that NK cells represent the first cellular immune response to restrict mengo virus spread while specific CTL appear later and are probably responsible for further restriction, elimination and prevention of the viral disease.