Natural killer cells appear to play no role in the recovery of mice from Sindbis virus infection.

Previous studies have suggested that non-specific defence mechanisms may be important in the development of age-dependent resistance to fatal Sindbis-virus infection and in the recovery of adult mice from non-fatal infection. In these studies, natural killer (NK) cell induction was studied in 7-day-old susceptible mice and 28-35-day-old resistant mice. It was found that Sindbis virus infection induced NK cells in both the young and older mice, suggesting that NK cells were not important in the acquisition of resistance to fatal Sindbis-virus infection. Transfer of 10(8) lymph node cells from adult, mice, at the peak of NK cell activity, did not protect young mice from fatal infections, supporting the in vitro findings. The pathogenesis of Sindbis virus infection in C57BL/6J bg/bg (NK-cell deficient) and bg/+ (NK-cell normal) mice was also studied. Despite a defect in the induction of NK cells by Sindbis virus infection in the bg/bg mice, there were no significant differences in the pathogenesis of either peripheral or intracerebral infection in these strains of mice. These studies suggest that although NK cells are induced, they may not be important in the recovery of mice from Sindbis virus infection.