Studies of cell-mediated immunity to Junín virus.

Junín virus is uniformly lethal in newborn mice, but fails to kill adult animals. But there is direct evidence that in older mice the immunological mechanism occurs when certain conditions are fulfilled. The present results showed that in Junín virus infection of mice, the development of the immunological mechanism occurs irrespectively of age. The induction of a regular cell-mediated immunity appears to be intimately related to multiple injections of the virus. These results were confirmed by the 51Cr release assay and by the effect of the transplanted sensitized cells. The extent of infection in the brain is another variable to be considered. Only when the virus has reached high titres and has been concentrated in the brain, the damage done by the immune attack is lethal. On the other hand the data obtained suggest that Junín virus-sensitized spleen cells do not possess the ability to transfer significant antiviral effects to recipient preinfected newborn mice.