Mouse splenocyte transfer effect depends on donor's Junin virus infection stage.

Splenocytes from Junin-virus-persistently-infected euthymic mice taken at 45 days postinfection seemed unable to induce overt signs of disease, to cause death, or to modify brain viral levels when transferred to athymic Junin-virus-infected mice. Findings differed sharply when the same recipients were transferred with splenocytes taken at 6 or 30 days postinfection from immunocompetent mice infected in adult life, since mortality reached 80 or 50%, respectively, and brain viral titers were significantly lowered. Furthermore, splenocytes taken at 6 days postinfection from whole adult mice proved harmless to persistently infected euthymic mice. These findings strongly suggest the existence of an immune system alteration in the immunocompetent mouse, attributable to Junin virus persistence. This premise is based on the fact that splenocytes from persistently infected mice were unable to recognize viral antigen expressed on recipient-infected cells. The absence or impairment of a specific cytotoxic T cell population is hereby postulated.