Role of T lymphocyte subsets in protection and recovery from Hantaan virus infection in mice.

Adult athymic nude (BALB/c background) mice or inbred BALB/c mice were inoculated intraperitoneally with Hantaan virus (HV), and attempts were made to isolate the virus from brain, lung and spleen. Virus was isolated from the organs of BALB/c mice for only a short time after infection but was isolated from various organs of nude mice consistently for at least 84 days after infection. Viral antigen was also detected in various organs of nude mice for a long time after infection. The effects of adoptive transfer of immune serum or immune T cells from BALB/c to nude mice before or after virus inoculation were examined. Before transfer, the T cell fraction was treated with complement (C') (group 1), anti-L3T4 + C' (group 2), anti-Lyt1.2 + C' (group 3) or anti-Lyt2.2 + C' (group 4). When transferred before virus inoculation to test the effects on protection against infection, immune serum and T cells of groups 1, 2 and 4 were effective. When transferred after HV inoculation to test the effects on clearance of virus, group 1 was the most effective followed by group 2. These results suggest that humoral and cellular immunity both have roles in protection against HV infection, and that T cells possessing L3T4- Lyt2+ markers on the cell-surface are especially important for elimination of infectious virus in vivo.