CD8(-CELLS CAN MEDIATE ALMOST COMPLETE SHORT-TERM AND PARTIAL LONG-TERM IMMUNITY TO ROTAVIRUS IN MICE() T)

We have recently shown that CD8(+) T cells mediate clearance of rotavi rus infection in mice, B-cell-deficient J(H)D knockout (-/-) mice depl eted of CD8(+) T cells become chronically infected with murine rotavir us, and beta(2) microglobulin -/- and other mice depleted of CD8(+) T cells have a 1- to 4-day delay in clearance of primary rotavirus infec tion. A role for CD8(+) T cells in protection from reinfection with ro tavirus was suggested by these studies, because J(H)D -/- mice rechall enged 6 to 8 weeks after primary infection shed smaller quantities of viral antigen and for fewer days than naive mice, Here we show that 8, 11, 13, and 18 days after primary infection the J(H)D -/- mice are al most completely resistant to reinfection and that they are still parti ally protected from reinfection 6 weeks, 5 months, and 8 months after primary infection, Protection against reinfection was dependent on CD8 (+) T cells, since J(H)D -/- mice depleted of CD8(+) T cells by admini stration of an anti-CD8 monoclonal antibody became chronically infecte d with rotavirus upon rechallenge 13 days, 18 days, 6 weeks, and 5 mon ths after primary infection, Thus, CD8(+) T cells can actively mediate almost complete short-term and partial long-term protection from rein fection.