The cytotoxic response to murine cytomegalovirus. I. Parameters in vivo.

Combined in vivo and in vitro protocols for the generation of anti-murine cytomegalovirus (anti-MCMV) cytotoxic responses were investigated using BALB/c mice and syngeneic mouse embryo fibroblast target cells. Injections of doses of MCMV from 10(2.6) up to 10(6.1) p.f.u. into the hind footpad, harvest of draining popliteal lymph node cells after 6 to 8 days, followed by 4 days culture of these cells gave similar and optimal cytotoxic activity against MCMV-infected target cells. After injection of 10(4.6) p.f.u. into the hind footpad, MCMV was detectable at about 10(3) to 10(4) p.f.u. per popliteal node after 3 days, but became undetectable in most animals by 6 days. Cell numbers in the draining popliteal lymph node increased following MCMV inoculation into the hind footpad, but the extent of the increase was inversely related to virus dose and bore no relationship to the anti-MCMV cytotoxic potential of the cells. Lymph node cells applied directly to target cells upon harvest from MCMV-infected mice never gave detectable anti-MCMV cytotoxic activity at 2, 4, 6, 8, 10, 12, 17 or 19 days post-infection, but lysis of uninfected syngeneic targets was obtained 4 to 8 days post-infection.