Control of murine cytomegalovirus replication in salivary glands during acute infection is independent of the Fas ligand/Fas system

The course of mouse cytomegalovirus (MCMV) infection was compared between m utant C57BL/6 (B6) mice deficient in either perforin (perf-/-), or perforin , granzyme A and B (perfxcyzmAxB-/-), and B6 gld mice lacking functionally active Fas ligand to elucidate the contribution of the two main cytolytic p athways in the early control of MCMV infection. At 15 and 30 days post infe ction (p.i.) virus titers were elevated in salivary glands of perf-/- and p erfxgzmAxB-/-, but almost undetectable in those of mutant gld and C57BL/6 w ild-type mice. No virus was detectable in lung and spleen tissues of the mu tant or B6 mice at the time points tested. At 15 days p.i., scanty lymphocy tic periductal infiltration was seen in salivary glands of perf-/- and perf xgzmAxB-/; these pathological alterations were minimal at 30 days p.i.. In contrast, no pathological alterations were seen in the respective organs of infected B6 and gld mice at the two time points p.i.. At 15 days p.i., rea ctive follicles were observed in the white pulp of spleen tissues from both mutant and B6 mice, but at 30 days p.i. only in those of mutant mice. No i nflammatory responses were seen in the lung tissues of any of the four mous e strains tested. Together with previous observations (Riera et al., 2000), the results demon strate that both perforin and granzymes A/B, but not the FasL/Fas system ar e critical for viral elimination in salivary glands during the acute phase of infection. However, for the long-term control of MCMV infection, neither of the two cytolytic pathways seem to be necessary.