MURINE CYTOMEGALOVIRUS REPLICATION IN THE LUNGS OF ATHYMIC BALB C NUDE-MICE/

Murine cytomegalovirus (MCMV) infection in the lungs of T cell-deficie nt athymic BALB/c (Nu/Nu) mice and their immunocompetent heterozygous (Nu/+) littermates was examined. Following intranasal inoculation, MCM V replicated in the lungs of both Nu/Nu and Nu/+ mice, but virus titer s were significantly higher in T cell-deficient mice. After subcutaneo us inoculation, virus disseminated to lung tissue of athymic mice, lea ding to progressive MCMV replication in lungs that was not seen in the immunocompetent mice. Athymic mice failed to develop an antibody resp onse to MCMV. Histologically, athymic mice uniformly developed focal i nterstitial cellular aggregates adjacent to blood vessels or airways, which progressively enlarged and coalesced. Pneumonitis was not seen i n the lungs of any Nu/+ mice. Thus, MCMV can replicate in the lungs wi thout pneumonitis in immunocompetent mice, but MCMV produces a progres sive focal pneumonitis during deficiency of T cell-mediated immunity.