Murine cytomegalovirus replication in the lungs of athymic BALB/c nude mice

Abstract

Murine cytomegalovirus (MCMV) infection in the lungs of T cell-deficent athymic BALB/c (Nu/Nu) mice and thier immunocompetent heterozygous (Nu/+) littermates was examined. Following intranasal inoculation, MCMV replicated in the lungs of both Nu/Nu and Nu/+ mice, but virus titers were significantly higher in T cell- deficient mice. After subcutaneous inoculation, virus disseminated to lung tissue of athymic mice, leading to progressive MCMV replication in lungs that was not seen in the immunocompetent mice. Athymic mice failed to develop an antibody response to MCMV. Histologically, athymic mice uniformly developed focal interstitial cellular aggregates adjacent to blood vessels or airway, which progressively enlarged and coalesced. Pneumonitis was not seen in the lungs of any Nu/+ mice. Thus, MCMV can replied in the lungs without pneumonitis in immunocompetent mice, but MCMV produces a progessive focal pneumonitis during deficiency of T cell-mediated immunity.