Cytomegalovirus infection of murine testicular interstitial Leydig cells.

We studied the susceptibility of mouse testicular interstitial Leydig cells to cytomegalovirus both in vivo and in vitro. The in vivo studies included intratesticular and intraperitoneal infection of 6-week-old mice with murine cytomegalovirus (MCMV); the in vitro studies involved an MCMV-Leydig cell interaction using a Leydig tumor cell line (I-10). MCMV-specific antigens were detected in interstitial Leydig cells in sections of MCMV-inoculated testes by an indirect immunofluorescence test. MCMV DNA was also localized in the same testes cells derived from mice, which received intratesticular and intraperitoneal MCMV inoculations, respectively, by in situ DNA-RNA hybridization. Cytopathic effects were seen in MCMV-infected I-10 cell cultures 2 or more days after exposure to MCMV. The infected cells showed intranuclear inclusions characteristic of cytomegalovirus when stained with May-Grunwald-Giemsa stain. The indirect immunofluorescence test was also positive with MCMV-infected I-10 cells. MCMV DNA was detected in these cells by in situ DNA-RNA cytohybridization, and the presence of viral particles in MCMV-infected I-10 cells was confirmed by electron microscopy. Thus, we conclude that the interstitial Leydig cell is susceptible to MCMV infection both in vivo and in vitro.