Mouse Cytomegalovirus. (Necrosis of Infected and Morphologically Normal Submaxiallary Gland Acinar Cells During Termination of Chronic Infection)

The ultrastructural lesions in the submaxillary glands of C3H mice chronically infected with the murine cytomegalovirus are reported. Virus was synthesized in the nucleus of acinar glandular cells. After passage into the cytoplasm, virus was located in large vesicles which were derived from the Golgi apparatus. These vesicles, which were periodic acid-Schiff positive, migrated to the apex of the cell and released virus into the acinar lumen or canaliculi. Conclusions drawn from electron microscope observations were that lymphocytes terminate chronic MCMV infection, that MCMV infection of acinar epithelium is not cytolytic and that normal cells also undergo necrosis during termination of chronic MCMV infection. It is postulated that lymphocytes in responding to infection release a cytotoxic substance which diffuses into the acini and causes indiscriminate necrosis of acinar cells.