1659 MURINE CYTOMEGALOVIRUS INFECTION OP FETAL BRAIN AGGREGATES

Abstract

Human cytomegalovirus (CMV) infection can severely damage the developing nervous system and cause major neuropathologic abnormalities including cerebral necrosis, cerebral calcification and defects in neuronal migration. To study CMV infection of developing neural tissues, we infected fetal mouse brain cell cultures in vitro with the Smith strain of murine CMV (MCMV). Aggregating brain cell cultures were prepared from late-term fetal mice and after 21 to 28 days in culture were inoculated with 1.0 plaque-forming unit (pfu) of MCMV per 103 viable cells. MCMV could be recovered from culture fluids 1, 3, 5, 7 and 14 days after infection, and titers of MCMV rose steadily: mean of 4.0 pfu of MCMV/ml of culture fluid on day 1, 6.7 × 101 pfu of MCMV/ml on day 3, 4.3 × 103 pfu of MCMV/ml on day 5 and 7.6 × 103 pfu of MCMV/ml on day 7. Assay of washed brain aggregates 7 days after infection yielded 4.6 × 102 pfu of MCMV per aggregate, and immunofluorescence staining confirmed the presence of MCMV antigens. Electron microscopic studies of MCMV-infected aggregates demonstrated intranuclear inclusions and numerous intranuclear and intracytoplasmic virus particles in neurons, astrocytes and oligodendrocytes. These results indicate that MCMV replicates in fetal mouse brain aggregates and produces ultrastructural changes typical of CMV infections. These studies provide an in vitro method by which to investigate the effects of CMV infection on developing neural tissues.