Viremia and glial nodule encephalitis after experimental systemic cytomegalovirus infection.

Despite the importance of cytomegalovirus (CMV) infection of the central nervous system in acquired immune deficiency syndrome, a well characterized laboratory model of glial nodule encephalitis after systemic CMV infection is not available. We now report that after intraperitoneal infection of young guinea pigs with CMV, infection of the brain was routinely found in the 2nd week. Recovery of virus from the brain was achieved at the time of viremia. Histopathologic changes in the brain followed the recovery of virus and continued beyond the point that virus was cleared from the brain. Microglial nodules, which were sometimes observed in association with intranuclear inclusion bearing cells, were the predominant feature. Other histopathology included perivascular infiltrates, vascular endothelial swelling, subependymal infiltrates, and sporadic focal leptomeningitis. In comparison to our previous studies after intracerebral inoculation, parenchymal changes dominated and leptomeningitis was found infrequently. The present studies suggest that focal central nervous system infection by CMV may be relatively common, though clinically silent, in the course of systemic infection. Relevant to acquired immune deficiency syndrome, the model should facilitate studies of the mechanism of brain infection, local central nervous system host defense, and mechanisms of injury to the brain.