PRODUCTIVE REPLICATION OF HUMAN CYTOMEGALOVIRUS IN PRIMARY MICROGLIALCELL-CULTURES

Human cytomegalovirus (HCMV) infection can result in neurological symp toms. In vitro replication of the HCMV was studied in primary cultures of microglial cells from the central nervous systems (CNS) of human e mbryos, The microglial cells were infected with various amounts of eit her the AD169 laboratory HCMV strain or a clinical HCMV isolate. A spe cific cytopathic effect occurred within 24 h and persisted for two mon ths. Immunocytochemical tests for immediate early and late viral antig ens done one and three days after the infection demonstrated that 60% to 80% of the microglial cells were infected and that 3% to 8% were th e site of viral DNA replication. Kinetic studies showed accumulation o f viral particles in the supernatant during the first two weeks after the infection. Prestimulation of the cells by PMA 24 h before the infe ction was associated with increased release of viral particles and wit h an increased percentage of cells expressing late viral antigens, The microglial cells of the human embryonic CNS are fully permissive targ ets for the HCMV. The in vitro HCMV model used in this study may prove useful for investigating the pathophysiology of HCMV encephalitis, in particular after mother-to-fetus transmission of the virus.