Human Cytomegalovirus Infection Inhibits the Differentiation of Human Hippocampus Neural Precursor Cells into Astrocytes

HCMV is a major cause of congenital brain disease in humans, and its neuropathogenesis is not yet fully understood. The objective of the present study is to investigate the effect of human cytomegalovirus （HCMV） infection on human hippocampus neural precursor cell （NPCs） differentiation in vitro. Fetal hippocampus tissue was dissociated mechanically and then cultured in proliferation medium with EGF and bFGF. The identification and purity of the NPCs were confirmed by using immunofluorescence to detect the expression of the NPCs marker-Nestin. To drive NPCs differentiation, bFGF and EGF were withdrawn from the medium and replaced with FBS （10%）. HCMV AD169 （MOI=5） was added into the differentiation medium at the onset of the differentiation. After 7 days of differentiation, in order to confirm whether NPCs are permissive for HCMV infection, immunofluorescence was used to stain for the presence of immediate early （IE） and late （pp65） HCMV proteins in the infected cells. The effects of HCMV infection on NPCs＇ differentiation was observed by detecting the ratio of nestin and GFAP positive cells with confocal microscopy and immunofluorescence. The data showed that 95%±8% of the cells （passage 4-8） cultured were Nestin positive which suggested that majority of the cells were NPCs. On day 7 postinfection, most of the infected cells were IE and PP65 positive. The percentage of Nestin-positive cells were 93%±10% and 50%±19% （t=6.03, p〈0.01） and those of GFAP-positive cells were 55±17% and 81%±11% （t=3.77, p〈0.01） in HCMV treated and control groups respectively. These findings indicate that NPCs are HCMV permissive cells and HCMV （AD 169） infection suppresses the differentiation of Hippocampus-genetic human NPCs into astrocytes. These effects may provide part of the explanation for the abnormalities in brain development associated with congenital HCMV infection.