Later Passages of Neural Progenitor Cells from Neonatal Brain Are More Permissive for Human Cytomegalovirus Infection

Congenital human cytomegalovirus (HCMV) infection is the most frequent infectious cause of birth defects, primarily neurolog-ical disorders. Neural progenitor/stem cells (NPCs) are the major cell type in the subventricular zone and are susceptible to HCMV infection. In culture, the differentiation status of NPCsmay change with passage, which in turnmay alter susceptibility to virus infection. Previously, only early-passage (i.e., prior to passage 9) NPCs were studied and shown to be permissive to HCMV infection. In this study, NPC cultures derived at different gestational ages were evaluated after short (passages 3 to 6) and extended (passages 11 to 20) in vitro passages for biological and virological parameters (i.e., cell morphology, expression of NPC markers and HCMV receptors, viral entry efficiency, viral gene expression, virus-induced cytopathic effect, and release of infec-tious progeny). These parameters were not significantly influenced by the gestational age of the source tissues. However, extend-ed-passage cultures showed evidence of initiation of differentiation, increased viral entry, andmore efficient production of infec-tious progeny. These results confirm that NPCs are fully permissive for HCMV infection and that extended-passage NPCs initiate differentiation and are more permissive for HCMV infection. Later-passage NPCs being differentiated andmore permis-sive for HCMV infection suggest that HCMV infection in fetal brain may cause more neural cell loss and give rise to severe neu