A permanently growing human endothelial cell line supports productive infection with human cytomegalovirus under conditional cell growth arrest.

Infection of vascular endothelial cells (ECs) is assumed to contribute to dissemination of human cytomegalovirus (HCMV). Investigation of virus-host interactions in ECs such as human umbilical vein endothelial cells (HUVECs) is limited due to the low maximal passage numbers of these primary cells. We tested a conditionally immortalized EC line (HEC-LTT) and a permanent cell line (EA.hy926) for their susceptibility to HCMV infection. Both cell lines resembled HUVECs in that they allowed for entry and immediate early protein expression of highly endotheliotropic HCMV strains but not of poorly endotheliotropic strains, rendering them suitable for analysis of the viral entry mechanism in ECs. The late phase of viral replication and release, however, was supported by growth-controlled HEC-LTT cells but not by EA.hy926 cells. HEC-LTT cells support both the early and late phase of viral replication and release infectious progeny virus at titers comparable to primary HUVECs; thus, the HEC-LTT cell line is a cell culture model representing the full viral replicative cycle of HCMV in ECs. The implementation of permanent HEC-LTT and EA.hy926 cell lines in HCMV research will facilitate long-term approaches that are not feasible in primary HUVECs.