CD4-positive lymphoid cells rescue HIV-1 replication from abortively infected human primary endothelial cells.

Human primary endothelial cell cultures, derived from umbilical vein (HUVEC), can be infected by different strains of HIV-1, but mature virus production remains undetectable both in supernatants and in cellular extracts. Yet viral DNA-is transiently detectable during the first days of infection, but progressively declines during the subsequent days. This finding is characteristic of abortive infections. Co-culture of HUVEC carrying HIV DNA with activated peripheral blood mononuclear cells or with CD 4-positive lymphoid cells elicited a massive cpe (syncytia formation and cell degeneration) in the latter cells, caused by the establishment of productive HIV-1 infection. HUVEC infected in the presence of AZT were significantly impaired in the ability to transmit the infection of CD 4-positive cells, indicating that active DNA synthesis is required in HUVEC before rescue by CD 4-positive cells. These results are of interest in view of the possibility that endothelial cells can play a role in the transmission of HIV-1 infection from infected pregnant women to the foetuses, and, more generally, suggest a potential role of endothelial cells as a transient reservoir of HIV-1.