Human endothelial cells isolated from the hepatic sinusoids and the umbilical vein display a different permissiveness for HIV1.

Endothelial cells are now considered as potential targets for HIV infection, together with other non-lymphoid cells. We previously demonstrated that endothelial cells isolated from the human liver sinusoids (SEC) are permissive for HIV1 in vitro (Steffan et al., 1992), whereas human umbilical vein endothelial cells (HUVEC) do not allow replication of seven HIV1 and HIV2 strains under the same infection conditions (Lafon et al., 1992). The aim of our work was to compare the permissiveness of SEC and HUVEC and to determine whether the lack of HIV replication in HUVEC, which do not possess CD4 receptors (Lafon et al., 1992), could be related to the absence of virus penetration. The bypass of the early events in the virus life cycle, including the stage of fusion, by transfection of HUVEC with the HTLV-IIIB provirus led to one cycle of viral replication. Moreover, a low level of viral replication was observed in HUVEC infected with the NDK HIV strain, known to penetrate its target cell in a CD4-independent fashion. These results indicate that the block of infection in HUVEC takes place during the early stages of the viral replicative cycle. However, given the low level of NDK replication in HUVEC (0.02% infected cells) in comparison with NDK-infected SEC (30 to 50% infected cells), the absence of the CD4 receptor on HUVEC may not be the only limiting factor for viral growth. Although these two types of endothelial cells display a very different permissiveness for HIV, the present data suggest that they could both serve as a viral reservoir.