Impairment of human immunodeficiency virus type 1 (HIV-1) entry into Jurkat T cells by constitutive expression of the HIV-1 Vpr protein: Role of CD4 down-modulation

Jurkat T-cell clones, stably expressing the human immunodeficiency virus ty pe 1 (HIV-1) Vpr protein, exhibited an impaired susceptibility to HIV-1 inf ection. A marked down-modulation of surface CD4 receptors was detected in V pr-expressing clones with respect to control cells. Likewise, a reduced CD4 expression was also observed in parental Jurkat cells infected with wild-t ype but not with Vpr-mutant HIV-1. Notably, Vprexpressing clones were fully susceptible to infection with a vesicular stomatitis virus G protein-pseud otyped HIV-1 virus, indicating that a block at the level of viral entry was responsible for the inhibition of viral replication. The effect exerted by Vpr on HIV replication and CD4 expression suggests that this protein can r egulate both the establishment of a productive HIV-1 infection and CD4-medi ated T-cell functions.