Cell surface CCR5 density determines the postentry efficiency of R5 HIV-1 infection

摘要

We have recently reported that the mean number of CCR5 corecep-tors at the surface of CD4~+ T cells (CCR5 density) correlates with viral load and disease progression in HIV-1-infected persons. Here, we definitively establish that CCR5 density determines the level of virus production and identify the stages of HIV-1 replicative cycle modulated by this effect. We show, by transducing the CCR5 gene into CCR5~+ cells, that CCR5 overexpression resulted in an HIV-1 overin-fectability. We sorted HOS-CD4~+-CCR5~+ cells into two subpopula-tions, HOS~(high) and HOS~(low), the former expressing seven times more cell surface CCR5 molecules than the latter. Virus production was 30-80 times higher in HOS~(high) cells than in HOS~(low) cells after a single round of infection. In contrast, only twice as many viral particles entered the cytosol of HOS~(high) cells as compared with the cytosol of HOS~(low) cells. Yet, seven times as many early, and 24 times as many late, reverse transcription products were found in HOS~(high) cells as compared with HOS~(low) cells. Moreover, a 24- to 30-fold difference in the number of copies of integrated HIV-1 DNA was observed. No difference in HIV-1 LTR activation between the two cell lines was evident. Finally, we show that the higher virus production observed in HOS~(high) cells is inhibited by pertussis toxin, a Gαi protein inhibitor. Thus, CCR5 density mainly modulates postentry steps of the virus life cycle, particularly the reverse transcription. These data explain why CCR5 density influences HIV-1 disease progression and underline the therapeutic interest of lowering CCR5 expression.