Cell-free versus cell-to-cell infection by HIV-1 and HTLV-1: exploring the link among viral source, viral trafficking and viral replication.

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Dutartre H, Clavière M, Journo C, Mahieux R,

Dutartre H, Clavière M, Journo C, Mahieux R, (click to view)

Dutartre H, Clavière M, Journo C, Mahieux R,


Journal of virology 2016 6 22() pii


HIV-1 and HTLV-1 are complex retroviruses mainly infecting CD4(+) T lymphocytes. In addition, antigen-presenting cells such as dendritic cells (DCs) are targeted in vivo by both viruses, although to a lesser extend. Interaction of HIV-1 with DCs plays a key role in viral dissemination from the mucosa to CD4(+) T lymphocytes present in lymphoid organs. While similar mechanisms may occur for HTLV-1 as well, most HTLV-1 data were obtained from T-cell studies, and little is known regarding the trafficking of this virus in DCs. We first compared the efficiency of cell-free versus cell-associated viral sources of both retroviruses at infecting DCs. We showed that both HIV-1 and HTLV-1 cell-free particles are poorly efficient at productively infecting DCs, except if DC-SIGN has been engaged. Furthermore, while SAMHD1 accounts for restriction of cell-free HIV-1 infection, it is not involved in HTLV-1 restriction. In addition, cell-free viruses mainly lead to a non-productive DC infection leading to trans-infection of T-cell a process important for HIV-1 spread but not for that of HTLV-1. Finally, we show that T:DC cell-to-cell transfer implies viral trafficking in vesicles that may both increase productive infection of DCs ("cis-infection") and allow viral escape from immune surveillance. Altogether, these observations allowed us to draw a model on HTLV-1 and HIV-1 trafficking in DCs.

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