Title : “ HIV - 1 Vpr induces DNA replication stress in vitro and in vivo ”

The human immunodeficiency virus type 1 (HIV-1) viral protein R (Vpr) causes cell cycle arrest in G2. Vpr-expressing cells display the hallmarks of certain forms of DNA damage, specifically activation of the Ataxia telangiectasiamutated and Rad3-related kinase, ATR. However, evidence that Vpr function is relevant in vivo, or in the context of viral infection is still lacking. In the present study, we demonstrate that HIV-1 infection of primary, human CD4+ lymphocytes causes G2 arrest in a Vpr-dependent manner, and that this response requires ATR, as shown by RNA interference. The event leading to ATR activation in CD4+ lymphocytes is the accumulation of replication protein A (RPA) in nuclear foci, an indication that Vpr likely induces stalling of replication forks. Primary macrophages are refractory to ATR activation by Vpr, a finding that is consistent with the lack of detectable ATR, Rad17 and Chk1 protein expression in these nondividing cells. These observations begin to explain the remarkable resilience of macrophages to HIV-1-induced cytopathicity. To study the in vivo consequences of Vpr function, we isolated CD4+ lymphocytes from HIV-1infected individuals and interrogated the cell cycle status of anti p24 immunoreactive cells. We report that infected cells in vivo display an aberrant cell cycle profile whereby a majority of cells have a 4n DNA content, consistent with the onset of G2 arrest. AC CE PT ED on A uust 0, 2017 by gest http/jvi.asm .rg/ D ow nladed fom Zimmerman et al., page 3