van Santen DK, et al. - Researchers investigated the effect of incident hepatitis C virus (HCV) infection, and its timing relative to HIV seroconversion (HIVsc) in HIV-positive MSM on their subsequent CD4+ T-cell count and HIV RNA viral load trajectories. From 17 cohorts, MSM with well-estimated dates of HIVsc were included within the CASCADE Collaboration. They matched 214 (antiretroviral therapy-naive) and 147 [on combination antiretroviral therapy (cART)] HCV-coinfected MSM to 5384 and 3954, respectively, matched HIV monoinfected MSM. Temporary lowering of CD4+ cell counts following HCVsc was noted irrespective of the duration of HIV infection when HCV is acquired, even when on cART. During the first 2 years after HCVsc, ART-naive MSM displayed HIV RNA viral load levels lower or comparable with HIV monoinfected; these loads tend to increase thereafter. In MSM on cART, a detectable HIV RNA viral load was not influenced by HCV.