Prevalence of CXCR4 tropism among antiretroviral-treated HIV-1 - Infected patients with detectable viremia

Although CXCR4-tropic viruses are relatively uncommon among untreated human immunodeficiency virus (HIV) infected individuals except during advanced immunodeficiency, the prevalence of CXCR4-tropic viruses among treated patients with detectable viremia is unknown. To address this issue, viral coreceptor usage was measured with a single-cycle recombinant-virus phenotypic entry assay in treatment-naive and treated HIV-infected participants with detectable viremia sampled from 2 clinic-based cohorts. Of 182 treated participants, 75 (41%) harbored dual/ mixed or X4-tropic viruses, compared with 178 (18%) of the 976 treatment-naive participants (P < .001). This difference remained significant after adjustment for CD4(+) T cell count and CCR5 Delta 32 genotype. Enrichment for dual/mixed/X4-tropic viruses among treated participants was largely but incompletely explained by lower pretreatment nadir CD4(+) T cell counts. CCR5 inhibitors may thus be best strategically used before salvage therapy and before significant CD4(+) T cell depletion.