On-site HIV testing was conducted with a protocol using three rapid HIV testing kits: Alere™ Determine™ HIV-1/2 (Alere Medical Co., Ltd., Chiba, Japan), First Response HIV card test 1–2.0 (PMC Medical India Pvt Ltd, Daman, India), and Signal Flow Through HIV 1+2 Spot/Immunodot Test kit, (Span Diagnostics Ltd, Surat, India). Western blot tests were used to characterize samples with indeterminate results with the three rapid kits. In HIV-positive participants, we measured absolute CD4 cell count with the FlowCARE™ PLG CD4 (CD45-FITC/CD4-PE) assay (Beckman Coulter, Brea, CA, USA) and HIV RNA with RealTime HIV-1 assay (Abbott Laboratories, Abbott Park, Illinois, USA).
Among samples from HIV-positive participants, we characterized recent HIV infection according to a multi-assay algorithm that has been validated for HIV subtype C [18 (link)] - the predominant subtype in India [19 (link)]. The algorithm included four assays: CD4 cell count, HIV RNA level, Aware™ BED™ EIA HIV-1 Incidence Test (Calypte Biomedical Corporation, Portland, OR, USA), and an avidity modified GS HIV-1/HIV-2 PLUS O EIA kit (Biorad Laboratories, Redmond, CA, USA) using diethyl amine as the chaotropic agent. HIV-positive subjects were considered recently infected if the CD4 count >200 cells/mm3, HIV RNA >400 copies/mL, BED-CEIA <1.0 normalized optical density, and avidity index <80%.
Among samples from HIV-positive participants, we characterized recent HIV infection according to a multi-assay algorithm that has been validated for HIV subtype C [18 (link)] - the predominant subtype in India [19 (link)]. The algorithm included four assays: CD4 cell count, HIV RNA level, Aware™ BED™ EIA HIV-1 Incidence Test (Calypte Biomedical Corporation, Portland, OR, USA), and an avidity modified GS HIV-1/HIV-2 PLUS O EIA kit (Biorad Laboratories, Redmond, CA, USA) using diethyl amine as the chaotropic agent. HIV-positive subjects were considered recently infected if the CD4 count >200 cells/mm3, HIV RNA >400 copies/mL, BED-CEIA <1.0 normalized optical density, and avidity index <80%.