Quantitation of human immunodeficiency virus type 1 viral load in plasma using reverse transcriptase activity assay at a district hospital laboratory in Botswana: a decentralization pilot study.

Roche COBAS Amplicor monitor version 1.5 assay is considered gold standard for viral load monitoring in Botswana. Due to its demand for elaborate infrastructure, viral load testing has been confined to the national HIV reference laboratories. Cavidi ExaVir Load version 2 assay was considered as a potential alternative to decentralize viral load testing to the rural/remote hospital laboratories and thus increase access to therapy. This study compared the performance of ExaVir Load v2 assay at a district hospital laboratory in Serowe and COBAS Amplicor monitor v1.5 assay at the Botswana Harvard HIV Reference Laboratory using quality assessment samples and plasma from HIV-positive individuals. ExaVir Load v2 and COBAS Amplicor monitor v1.5 assays had very good agreement; Kappa statistic 0.951. The COBAS Amplicor monitor v1.5 and ExaVir Load v2 assays detected HIV-1 RNA in 84 and 86 samples but did not detect HIV-1 RNA in 221 and 219 samples, respectively. The two assays detected HIV-1 RNA concordantly in 82 samples and were strongly correlated (r=0.8554, P<0.0001). ExaVir Load v2 assay provided a simple and reliable alternative viral load system that is adaptable to district hospital laboratories. The cost per test is less than RT-PCR. The ExaVir Load v2 systems have since been placed in four more district and primary hospital laboratories.

HIV-1 subtype C in vitro growth and coreceptor utilization.

Human immunodeficiency virus type 1 subtype C (HIV-1C) accounts for about 50% of all HIV infections in the pandemic and is the predominant subtype in the heavily burdened region of southern Africa. HIV-1C possesses unique genetic and phenotypic features that might be associated with biological differences compared to other subtypes. Here, we generated virus isolates from individuals at different stages of HIV-1C infection and investigated the chemokine receptor repertoire that the derived HIV-1C isolates may utilize for entry. Our results show that the R5 phenotype predominates among viruses in Botswana, with a lesser contribution of viruses showing the dualtropic X4R5 phenotype. No viruses of pure X4 phenotype were found, which suggests no discernable evolution of HIV-1C to a monotropic X4 phenotype as the epidemic ages in Botswana. Usage of other coreceptors was rare and apparently insignificant. These results enhance our understanding of HIV-1C biology, with implications for designing and testing therapeutic and prophylactic agents.