Journal of clinical microbiology 2017 05 17() pii 10.1128/JCM.00235-17
HIV plasma viral load is an established marker of disease progression and of response to antiretroviral therapy but currently there is no commercial assay validated for the quantification of viral load in HIV-2 infected individuals. The aim of this study was to make the first clinical evaluation of Cavidi ExaVir™ Load version 3 in HIV-2 infected patients. Samples were collected from a total of 102 individuals living in Cape Verde and HIV-2 viral load was quantified by both ExaVir™ Load and a reference in-house real-time quantitative PCR (qPCR) used in Portugal in 91 samples. The association between viral load and clinical prognostic variables (CD4(+) T cell counts and antiretroviral therapy status) was similar for measurements obtained with ExaVir™ Load and qPCR. There was no difference between both methods in the capacity to discriminate between non-quantifiable and quantifiable HIV-2 in the plasma. In samples with quantifiable HIV-2 viral load by both methods (n=27), the measurements were highly correlated (Pearson r=0.908) but ExaVir™ Load values were systematically higher relative to qPCR (median difference 0.942 log10 copies/ml). A regression model was derived that enables the conversion of the ExaVir™ Load results to those that would have been obtained by the reference qPCR. In conclusion, ExaVir™ Load version 3 is a reliable commercial assay to measure viral load on HIV-2 infected patients and, therefore, a valuable alternative to the in-house assays in current use.