Performance of Galectin-9 for Identification of HIV Viremia in Adults Receiving Antiretroviral Therapy in a Resource-Limited Setting

Background: Targeted viral load (VL) testing has been proposed for antiretroviral treatment (ART) monitoring in resource-limited settings. In this study, we have investigated the performance of the host biomarker galectin-9 (Gal-9), alone and in combination with interferon-γ-inducible protein 10 (IP-10), in identifying individuals at increased likelihood of viremia during ART.Setting:Cohort of HIV-positive adults receiving ART at Ethiopian health centers.Methods:We included participants with detectable viremia (VL ≥150 copies/mL) 12 months after starting ART and sex-matched nonviremic controls. Performance to identify individuals with VL ≥1000 copies/mL was determined for Gal-9 and the Gal-9/IP-10 combination, respectively, using receiver operating characteristic (ROC) analysis.Results:Among 191 participants (50.3% women), 46 (24.1%) had VL ≥1000 copies/mL, 23 (12.0%) had 150-999 copies/mL, and 122 (63.9%) had <150 copies/mL. Gal-9 and VL were positively correlated (rs= 0.451, P < 0.001). Sensitivity and specificity for Gal-9 to identify individuals with VL ≥1000 copies/mL were 91.3% (95% CI: 79.2-97.6) and 54.5% (95% CI: 46.0-62.8), respectively. The area under the ROC curve for Gal-9 was 0.810 (95% CI: 0.745-0.875), which was similar to that of the combination of Gal-9 and IP-10 [0.849 (95% CI: 0.792-0.905)]. Assuming 10% prevalence of VL ≥1000 copies/mL, using Gal-9 for targeted VL testing instead of universal VL testing would reduce the number of VL tests from 10 to 5 to identify 1 viremic individual, with misclassification of 1 in 10 viremic individuals.Conclusions:Gal-9 is a potential screening marker for targeted VL monitoring in ART recipients. Further studies are needed to determine optimal threshold levels