Evaluation of a rapid antigen and antibody combination test in acute HIV infection

Background: New strategies at implementing HIV testing including rapid HIV assays are highly recommended to avoid late diagnosis. To shorten the diagnostic window period, the first point-of-care HIV assay, Determine HIV 1/2 Ag/Ab Combo (D4G, Alere, I) for the combined detection of p24 and anti-HIV antibody has been recently marketed and mainly tested in high prevalence setting. Objectives: To establish D4G performances in acute HIV infection (AHI) in a setting at low HIV-1 prevalence. Study design: D4G performances were compared with HIV-1 RNA levels in a panel of well-characterized serum specimens from 17 patients with AHI. For specificity, 124 anti-HIV negative serum specimens from patients seeking HIV testing were studied. Results: D4G detected HIV infection in 15/17 patients. D4G antigen was positive in only 5 patients (29.4%), 4 of them with a viral load >10 million copies/mL. D4G antibody was reactive in other 10 patients (sensitivity: 58.8%, viral load from 70,161 to 8,120,000 copies/mL). Combined D4G sensitivity for acute HIV-1 infection was 88.2%; no false positive or invalid result was recorded (100% specificity, positive and negative predictive values: 100% and 98.4%, respectively). Conclusion: In spite of a poor antigen sensitivity with optimal performances only for viral load >10 million copies/mL, D4G performances in acute HIV-1 infection were enhanced by the addition of p24 testing to the antibody. Improved HIV rapid testing to shorten the window period is important as rapid tests play a major role in expanding access to HIV testing and preventing HIV transmission. (C) 2013 Elsevier B. V. All rights reserved.