Evaluation of a 4th generation rapid HIV test for earlier and reliable detection of HIV infection in pregnancy

Background Currently used 3rd generation rapid HIV-tests in resource-limited settings do not detect acute HIV-infections (AHI). They are known to detect HIV-infections after or late in the "window period". Detecting incident-HIV infections early in pregnancy increases opportunities for initiating antiretroviral prophylaxis to prevent mother-to-child transmission of HIV. Objectives We evaluated the Determine ® HIV1/2 Ag/Ab Combo Rapid Test (Combo RT), a 4th generation test against two 3rd generation tests (SENSA-HIV1/2/0 Tri-line, SD-Bioline) for early detection of HIV-infection in pregnancy. Study design In a cohort study, plasma samples from 32 pregnant women who seroconverted at a subsequent antenatal visit (incident-infection), samples from 189 women who tested HIV positive at baseline (established-infections) and samples from 32 women remaining HIV-seronegative at a subsequent antenatal visit were tested with 3rd generation (antibody detection only) and 4th generation (antibody/antigen detection) rapid HIV tests. The HIV-1 NucliSENSEasyQ ® v2.0 PCR test was used to quantify HIV-viral copies in women with incident HIV-infections. Results Eighteen of 32 (56.3%) women (incident-infections) had detectable viral copies (baseline); 16 (88.9%) were antibody reactive with the Combo RT. None of the 32 specimens were reactive on the antigen component of the Combo RT. The sensitivity and specificity of the Combo RT in detecting HIV infections prior to seroconversion is 59.4% (95%CI 40.6–76.3) and 96.9% (95%CI 83.8–99.9) respectively. The Combo RT detected 94.0% of all HIV-infections if used as a screening test (baseline) compared to 85.5% detected by 3rd generation tests. Conclusions The Combo RT does not identify AHI but is superior to 3rd generation tests in detecting HIV antibody responses.