Performance of serological and molecular tests within acute HIV infection.

BACKGROUND: Early diagnosis of acute HIV infection can be challenging and is critical in regards to early therapeutic decision making. OBJECTIVES: To evaluate the performance of different HIV tests in detecting early infections. STUDY DESIGN: A total of 83 leftover specimens of 61 study participants who seroconverted were used in this sub-study. 35 HIV RNA positive but still seronegative specimens (acute infections) were used for analysis of the sensitivity of the different assays in detecting early infections and 42 HIV RNA and antibody negative specimens were used for specificity analysis. RESULTS: Four (11%) specimens out of 35 acute infections were reactive with the Enzygnost® Anti-HIV 1/2 Plus and 12/35 (34%) with the Vironostika® HIV Ag/Ab. 16 (46%) specimens were confirmed as acute by the INNOTEST® HIV antigen mAb Antigen test. Only three (9%), 10 (29%) and 9 (27%) specimens were reactive with the Determine HIV-1/2 Ag/Ab Combo, SD Bioline HIV Ag/Ab Combo test and the HIV Combo test, respectively. The specificity of the different tests were 100%, 95%, 100%, 93%, 100% and 93% for Enzygnost® Anti-HIV 1/2 Plus, Vironostika® HIV Ag/Ab, INNO-Test HIV antigen mAb, Determine HIV-1/2 Ag/Ab Combo, SD Bioline HIV Ag/Ab Combo test and HIV Combo test respectively. CONCLUSION: RNA test, 4th generation ELISA and Single Ag test are the most sensitive tests for detection of an acute infection. As an alternative, the HIV Combo test is generally slightly more sensitive compared to its previous version, but the SD Bioline HIV Ag/Ab Combo tests has the best performance compared to the other simple rapid tests (SRTs) but none of them are precise in detecting Ag in the determination of acute infections.

Detection of new HIV infections in a multicentre HIV antiretroviral pre-exposure prophylaxis trial.

BACKGROUND: Monthly specimens collected from FEM-PrEP-a Phase III trial [1] were investigated for the detection of acute HIV (AHI) infection. OBJECTIVES: To evaluate the efficiency of the study-specific HIV algorithm in detecting AHI, and the performance of each of the serological and molecular tests used in diagnosing new infections, and their contribution to narrowing the window period. STUDY DESIGN: A total of 83 pre-seroconversion specimens from 61 seroconverters from the FEM-PrEP trial were further analyzed in a sub-study. During the trial, HIV seroconversion was diagnosed on site using a testing algorithm with simple/rapid tests (SRTs) and confirmed with a gold standard testing algorithm (see short communication: Fig. 1). The infection date was determined more accurately by the use of standard ELISAs and Nucleic Acid Amplification Tests (NAAT) in a look-back procedure. For this sub-study, the international central laboratory repeated the study algorithm using SRTs. RESULTS: A total of 83 pre-seroconversions specimens from 61 seroconverters were analyzed in a look-back procedure. RNA was detected in 35/61 seroconverters at the visit before the seroconversion visit as determined at the study sites. Four seroconversion dates were inaccurate at one study site as the international central laboratory detected the HIV infection one visit earlier using the same test algorithm. Using the gold standard, an additional seroconversion was detected at an earlier visit. The combined antigen/antibody and the single antigen test had a higher sensitivity compared to the SRTs in detecting acute infections. CONCLUSIONS: In the FEM-PrEP trial, the international central laboratory detected a small number of seroconversions one month earlier than the study sites using the same study algorithm. Standard tests are still the most sensitive tests in detecting pre-seroconversion or acute HIV infection, but they are costly, time consuming and not recommended for use on-site in a clinical trial.