Performance Characteristics of an HIV-1 Rapid Recency Assay Among Treatment-Naïve Individuals

Asanté HIV-1 Rapid Recency Assay identifies HIV-1 recent infection based on antibody avidity among newly diagnosed individuals. We estimated the mean duration of recent infection (MDRI), false recency rate (FRR), the probability of being classified as recent over time and examined the assay reproducibility. A total of 967 longitudinal plasma specimens from 180 HIV-1 seroconverting individuals, all antiretroviral treatment (ART) naïve, from multiple countries were used to determine the MDRI, while cross-sectional plasma specimens from individuals infected for >1 year (total n = 1,285; n = 926 without AIDS; n = 359 with AIDS; all ART naïve) were tested to estimate the FRR. All specimens were tested by two testers and results were interpreted visually, followed by a line intensity reader. Linear interpolation and polynomial regression were used to estimate the duration of recent infection by subject. MDRI was calculated as a mean of individual duration of recency while FRR was calculated as a fraction of long-term (LT) cases that were misclassified as recent. The LT line intensity, a reflection of antibody avidity, demonstrated an overall increase over time, especially during the first year after seroconversion. The MDRI was 160 days [95% confidence interval (CI), 140-181] by linear interpolation and 167 days (95% CI, 147-187) by polynomial regression among ART-naïve cases. Probability of individuals testing as recent infection was 97.9% (95% CI, 93.9%-99.3%) by 1 month post-seroconversion and decreased to 10.3% (95% CI, 6.3%-16.5%) by 12 months. FRR was 2.1% (95% CI, 1.3%-3.2%) among ART-naïve individuals infected >1 year and 5.1% (95% CI, 3.4%-7.8%) among patients with AIDS. The assay indicated high inter-tester reproducibility of 96.2%. It can be a valuable tool for program-based HIV-1 recent infection surveillance for a better understanding of risk factors of acquiring new infections. Our study provides evidence about the performance of the assay for data interpretation of recency surveillance among newly diagnosed individuals.