Evaluation of multi-assay algorithms for identifying individuals with recent HIV infection: HPTN 071 (PopART)

Abstract

Background: Assays and multi-assay algorithms (MAAs) have been developed for population-level cross-sectional HIV incidence estimation. These algorithms use a combination of serologic and/or non-serologic biomarkers to assess the duration of infection. We evaluated the performance of four MAAs for individual-level recency assessments.

Methods: Samples were obtained from 220 seroconverters (infected <1 year) and 4,396 non-seroconverters (infected >1 year) enrolled in an HIV prevention trial (HPTN 071 [PopART]); 28.6% of the seroconverters and 73.4% of the non-seroconverters had HIV viral loads ≤400 copies/mL. Samples were tested with two laboratory-based assays (LAg-Avidity, JHU BioRad-Avidity) and a point-of-care assay (rapid LAg). The four MAAs included different combinations of these assays and HIV viral load. Seroconverters on antiretroviral treatment (ART) were identified using a qualitative multi-drug assay.

Results: The MAAs identified between 54 and 100 (25% to 46%) of the seroconverters as recently-infected. The false recent rate of the MAAs for infections >2 years duration ranged from 0.2%-1.3%. The MAAs classified different overlapping groups of individuals as recent vs. non-recent. Only 32 (15%) of the 220 seroconverters were classified as recent by all four MAAs. Viral suppression impacted the performance of the two LAg-based assays. LAg-Avidity assay values were also lower for seroconverters who were virally suppressed on ART compared to those with natural viral suppression.

Conclusions: The four MAAs evaluated varied in sensitivity and specificity for identifying persons infected <1 year as recently infected and classified different groups of seroconverters as recently infected. Sensitivity was low for all four MAAs. These performance issues should be considered if these methods are used for individual-level recency assessments.

Fig 1. Samples included in the analysis.

The figure shows the process used to select samples for analysis. Abbreviations: N: number; PC: Population Cohort; PC12: study visit in HPTN 071 (PopART) after 12 months of study intervention; PC24: study visit in HPTN 071 (PopART) after 24 months of study intervention; VL: viral load; BioRad: JHU BioRad-Avidity assay; LAg: LAg-Avidity assay; NSC: non-seroconverter; SC: seroconverter.

Fig 2. Comparison of the subsets of seroconverters identified as recently infected using four MAAs.

The Venn diagram shows the number of seroconverters who were classified as recently infected using one or more of the four MAAs. Thirty-two of the 220 seroconverters (15%) were classified as recently infected by all four MAAs. Abbreviations: LAg: limiting antigen assay, MAA: multi-assay algorithm.