Improved Testing of Recent HIV-1 Infections with the BioRad Avidity Assay Compared to the Limiting Antigen Avidity Assay and BED Capture Enzyme Immunoassay: Evaluation Using Reference Sample Panels from the German Seroconverter Cohort

Abstract

BackgroundThe variety and limitations of current laboratory methods for estimating HIV-incidence has driven attempts to improve and standardize the performance of serological ‘Tests for Recent HIV-Infections’ (TRI). Primary and follow-up HIV-1 positive plasma samples from individuals with well-defined dates of infection collected as part of the German Seroconverter Cohort provided specimens highly suitable for use in comparing the performance of three TRIs: the AWARE™ BED™ EIA HIV-1 Incidence test (BED-CEIA), Genetic systems HIV-1/HIV-2 Plus O EIA antibody avidity-based assay (BioRad Avidity) and Sedia™ HIV-1 LAg Avidity EIA (LAg Avidity).MethodsThe evaluation panel included 180 specimens: 44 from antiretroviral (ARV)-naïve individuals with recently acquired HIV-infection (≤130 days; 25 B and 19 non-B subtypes) and 136 from long-term (>12 months) infected individuals [101 ARV-naïve subtype B, 16 non-B subtypes, 14 ARV-treated individuals, 5 slow progressors (SLP)].ResultsFor long-term infected, ARV-naïve individuals the false recent rates (FRR) of both the BioRad and LAg Avidity assays were 2% (2/101 for subtype B) and 6% (1/16 for subtype ‘non-B’), while the FRR of the BED-CEIA was 7% (7/101 for subtype B) and 25% (4/16 for subtype ‘non-B’) (all p>0.05). Misclassification of ARV-treated individuals and SLP was rare by LAg (1/14, 0/5) and BioRad Avidity assays (2/14, 1/5) but more frequent by BED-CEIA (5/14, 3/5). Among recently-infected individuals (subtype B), 60% (15/25) were correctly classified by BED-CEIA, 88% (22/25) by BioRad Avidity and significantly fewer by LAg (48%, 12/25) compared to BioRad Avidity (p = 0.005) with a higher true-recency rate among non-B infections for all assays.ConclusionsThis study using well-characterized specimens demonstrated lower FRRs for both avidity methods than with the BED-CEIA. For recently infected individuals the BioRad Avidity assay was shown to give the most accurate results.

Assessment of Ambiguous Base Calls in HIV-1 pol Population Sequences as a Biomarker for Identification of Recent Infections in HIV-1 Incidence Studies

“…The discordance between the SAM and the BED-CEIA was caused mainly by a recent result with the SAM and a nonrecent result with the BED-CEIA, which is also in agreement with the related study (15). Referring to previously published data (2,24,25) and our subset analyses, the BED-CEIA yields significantly higher accuracy and a lower false recency rate than the SAM and the multianalyte algorithm that includes the SAM. Moreover, with the SAM, the probability of a sample being classified as recent showed a broad distribution over the duration of infection.…”

“…However, the SAM achieved a lower accuracy than serological HIV-1 incidence assays (2,3,24,25) and demonstrated an inconveniently broad distribution of individual durations of recency. Moreover, the SAM would not be cost-effective if HIV-1 genotyping was performed solely for cross-sectional surveys to estimate HIV-1 incidence.…”

Development of an avidity assay for detection of recent HIV infections

“…These three patients comprised of different subtypes (B, A and CRF-02 AG) and all had a viral load <50 copies/ml. Studies have shown that subtype A and/or low viral load can be contributing factors that result in false recent AI in established infections (Laeyendecker et al, 2012;Hauser et al, 2014;Kassanjee et al, 2014). The FRR of our assay at less than 1% is one of the lowest described for HIV Incidence assays (Suligoi et al, 2002;Doung et al, 2012).…”

“…Based on combined assessment of retrospective and prospective HIV samples, the FRR of the assay is 0.89% (95% CI: 0.24-2.3%). Low CD4 count, antiretroviral therapy, AIDS-defining illness, elite controllers, undetectable viral load and HIV subtypes can influence the FRR of incidence assays (Chawla et al, 2007;Selleri et al, 2007;Re et al, 2010;Poropatich and Sullivan, 2011;Chaillon et al, 2012;Laeyendecker et al, 2012;Hauser et al, 2014). Only three longstanding HIV infected patients from the retrospective study had a low AI.…”

Strengthening HIV surveillance: measurements to track the epidemic in real time

“…The greater the proportion of high avidity antibodies remaining bound increases the avidity index, therefore indicating established (long term) infection (Suligoi et al, 2002). The Bio-Rad Avidity EIA is a modification of the GS HIV-1/HIV-2 Plus O EIA (Redmond, MA) (Hauser et al, 2014). This assay uses 0.1M diethylamine (DEA) to dissociate low avidity antibodies characteristic of recent infection.…”