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Background: Viral suppression and viral breakthrough impact the humoral immune response to HIV infection. We evaluated the impact of viral suppression and viral breakthrough on results obtained with two cross-sectional HIV incidence assays., Methods: All samples were collected from adults in the US who were HIV infected for >2 years. Samples were tested with the BED capture enzyme immunoassay (BED-CEIA) which measures the proportion of IgG that is HIV-specific, and with an antibody avidity assay based on the Genetic Systems 1/2+ O ELISA. We tested 281 samples: (1) 30 samples from 18 patients with natural control of HIV-1 infection known as elite controllers or suppressors (2) 72 samples from 18 adults on antiretroviral therapy (ART), with 1 sample before and 2-6 samples after ART initiation, and (3) 179 samples from 20 virally-suppressed adults who had evidence of viral breakthrough receiving ART (>400 copies/ml HIV RNA) and with subsequent viral suppression., Results: For elite suppressors, 10/18 had BED-CEIA values <0.8 normalized optical density units (OD-n) and these values did not change significantly over time. For patients receiving ART, 14/18 had BED-CEIA values that decreased over time, with a median decrease of 0.42 OD-n (range 0.10 to 0.63)/time point receiving ART. Three patterns of BED-CEIA values were observed during viral breakthrough: (1) values that increased then returned to pre-breakthrough values when viral suppression was re-established, (2) values that increased after viral breakthrough, and (3) values that did not change with viral breakthrough., Conclusions: Viral suppression and viral breakthrough were associated with changes in BED-CEIA values, reflecting changes in the proportion of HIV-specific IgG. These changes can result in misclassification of patients with long-term HIV infection as recently infected using the BED-CEIA, thereby influencing a falsely high value for cross-sectional incidence estimates.

BackgroundIn the HIV Prevention Trials Network (HPTN) 061 study, 8 (2.3%) of 348 HIV-infected participants identified as HIV uninfected at study enrollment using a single HIV rapid test for screening were found to be HIV infected after additional testing.ObjectivesTo evaluate the performance of different HIV assays for detection of HIV infection in HPTN 061 participants with missed infection and individuals with viral suppression.MethodsPlasma samples from 8 HPTN 061 participants, 17 elite controllers, and 101 individuals on antiretroviral treatment (ART) were tested for HIV with 3 rapid tests, 2 laboratory-based immunoassays, and a Western blot assay. The HPTN 061 samples were also tested with 2 HIV RNA assays and an antiretroviral drug assay.ResultsOf the 8 HPTN 061 participants with missed infection, 1 was an elite controller, 1 was taking ART, 2 were missed because of testing or clerical errors, 1 had recent HIV infection (identified using a multi-assay algorithm), and 3 had acute HIV infection. Two (1.7%) of 118 individuals with viral suppression (both taking ART) had at least 1 false-negative test.ConclusionsIn clinical trials, HIV infections can be missed for a variety of reasons. Using more than one assay to screen for HIV infection may reduce the number of missed infections.