Immunoblots may not be effective in confirming the recency of HIV-1 infection.

Recently, immunoblots (IBs) have tended to substitute Western blots (WBs) for HIV infection diagnosis. Several studies have confirmed IBs' high sensitivity to confirm HIV infection for every stage. Since the nature and pattern of the antigens of IBs are different from those of WB, the abilities of IBs and WBs to distinguish the stages of recent seroconversion and open-ended chronic infection might differ. We aimed to evaluate the performance of two IBs (INNO-LIA™ HIVI/II, Fujirebio, and Geenius™ HIV1/2 Confirmatory assay, Bio-Rad) to define the stage of infection. We studied 53 patients from the French ANRS CO6 PRIMO cohort. IBs have higher positive rates than WB. However, Geenius was less sensitive than WB and INNO-LIA to detect antibodies to p31 (0% vs 22.6 % and 15.1 %, respectively), so it could wrongly label late Fiebig stage and open-ended chronic infections as recent infections (n = 5/53). For the first time, we provide evidence that centralized WBs associated with an enzyme immunoassay for the identification of recent HIV-1 infection support the establishment of a more accurate diagnosis of primary HIV infection to improve the accuracy of enrollments in cohorts of recent HIV infections useful for epidemiological studies, pathogenesis studies or therapeutic trials.