Project Details

Alternative diagnostic markers for HIV in persistently seronegative HIV-infected children put early on cART

Paul Alain Tagnouokam Ngoupo, PhD

Summary

BACKGROUND: Early treatment of HIV-1 infection affects levels of HIV antibodies leading to trace amounts of antibodies not detectable by current standard serological assays and this could lead to inadequate treatment interruption in the children. GAP: Do seronegative HIV-infected children initiated on early cART produce HIV antibodies and antigens that currently available HIV serological assays fail to detect? HYPOTHESIS: Due to the restrictive effect of early cART on HIV reservoir and load, HIV-seronegative individuals do produce antibodies/antigens but at levels undetectable by current diagnostic assays. METHODS: For this study, all HIV infected children of the ANRS PEDIACAM cohort in Cameroon with persistent seronegative status was paired to HIV-seropositive infants. We developed an in-house ELISA protocol to determine if seronegative HIV-infected children produce HIV antibodies or antigens at a level that is not detected by current assays and to investigate the relation between anti-HIV antibody response or presence of HIV Ag and biological/clinical characteristics of infants. RESULTS: We developed an optimized indirect ELISA protocol to address limitations in detecting low-titer HIV-specific antibodies. The assay was validated with 60 plasma samples, demonstrating high sensitivity and specificity for multiple HIV antigens. Viral lysate and GP41 showed excellent sensitivity (100%) and specificity (93.3%-96.7%), while P24 had moderate sensitivity (63.3%) but maintained high specificity (96.7%). The assay's reliability makes it suitable for detecting low-level antibodies missed by standard tests. Evaluation on 77 plasma samples from the PEDIACAM cohort revealed that the assay detected HIV-specific antibodies in 68% of children classified as seronegative by commercial tests, uncovering humoral responses typically overlooked. Results were independent of immuno-virologic factors like CD4 counts, viral loads, sex, or ART initiation age, showing robust performance across diverse conditions. IMPACT: Currently, standard serological assays may fail to detect HIV in 4 out of every 10 infants due to the early initiation of antiretroviral (ARV) treatment. This innovative assay demonstrates significant potential to enhance HIV diagnostics, particularly in complex cases during this era of early combination antiretroviral therapy (cART) initiation. Its use could help prevent inadequate treatment interruptions, thereby simplifying and improving the overall management of the infection.