P-B3 Evaluation of an in-house molecular HIV-1 Test to assess Mother-to-Child HIV-1 transmission in angola (the APEHC cohort)

Abstract

HIV-1 mother-to-child transmission (MTCT) rate in Angola was 25% in 2013. Only 17% of the HIV-1-exposed infants received virological testing within 2 months of birth. Our aim was to develop and validate a cost- effective and sensitive molecular test for early infant diagnosis (EID) of HIV-1 infection using dried blood spots (DBS) in Angola. The assay is a qualitative nested PCR based on primers targeting the conserved integrase region of HIV-1 subtypes prevailing in Angola (A, C-J) and B subtype. Analytical sensitivity was determined using DBS spiked with serious dilutions of: (1) reference plasmids containing the integrase gene of subtypes A-J in HIV-1 seronegative blood; (2) ACH-2 cells which contain a single copy of HIV-1B provirus per cell. The clinical sensitivity and specificity was evaluated using 100 HIV-1 positive DBS samples and 50 HIV-seronegative DBS samples from healthy volunteers. Overall, 154 DBS samples from HIV-1-exposed infants enrolled in the Angolan PErinatal HIV Cohort (APEHC) from a municipal Hospital in Luanda (HDP) were screened in triplicate, using chelex-based DNA extraction. HIV-1 serology results at 18 months were used as diagnostic reference. The limit of detection of the assay was 3 HIV-1 proviral copies using ACH-2 cells and 2–10 copies, depending on subtype, using reference plasmids. Clinical sensitivity was 95.7%, 14% of the positive results being obtained from patients with HIV-1 RNA less than 20 copies per milliliter. HIV-1 MTCT rate in the APEHC was 1.9% in 2013 (3 infants infected). HIV-1 infection in infants was detected as early as one month after birth. The cost per test was less than 10€ which compares to 30€ of commercial assays. The high analytical and clinical sensitivities of our test have enabled accurate EID of HIV-1 infection in infants of the APEHC. The low vertical transmission rate within the cohort is consistent with the current high standard of pediatric care provided. The simplicity and cost effectiveness of the assay recommends it for implementation in Angola and other low income countries.