EVALUATION OF AN IN-HOUSE PROBE-BASED REAL-TIME PCR TEST FOR EARLY INFANT HIV-1 DIAGNOSIS IN UGANDA

Abstract

Background: HIV infection remains a problem worldwide, with the majority of the cases being in resource-limited settings. Pediatric HIV testing is lagging with only 43 % of HIV-exposed infants being tested within the recommended first two months of life. One of the major barriers to the elimination of this infection is the low coverage of Nucleic Acid Amplification tests which is crucial in the elimination of the infection. The Locked Nucleic acid Real-time PCR is a modification of the Taqman assay which uses Locked Nucleic Acid Analogs in Primer design. This reduces on primer length and overall primer cost and maintains stability of the primers and probes. This test had however not been evaluated to validate its performance in a clinical setting in Uganda. The aim of this study was to validate an in-house designed LNA probe-based real-time PCR test for early Infants HIV-1 diagnosis in Uganda Methods: This was a cross-sectional validation study conducted in two phases at Uganda National Health Laboratories Services and MBN laboratories on samples collected from Kampala, Wakiso and a few health centers from northern Uganda in February. Phase I was aimed at the determination of the proportion of known positive and negative samples. Phase II evaluated the accuracy of the LNA Real-time PCR in an unknown result population. Data were analyzed by SPSS and Meta Disc to generate Sensitivity, specificity, Kappa agreement, Positive and Negative Predictive values. Cost analysis was done by listing all items used in the new test and costing them. Results: The LNA HIV DNA PCR detected a proportion of 93.3% (28 of the 30) known positives and 100 %( 43) of the known negative samples in phase I. The test produced sensitivity of 94.1%(95%C1,80.3 - 99.3) , specificity of 100%(95%C1,98 - 100), Kappa agreement of 0.98, positive and negative predictive values of 100% (95%C1,98 - 100) and 98.8 %(95%C1,97 - 100) respectively. The unit cost was computed at approximately UGX 13,204.443 equivalent to USD 3.5. Conclusion: The LNA HIV DNA PCR technique was found to be highly accurate for the diagnosis of HIV infection in infants less than 18 months of age. The assay could be an alternative test for screening of HIV infection especially in resource-limited settings.