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BackgroundEarly evidence suggested that the impact of the COVID-19 pandemic was less severe in Africa compared to other parts of the world. However, more recent studies indicate higher SARS-CoV-2 infection and COVID-19 mortality rates on the continent than previously documented. Research is needed to better understand SARS-CoV-2 seroprevalence and immunity in Africa. MethodsOur collaboration with the Lagos State COVID-19 Taskforce, enabled secondary analyses of immune responses in healthcare workers (HCWs) and Oxford/AstraZeneca COVID-19 vaccine recipients from the general population across 5 local government areas (LGAs) in Lagos State, Nigeria. Western blots were used to simultaneously detect SARS-CoV-2 spike and nucleocapsid (N) antibodies and stimulation of peripheral blood mononuclear cells with N followed by an IFN-{gamma} ELISA was used to examine T cell responses. FindingsAntibody data demonstrated high SARS-CoV-2 seroprevalence of 71.6% (96/134) in HCWs and 54.8% (63/115) in the general population. Antibodies directed to only SARS-CoV-2 N, suggesting pre-existing coronavirus immunity, were seen in 10.4% (14/134) of HCWs and 20.0% (23/115) of the general population. T cell data showed that IFN-{gamma} responses against SARS-CoV-2 N were robust in detecting exposure to the virus, demonstrating 87.5% sensitivity and 92.3% specificity. InterpretationThese results have important implications for understanding the paradoxical high SARS-CoV-2 infection with low mortality rate in Africa as compared to other parts of the world, as well as for the development of T cell-based diagnostics and vaccines. FundingHarvard University, Motsepe Presidential Research Accelerator Fund for Africa
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BACKGROUND: ATCC HIV-1 drug resistance test kit was designed to detect HIV-1 drug resistance (HIVDR) mutations in the protease and reverse transcriptase genes for all HIV-1 group M subtypes and circulating recombinant forms. The test has been validated for both plasma and dried blood spot specimen types with viral load (VL) of ≥1000 copies/ml. We performed an in-country assessment on the kit to determine the genotyping sensitivity and its accuracy in detecting HIVDR mutations using plasma samples stored under suboptimal conditions. METHODS: Among 572 samples with VL ≥1000 copies/ml that had been genotyped by ViroSeq assay, 183 were randomly selected, including 85 successful genotyped and 98 unsuccessful genotyped samples. They were tested with ATCC kits following the manufacturer's instructions. Sequence identity and HIVDR patterns were analysed with Stanford University HIV Drug Resistance HIVdb program. RESULTS: Of the 183 samples, 127 (69.4%) were successfully genotyped by either method. While ViroSeq system genotyped 85/183 (46.5%) with median VL of 32,971 (IQR: 11,150-96,506) copies/ml, ATCC genotyped 115/183 (62.8%) samples with median VL of 23,068 (IQR: 7,397-86,086) copies/ml. Of the 98 unsuccessful genotyped samples with ViroSeq assay, 42 (42.9%) samples with lower median VL of 13,906 (IQR: 6,122-72,329) copies/ml were successfully genotyped using ATCC. Sequence identity analysis revealed that the sequences generated by both methods were >98% identical and yielded similar HIVDR profiles at individual patient level. CONCLUSION: This study confirms that ATCC kit showed greater sensitivity in genotyping plasma samples stored in suboptimal conditions experiencing frequent and prolonged power outage. Thus, it is more sensitive particularly for subtypes A and A/G HIV-1 in resource-limited settings.
