CROI 2025 Abstract eBook

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Poster Abstracts

1158 Distribution of HIV-1 Variants in Population-Based National Surveys in Sub-Saharan Africa, 2015-2022 Peter D. Ghys 1 , Jessica E. Justman 2 , Andrew C Voetsch PhD 3 , Alash'le Abimiku 4 , Sani Aliyu 5 , Hetal Patel 3 , Joshua DeVos 3 , Kristin Brown 3 , Faith Ussery 3 , Bharat Parekh 3 , Chéri van der Walt 6 , Vibha Kana 6 , Sizulu Moyo 7 , Mary Mahy 8 , Joris Hemelaar 9 1 Independent Consultant, Tannay, Switzerland, 2 ICAP at Columbia University, New York, NY, USA, 3 Centers for Disease Control and Prevention, Atlanta, GA, USA, 4 University of Maryland, Baltimore, MD, USA, 5 National Agency for the Control of AIDS, Abuja, Nigeria, 6 National Institute for Communicable Diseases, Johannesburg, South Africa, 7 Human Sciences Research Council, Pretoria, South Africa, 8 United Nations Programme on HIV/AIDS, Geneva, Switzerland, 9 University of Oxford, Oxford, UK Background: The distribution of HIV-1 genetic variants among people living with HIV (PLHIV) is important for the design of vaccines and broadly neutralising antibodies (bNAbs) as well as for the accuracy of tests for diagnosis and viral load. This study aimed to compare the distribution of HIV-1 variants from population-based national surveys in sub-Saharan countries. Methods: Population-based national HIV survey data were available for 15 countries in sub-Saharan Africa during 2015-2022, including Population based HIV Impact Assessments (PHIAs) in several countries, Nigeria’s HIV/ AIDS Indicator and Impact Survey (NAIIS) and two South African National HIV Prevalence, Incidence and Behaviour Surveys (SABSSM). The Ethiopia survey was conducted in only urban areas. Genotyping was performed on the samples selected for resistance testing and in which amplification of HIV RNA/proviral DNA was successful. In most countries, samples from those with a recent HIV infection within the prior 12 months (applying an algorithm that included the Limiting-Antigen Avidity EIA, viral load, and the absence of antiretrovirals), all children younger than 18 months (except for Rwanda), and a country-specific selection of people living with HIV (PLHIV) with a long-standing infection (beyond 12 months) with VL>1,000 RNA copies/ml were analysed. In the two SABSSMs, the sampling included PLHIV with >1,000 RNA copies/ml. HIV-1 variants were identified using the REGA HIV-1 & 2 Automated Subtyping Tool. The unweighted percentage distribution of HIV-1 variants was determined for each survey and compared to other surveys. Results: Sample sizes varied between 42 and 1,440 PLHIV by survey (Figure). Comparing country distributions of HIV-1 variants showed important variation among countries and regions: the dominant variant was the recombinant CRF02 AG in Cameroon, Côte d’Ivoire and Nigeria; subtype A in Kenya, Rwanda and Uganda; subtype C (40%) and subtype A (38%) in Tanzania and subtype C (>90%) in Ethiopia, Eswatini, Lesotho, Malawi, Namibia, South Africa (both surveys), Zambia and Zimbabwe. Conclusions: HIV-1 variant distributions for countries in West Africa, East Africa, Ethiopia, and Southern Africa in population-based national surveys showed heterogeneity across these regions, with specific subtypes dominating in each region. HIV-1 diversity in sub-Saharan Africa may need to be accounted for during the development of HIV diagnostic and viral load tests, vaccines, and bNAbs.

1157 People Living With HIV Diagnosed Late Provide Source of HIV Infection to Others With Recent Diagnosis Evangelia G. Kostaki 1 , Georgios Adamis 2 , Maria Chini 3 , Simeon Metallidis 4 , Vasileios Papastamopoulos 5 , Dimitrios Chatzidimitriou 4 , Antonios Papadopoulos 1 , Mina Psichogiou 1 , Dimitra Paraskeva 6 , Sofia Kourkounti 7 , Helen Sambatakou 1 , Angelos Hatzakis 1 , Gkikas Magiorkinis 1 , Lemonia Skoura 4 , Dimitrios Paraskevis 1 1 National and Kapodistrian University of Athens, Athens, Greece, 2 General Hospital of Athens "G. Gennimatas", Athens, Greece, 3 Red Cross Athens General Hospital, Athens, Greece, 4 Aristotle University of Thessaloniki, Thessaloniki, Greece, 5 Evaggelismos General Hospital, Athens, Greece, 6 National Public Health Organization, Marousi, Greece, 7 Andreas Syngros Hospital of Veneral and Dematological Diseases, Athens, Greece Background: Late presentation remains an important hurdle in the management and prevention of HIV infection. Our aim was to investigate the potential source of infection among people living with HIV (PLHIV) with different stages of diagnosis, using in addition to the traditional definition for late diagnosis, the time interval between HIV acquisition and diagnosis dates. Methods: The study sample consisted of 3,093 HIV-1 subtype A1 and B sequences from a period with dense sampling in Greece. Analysis was performed on 2,385 sequences with pairwise genetic distances <0.015 substitutions/site. 2,194 PLHIV were categorized according to CD4 count at diagnosis (advanced disease: CD4<200 cells/μl or clinical AIDS, late: 200≤CD4≤350 cells/μl, non-late: CD4>350 cells/μl). Treatment-naïve PLHIV were categorized according to the time from HIV infection to diagnosis (recent: 0.07-1.20, intermediate: 1.21-2.55, late: 2.56-11.71 years). HIV infection was estimated by molecular clock analysis. HIV transmissions among PLHIV with different diagnosis status were estimated by a modified statistical phylogeography method. Results: For subtype A1, analysis using the estimated infection dates revealed that among PLHIV with recent diagnosis, the mean number of infections originated from PLHIV with late and intermediate diagnosis were 35.7 (11%) and 32.8 (10%), respectively. For those diagnosed late, only 21.3 (6.7%) and 18.5 (5.8%) of infections were from PLHIV with intermediate and early diagnosis. Similarly for subtype B, a proportion of infections among PLHIV with recent (13%) and intermediate (17.5%) diagnoses originated from PLHIV with late status. Statistical phylogeography confirmed that late presenters were a significant source of HIV transmission to PLHIV from other groups. Analysis using CD4 counts showed consistent results for both subtypes. Late and advanced disease groups provided a significant source of infections to other groups. Non-late presenters were not a significant source of HIV transmission to those with late presentation and advanced disease. Conclusions: Using two different definitions for late diagnosis, we showed that PLHIV diagnosed at a late stage provide a source of infection to those diagnosed earlier, in Greece. Our study highlights that early diagnosis, besides the beneficial effect for the disease prognosis, would significantly mitigate onward HIV transmission. This underscores the need to enhance HIV testing strategies in Greece to ensure earlier diagnosis and timely treatment initiation.

Poster Abstracts

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