We identified a cluster of mpox exposures among key populations in Kenya through retrospective serologic screening. We identified strong seropositivity among sex workers and gay, bisexual, and other men who have sex with men. These findings demonstrate the need for increased mpox surveillance among mpox-endemic and mpox-endemic-adjacent regions in Africa.

There are marked differences in the spread and prevalence of HIV-1 subtypes worldwide, and differences in clinical progression have been reported. However, the biological reasons underlying these differences are unknown. Gag-protease is essential for HIV-1 replication, and Gag-protease-driven replication capacity has previously been correlated with disease progression. We show that Gag-protease replication capacity correlates significantly with that of whole isolates (r = 0.51; P = 0.04), indicating that Gag-protease is a significant contributor to viral replication capacity. Furthermore, we investigated subtype-specific differences in Gag-protease-driven replication capacity using large well-characterized cohorts in Africa and the Americas. Patient-derived Gag-protease sequences were inserted into an HIV-1 NL4-3 backbone, and the replication capacities of the resulting recombinant viruses were measured in an HIV-1-inducible reporter T cell line by flow cytometry. Recombinant viruses expressing subtype C Gag-proteases exhibited substantially lower replication capacities than those expressing subtype B Gag-proteases (P < 0.0001); this observation remained consistent when representative Gag-protease sequences were engineered into an HIV-1 subtype C backbone. We identified Gag residues 483 and 484, located within the Alix-binding motif involved in virus budding, as major contributors to subtype-specific replicative differences. In East African cohorts, we observed a hierarchy of Gag-protease-driven replication capacities, i.e., subtypes A/C < D < intersubtype recombinants (P < 0.0029), which is consistent with reported intersubtype differences in disease progression. We thus hypothesize that the lower Gag-protease-driven replication capacity of subtypes A and C slows disease progression in individuals infected with these subtypes, which in turn leads to greater opportunity for transmission and thus increased prevalence of these subtypes.IMPORTANCE HIV-1 subtypes are unevenly distributed globally, and there are reported differences in their rates of disease progression and epidemic spread. The biological determinants underlying these differences have not been fully elucidated. Here, we show that HIV-1 Gag-protease-driven replication capacity correlates with the replication capacity of whole virus isolates. We further show that subtype B displays a significantly higher Gag-protease-mediated replication capacity than does subtype C, and we identify a major genetic determinant of these differences. Moreover, in two independent East African cohorts we demonstrate a reproducible hierarchy of Gag-protease-driven replicative capacity, whereby recombinants exhibit the greatest replication, followed by subtype D, followed by subtypes A and C. Our data identify Gag-protease as a major determinant of subtype differences in disease progression among HIV-1 subtypes; furthermore, we propose that the poorer viral replicative capacity of subtypes A and C may paradoxically contribute to their more efficient spread in sub-Saharan Africa.

Pre-exposure prophylaxis (PrEP) is highly effective at reducing HIV acquisition. We aimed to estimate usage of oral-PrEP, and factors associated with adherence among female sex workers (FSWs) in Nairobi, Kenya, using a novel point-of-care urine tenofovir lateral flow assay (LFA). The Maisha Fiti study randomly selected FSWs from Sex Worker Outreach Program clinics in Nairobi. Data were collected from 1003 FSWs from June-October 2019, including surveys on self-reported oral-PrEP adherence. Adherence was also measured using the LFA for HIV-negative FSWs currently taking oral-PrEP. Informed by a social-ecological theoretical framework, we used hierarchical multivariable logistic regression models to estimate associations between individual, interpersonal/community, and structural/institutional-level factors and either self-reported or LFA-assessed adherence. Overall, 746 HIV-negative FSWs aged 18-40 participated in the study, of whom 180 (24.1%) self-reported currently taking oral-PrEP. Of these, 56 (31.1%) were adherent to oral-PrEP as measured by LFA. In the multivariable analyses, associations with currently taking oral-PrEP included having completed secondary education, high alcohol/substance use, feeling empowered to use PrEP, current intimate partner, no recent intimate partner violence, having support from sex worker organisations, experiencing sex work-related stigma, and seeking healthcare services despite stigma. Associations with oral-PrEP LFA-measured adherence measured included having only primary education, experience of childhood emotional violence, belonging to a higher wealth tertile, and being nulliparous. Oral-PrEP adherence, measured by self-report or objectively, is low among FSWs in Nairobi. Programs to improve oral-PrEP usage among FSWs should work to mitigate social and structural barriers and involve collaboration between FSWs, healthcare providers and policymakers.

Some people remain healthier throughout life than others but the underlying reasons are poorly understood. Here we hypothesize this advantage is attributable in part to optimal immune resilience (IR), defined as the capacity to preserve and/or rapidly restore immune functions that promote disease resistance (immunocompetence) and control inflammation in infectious diseases as well as other causes of inflammatory stress. We gauge IR levels with two distinct peripheral blood metrics that quantify the balance between (i) CD8⁺ and CD4⁺ T-cell levels and (ii) gene expression signatures tracking longevity-associated immunocompetence and mortality-associated inflammation. Profiles of IR metrics in ~48,500 individuals collectively indicate that some persons resist degradation of IR both during aging and when challenged with varied inflammatory stressors. With this resistance, preservation of optimal IR tracked (i) a lower risk of HIV acquisition, AIDS development, symptomatic influenza infection, and recurrent skin cancer; (ii) survival during COVID-19 and sepsis; and (iii) longevity. IR degradation is potentially reversible by decreasing inflammatory stress. Overall, we show that optimal IR is a trait observed across the age spectrum, more common in females, and aligned with a specific immunocompetence-inflammation balance linked to favorable immunity-dependent health outcomes. IR metrics and mechanisms have utility both as biomarkers for measuring immune health and for improving health outcomes.