Vector competence of Aedes albopictus from Northern, Southeastern, and Southern Brazil for locally circulating East-Central-South African and Asian genotypes of Chikungunya virus.

Aedes albopictus, an invasive mosquito species prevalent across Brazil, serves as a crucial vector for numerous arboviruses, including Chikungunya virus (CHIKV). Following the introduction of Asian and East-Central-South African (ECSA) genotypes in 2014, Brazil has faced escalating CHIKV epidemics, underscoring the critical need to understand region-specific vector competence. Building upon previous research that indicated variable vector competence, this study evaluated the susceptibility and dissemination rates of Aedes albopictus populations from diverse Brazilian regions (Belém, Paraná and Rio de Janeiro) to locally circulating ECSA and Asian CHIKV genotypes. Body, leg (dissemination), and saliva (transmission) positivity rates were measured at 3, 5, and 13 days post-infection. Despite descriptive heterogeneity, there was no significant effect of time, population, or genotype on initial CHIKV infection rates in mosquito bodies, with over 80% of individuals infected as early as 3 days post-infection, suggesting highly permissive midguts. In contrast, CHIKV dissemination to the legs was significantly influenced by both time post-infection (showing progressive increase) and mosquito population (Paraná exhibited significantly higher rates than Belém), but not by virus genotype, indicating population-specific variations in systemic viral spread. Crucially, saliva positivity rates were consistently low across all tested populations and genotypes, being substantially lower than those observed in bodies and legs but showed no significant effect of time, population origin, or virus genotype on overall saliva positivity rates. Understanding these population-specific vector dynamics is critical for refining predictive models, accurately assessing regional outbreak risks, and developing public health interventions against CHIKV in Brazil.