Chikungunya intra-vector infection dynamics in a French Aedes albopictus population reveals low vector barrier intensity and supports an explosive epidemic potential

<p>Arbovirus emergence and epidemic potential, as approximated by the vectorial capacity formula, depends on host and vector parameters, including the vector&rsquo;s intrinsic ability to replicate then transmit the pathogen known as vector competence. Vector competence is a complex, time-dependent, quantitative phenotype influenced by biotic and abiotic factors. A combination of experimental and modelling approaches is required to assess arbovirus intra-vector dynamics and estimate its epidemic potential. In this study, we measured infection, dissemination, and transmission dynamics of chikungunya virus (CHIKV) in a field-derived&nbsp;<em>Aedes albopictus</em>&nbsp;population (Lyon metropolis, France) after oral exposure to a range of virus doses spanning human viraemia. Statistical modelling indicates rapid and efficient CHIKV progression in the vector mainly due to an absence of a dissemination barrier, with 100% of the infected mosquitoes ultimately exhibiting a disseminated infection, regardless of the virus dose. Transmission rate data revealed a time-dependent, but overall weak, transmission barrier, with individuals transmitting as soon as 2 days post-exposure (dpe) and &gt;50% infectious mosquitoes at 6 dpe for the highest dose. Based on these experimental intra-vector dynamics data, epidemiological simulations conducted with an agent-based model showed that even at low mosquito biting rates, CHIKV could trigger explosive outbreaks. Together, this reveals the high epidemic potential of CHIKV upon transmission by&nbsp;<em>Aedes albopictus</em>&nbsp;in mainland France.</p>