Differential Susceptibility of Aedes aegypti and Aedes albopictus Mosquitoes to Infection by Mayaro Virus Strains

Mayaro virus (MAYV) is an arthropod-borne virus (arbovirus) belonging to the family Togaviridae, genus Alphavirus. In recent years, the geographic distribution of MAYV may have expanded north from South and Central America into the Caribbean Islands. Although Haemagogus janthinomys is considered the main vector for MAYV, the virus has also been isolated from other mosquitoes, including Aedes aegypti, a widespread species that serves as the main vector for highly epidemic viruses. Given the possible expansion and outbreaks of MAYV in Latin America, it is possible that MAYV might be adapting to be efficiently transmitted by urban vectors. Therefore, to investigate this possibility, we evaluated the vector competence of Ae. aegypti and Ae. albopictus mosquitoes to transmit MAYV isolated during a year of low or high MAYV transmission. Adult Ae. aegypti and Ae. albopictus were orally infected with the MAYV strains, and the infection, dissemination, and transmission rates were calculated to evaluate their vector competence. Overall, we found higher infection, dissemination, and transmission rates in both Ae. aegypti and Ae. albopictus mosquitoes infected with the strain isolated during a MAYV outbreak, whereas low/no transmission was detected with the strain isolated during a year of low MAYV activity. Our results confirmed that both Ae. aegypti and Ae. albopictus are competent vectors for the emergent MAYV. Our data suggest that strains isolated during MAYV outbreaks might be better fit to infect and be transmitted by urban vectors, raising serious concern about the epidemic potential of MAYV.