Transmission potential of Culex and Aedes species for Madariaga virus, a member of the eastern equine encephalitis virus complex

Madariaga virus (MADV), widely distributed in Latin America, can cause severe disease in humans and equids, yet key aspects of its transmission cycle remain unclear. To identify mosquitoes that could act as vectors of MADV, we assessed the vector competence of Aedes aegypti, Ae. albopictus, Ae. taeniorhynchus, Culex tarsalis, Cx. coronator, and Cx. quinquefasciatus, following oral exposure to MADV isolated in Panama (all species) or Brazil (Ae. taeniorhynchus only). We also evaluated temporal infection dynamics of MADV from Panama in Ae. aegypti and Ae. albopictus. MADV RNA and infectious virus were quantified in mosquito bodies, legs, and saliva. At 14 days post-exposure, five of the six species tested had virus detected in all biological sample types, indicating their potential to become infected with and transmit MADV. Conversely, Cx. quinquefasciatus was susceptible to midgut infection and dissemination but had no positive saliva samples, suggesting limited transmission potential. Aedes taeniorhynchus showed higher infection probabilities with MADV from Brazil compared with MADV from Panama. Time-course analysis revealed distinct infection dynamics in Ae. aegypti and Ae. albopictus, with infection increasing over time in Ae. aegypti, but peaking at 7 days post-exposure and then gradually declining in Ae. albopictus. Our findings indicate that MADV may be compatible with multiple mosquito species with broad geographic distributions, reinforce the need to investigate species- and strain-specific mosquito-virus interactions and their influence on arbovirus transmission dynamics, and support a potential role for Ae. taeniorhynchus as an amplification and bridge vector in endemic regions.