Vector Competence of Temperate and Tropical Mosquito Species for Babanki virus

Babanki virus (BBKV), an alphavirus belonging to the Western Equine encephalitis complex, was isolated from Mansonia africana mosquitoes in 1969 but is not characterized yet. Transmitted to humans and animals through the bite of an infectious female arthropod, it is associated with febrile illness, rash, and arthritis similarly to Sindbis virus to which it is related. No specific treatment or vaccine is available. To investigate any risk of propagation, our study investigated the vector competence of several mosquito species towards BBKV. For this purpose, laboratory mosquito colonies from metropolitan France: Culex pipiens (Paris), Aedes albopictus (Nice) as well as tropical area: Aedes albopictus (Saint-Benoit, La Reunion) and Culex quinquefasciatus (Slab strain), Aedes aegypti (PAEA) were exposed to an artificial blood meal infected with BBKV molecular clone. Midguts, legs, salivary glands and saliva were collected from individual mosquitoes of different strains or species at various time points to assess the infection status, viral replication, and infectiousness. At 7 days post viral exposure, infection rates exceeded 70% in Aedes and 40% in Culex species. They remain above 50% except for Culex quinquefasciatus which decreases to 35% at 14 days post viral exposure. Using genome and protein detection, the dissemination rates are above 50% except for Aedes albopictus (Nice) at 7 days post viral exposure. Infection assays using VeroE6 cells indicated that BBKV replicative viral particles were found in the saliva of the different populations tested. Our data demonstrate that different mosquitoes species from both temperate and tropical areas are competent to transmit BBKV suggesting an emergence risk that could trigger an outbreak in humans. Author SummaryBabanki virus (BBKV) is a non-characterized arbovirus identified in 1969 in Cameroon. BBKV is closely related to Sindbis virus which causes symptoms like febrile illness, rash, and arthritis in humans and animals. Both are alphaviruses within the Western Equine Encephalitis complex. BBKV is identified only in the African continent so far. Despite its potential to cause disease, no effective treatments are available. This study investigates the vector competence of various mosquito species from temperate and tropical regions, to transmit BBKV. After mosquitoes were fed an infectious blood meal, various organs were collected at different time points to assess the infection status, viral replication, and infectiousness. The results showed that BBKV infection occurred in all tested mosquito species and persisted over time, with viral particles detected in mosquito or that can potentially be transmitted to vertebrate hosts via mosquito saliva. These findings highlight the broad vector competence of mosquitoes from diverse climatic regions for BBKV, indicating its potential risk for emergence and outbreaks in different regions of the world. The study emphasizes the need for enhanced surveillance and preventive measures to mitigate the potential threat posed by this emerging virus.