Culex saltanensis and Culex interfor (Diptera: Culicidae) are susceptible and competent to transmit St. Louis encephalitis virus (Flavivirus: Flaviviridae) in central Argentina.

Infectious diseases caused by mosquito-borne viruses constitute health and economic problems worldwide. St. Louis encephalitis virus (SLEV) is endemic and autochthonous in the American continent. Culex pipiens quinquefasciatus is the primary urban vector of SLEV; however, Culex interfor and Culex saltanensis have also been found naturally infected with the virus, suggesting their potential role as vectors. OBJECTIVE: The aim of this study was to determine the vector competence of Cx. interfor and Cx. saltanensis for SLEV from central Argentina in comparison to Cx. p. quinquefasciatus. METHODS: Adult female mosquitoes of the three Culex species were orally infected by feeding on viremic chicks that had been inoculated with SLEV. Then, abdomens, legs and saliva blood-fed mosquitoes were analyzed by viral plaque assay and the presence of cytopathic effect on the cell culture monolayer. RESULTS: Mosquitoes were permissive to orally acquired infections, to virus dissemination, and transmission of SLEV in the saliva. Cx. saltanensis and Cx. interfor are potential vectors of SLEV. CONCLUSIONS: Our results demonstrate that in Argentina both Cx. saltanensis and Cx. interfor are susceptible to SLEV and competent for its transmission. Moreover they are abundant during SLEV epidemic period in urban area, positive for this virus in nature, and found to feed on natural hosts.