Low Generation Culex quinquefasciatus from Texas and Culex pipiens from New Jersey Are Incompetent Vectors for Oropouche Virus.

During the 2024 Oropouche virus (OROV) outbreak in South America, mosquito surveillance led to the identification of pools of Culex quinquefasciatus infected with the virus. Because of the outbreak strain's status as a novel reassortment and the novel sequela discovered during this outbreak, concerns arose about Culex species as potential vectors in the continental United States. To assess the risk posed by Cx. quinquefasciatus and the closely related species Culex pipiens, the vector competence of mosquitoes reared from eggs collected in Dallas, TX, and New Jersey was examined. Three replicates of an infectious bloodmeal were offered to Cx. quinquefasciatus at generations F2, F4, and F9, resulting in 0/305 individuals with midgut infections. One infectious bloodmeal was offered to Cx. pipiens at generation F4, with 0/120 resulting midgut infections. These data, which align with other recent publications, indicate that United States populations of Cx. quinquefasciatus and Cx. pipiens are not competent vectors of the outbreak strain of OROV.