A new duck Tembusu-related flavivirus, Baiyangdian virus (BYDV), caused duck egg-drop syndrome in China. The rapid spread, unknown transmission routes, and zoonotic nature, raise serious concern about BYDV as a potential threat to human health. The study provides the first evaluation on the vector competence of Culex and Aedes mosquitoes to transmit BYDV in China. The results show that Culex tritaeniorhynchus, Culex pipiens pallens, Culex pipiens quinquefasciatus, and Aedes albopictus can become infected with BYD-1 virus (BYDV-1) on different days after oral infection. Although the viral copies in Ae. albopictus was higher than that in Cx. p. quinquefasciatus at 13 days postinfection (χ2 = 10.385, p = 0.016), there was no significant differences between infection rates of four mosquito species (χ2 = 3.98, p = 0.137). In transmission experiment, healthy ducks were infected after being bitten by virus-positive mosquitoes and BYDV-1 disseminated to and replicated in the duck brains. These findings verified the potential role of Cx. p. quinquefasciatus and Cx. tritaeniorhynchus as vectors of BYDV-1. BYDV-1 was also detected in salivary gland of Cx. p. pallens, which indicated that this virus could be transmitted by mosquitoes. These results provide evidence for the role of Culex mosquitoes in the transmission cycles involving BYDV-1 and avian hosts in China.
Keywords: BYDV-1; Culex; vector competence.