Susceptibility of potential mosquito vectors to bovine ephemeral fever virus

Bovine ephemeral fever is caused by Bovine ephemeral fever virus (BEFV) that belongs to the genus Ephemerovirus of the family Rhabdoviridae. BEFV is transmitted by insect vectors and causes significant economic loses of dairy industry. Epidemiological studies implicate that insects transmit BEFV, but their identity remains unclear. The virus has been isolated from biting midges (Culicoides spp.) and mix pools of mosquitoes. Moreover, disparity between the distribution of Culicoides biting midges and BEFV transmission pattern suggest there must be several vectors involved in its transmission. Our objective was to study the susceptibility and transmission potential of two mosquito species to BEFV. The susceptibility of Culex tritaeniorhynchus and Aedes aegypti to BEFV was examined by oral infection and intrathoracic injection. BEFV was detected in the midgut of C. tritaeniorhynchus and A. aegypti by RT-PCR at 7, 10, and 14 days after oral infection. Intrathoracic injection increased the detection probability of BEFV in the midgut, salivary gland, and the rest tissues of A. aegypti, but only in the midgut and the rest tissues of C. tritaeniorhynchus. The potential of BEFV transmission by these mosquitoes was evaluated by the recovery of virus from C6/36 (mosquito) cells inoculated with saliva. The result suggests that BEFV was present in the saliva of C. tritaeniorhynchus, and mosquito bite may transmit BEFV to cattle. The study will identify the potential vectors of BEFV and help understand the vector-virus interactions on BEFV transmission.