Multiplication of bluetongue virus in Culicoides nubeculosus (Meigen) simultaneously infected with the virus and the microfilariae of Onchocerca cervicalis (Railliet & Henry)

Abstract

Culicoides nubeculosus under normal experimental conditions was found incapable of supporting multiplication of bluetongue virus (BTV) after infection via the oral route. Simultaneous infection with BTV and the microfilariae of Onchocerca cervicalis, a filarial worm of the horse, transformed this situation. A small proportion of infected midges subsequently developed high titres of virus, which persisted until the termination of the experiment at day 13 post infection. C. nubeculosus intrathoracically inoculated with BTV were found to transmit the virus after 7, 8 and 14 days incubation at 26°C, with no evidence for a ‘salivary gland barrier’. It is therefore suggested that C. nubeculosus can act as a vector of BTV when simultaneously infected with virus and the microfilariae of a filarial worm.