Transmission studies of a European XXXX in the floodwater mosquito Aedes vexans (Diptera: Culicidae).

@entity1 @entity221 @entity281 @entity291 @entity12385
Sindbis viruses are arthropod-borne viruses, which are maintained in nature in a Culex mosquito-bird associated transmission cycle, but Aedes species have been suspected as playing a role in infecting @entity1 . In this study, we addressed the question whether or not Germany's most abundant floodwater mosquito species Aedes vexans (Diptera, Culicidae) can serve as an efficient vector for Sindbis viruses. Firstly, the overall susceptibility of Ae. vexans was tested by intrathoracic inoculation of 40 plaque forming units (PFU) @entity221 ( @entity221 , an European @entity12385 isolate) per female mosquito. Viral titres rose after inoculation reaching a maximum (about a 350-fold increase) between days 5 and 7. Throughout the three weeks of the experiment, virus was recovered from 85% of the individuals demonstrating that Ae. vexans became persistently infected with @entity221 . @entity281 studies were performed using @entity221 -spiked @entity291 blood and an artificial feeding device mimicking viremic animals with @entity221 titres between 3.7 x 10(6) and 1.3 x 10(7) PFU/ml. The bodies and legs of the mosquitoes were investigated separately. One week after @entity281 , 1 out of 49, and another week later, none of the 36 mosquitoes harboured detectable virus. None of the legs yielded detectable virus at any point in time, indicating that no disseminated @entity281 took place after oral uptake of the virus. Virus titres at 12 and 24 hours after the infectious blood meal were found to directly correspond to the amount of blood meal remaining in the midgut of engorged mosquitoes. Within 24 hours, 50% of the mosquitoes have apparently digested and excreted the blood and no virus could be re-isolated. Interestingly, virus could be recqvered from the faeces of these mosquitoes, collected from the bottom of the cage at 24 hours after feeding. In conclusion, the strain of German Ae. vexans used in this study was found to be refractory to @entity221 because of a midgut @entity281 barrier. Thus, we assume that in a scenario in which @entity12385 viremic birds travel through and roost in Germany during their migration, Ae. vexans would probably not play a role either as a bridge vector for @entity1 @entity281 or in establishing a natural transmission cycle in Germany.
