The transmission ecology of Tahyna orthobunyavirus in Austria as revealed by longitudinal mosquito sampling and blood meal analysis in foodplain habitats
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Background: Tahyna orthobunyavirus (TAHV) is a mosquito-borne virus that may cause mild fu-like symptoms or neurological symptoms in humans. It is historically associated with foodplain habitats in Central Europe, and the mammalophilic foodwater mosquito, Aedes vexans, is thought to be the principal vector. There are few contemporary reports of TAHV transmission ecology within mosquitoes or their vertebrate hosts, and virus infections are rarely reported (and probably seldom diagnosed). The objectives of this study were to survey the mosquito population for TAHV in three foodwater habitats and describe host usage by the predominant foodwater mosquito species to potentially defne TAHV transmission at these foci. Methods: We performed longitudinal mosquito sampling along three major rivers in eastern Austria to characterize the mosquito community in foodplain habitats, and tested for the presence of TAHV in pools of mosquitoes. We characterized TAHV rescued from mosquito pool homogenate by sequencing. We surveyed mosquito host selection by analyzing mosquito blood meals. Results: We identifed TAHV in two pools of Ae. vexans captured along the Leitha River. This mosquito, and other foodwater mosquitoes, used large mammals (red deer, roe deer, wild boar) as their hosts. The sequence of the rescued virus was remarkably similar to other TAHV isolates from the region, dating back to the frst isolate of TAHV in 1958. Conclusions: In general, we confrmed that TAHV is most likely being transmitted by Ae. vexans, although the precise contribution of vertebrate-amplifying hosts to the ecological maintenance of the virus is unclear. The pattern of host selection matches the estimated exposure of the same large mammal species in the region to TAHV based on a recent serosurvey, but hares were also hosts at the site where TAHV was detected. We also confrm humans as hosts of two foodwater mosquito species, providing a potential mechanism for spillover of TAHV or other mosquito-borne viruses.