Metagenomic Analysis of Mosquito Viromes from UK Zoos
The use of metagenomics to assess viral populations in mosquitoes has expanded in recent decades, enabling the detection of both arboviruses and insect-specific viruses (ISVs). While some ISVs influence traits that influence vectorial capacity,   early arbovirus detection is crucial for mitigating public and animal health risks. Although mosquito virome studies have been conducted in various regions worldwide, UK mosquito populations remain comparatively understudied. To address this gap, we conducted metagenomic sequencing of two important mosquito vectors, Culex pipiens s.l. and Culiseta annulata, collected at two UK locations between 2021 and 2022. A total of 3,920 mosquitoes underwent sequencing across 44 pools, leading to the identification of 26 viral genomes, including nine novel species spanning RNA and DNA virus families. Notably, two novel Orthobunyavirus species, Atherstone and Deva viruses, were detected, representing the first documented mosquito-associated members of this group in the UK. These findings expand the known diversity of orthobunyaviruses, several of which are known or suspected to be pathogenic to humans and animals. While Deva virus was detected solely at Chester Zoo, Atherstone virus was present at both zoos and was classified as a putative arbovirus by the machine-learning tool MosViR, warranting further investigation. Viral distribution patterns revealed viruses shared across all pools, supporting the possibility of a conserved virome between mosquito species. These findings enhance our understanding of UK mosquito viromes, underscore the potential risks posed by orthobunyaviruses, and highlight the value of metagenomic surveillance for detecting emerging viral threats.