Metagenomic sequencing reveals viral diversity of mosquitoes from Egypt: co-circulation of multiple insect-specific viruses.

UNLABELLED: Mosquito-borne virus surveillance is pivotal for investigating mosquito viromes, facilitating understanding of viral evolutionary histories and genetic diversity. Natural viral communities in mosquitoes include not only insect-specific viruses (ISVs) but also viruses infecting symbiotic microorganisms. In this study, a total of 654 mosquito samples-encompassing species from the Aedes and Culex genera-were collected from Egypt and subjected to metagenomic sequencing analysis. Over 130 virus species were identified, grouped into 35 families or equivalent taxonomic ranks. Detected ISVs included Culex flavivirus (CxFV), Kustavi Toti-like virus, Hanko Toti virus 5, Culex phasma-like virus (CPLV), Culex Iflavi-like virus 1, Culex Iflavi-like virus 4, Guadeloupe Culex rhabdovirus (GCRV), and Sarawak virus, confirming concurrent ISV circulation in Egyptian mosquitoes. Phylogenetic analyses of these ISVs revealed their closest evolutionary affinities to viral genome sequences originating from the Middle East, Europe, Oceania, and Asia. Specifically, Egyptian CxFV strains exhibited a closer genetic relationship with the tropical lineage within the Latin American/Caribbean/Africa genotype. Furthermore, our study uncovered 10 putative novel viruses, which are distributed across seven viral families: Amagaviridae, Chrysoviridae, Mitoviridae, Totiviridae, Virgaviridae, Narnaviridae, and Orthomyxoviridae. Collectively, our findings emphasize the necessity for more in-depth investigations into arthropod viromes-encompassing both mosquitoes and ticks-in Egypt, as well as in neighboring African and Middle Eastern countries. Such research is critical for enhancing our understanding of viral diversity and evolutionary biology, elucidating their roles in mosquito-pathogen-host interactions, and exploring their potential as biocontrol agents against vector-borne diseases of public health importance.

IMPORTANCE: Mosquito-borne viruses are estimated to cause over 100 million human infections annually, making surveillance of these pathogens increasingly crucial amid growing international travel and trade. Egypt, situated in northeastern Africa, serves as a geopolitical and geographical hub connecting Asia, Europe, and Africa-a unique location that complicates the surveillance of mosquito-borne viruses. Arboviruses persist in nature through cyclical transmission between arthropod vectors (e.g., mosquitoes, ticks, and midges) and susceptible vertebrate hosts. Despite this, systematic investigations into mosquito viromes remain relatively scarce in Egypt. The present study aimed to explore the genetic diversity and evolutionary relationships of mosquito-associated viruses in Egypt using metaviromic sequencing. Our findings significantly expand the current knowledge of both known and previously uncharacterized mosquito-associated viruses in the region, while also providing complete genome sequences of several viruses that may infect arthropods or vertebrates, and potentially interfere with the replication of pathogenic arboviruses.