Diversity and evolutionary analysis of viruses carried by mosquitoes in Shandong, China

ABSTRACT Arboviruses represent a growing threat to global public health, as climate change is exacerbating the spread of these vectors and thereby increasing the transmission potential of arboviruses. As primary vectors, mosquitoes harbor remarkably diverse virus populations, broadly classified into mosquito-borne viruses and mosquito-specific viruses. Although metagenomic sequencing has revolutionized viral discovery, geographical variations in mosquito viromes remain poorly characterized. In this study, we conducted comprehensive viral surveillance on 5,051 mosquitoes representing six medically important species (grouped into 14 taxonomic units) collected from Shandong, China, in 2021. Using next-generation sequencing, we generated 3.7 billion clean reads and identified 10 distinct virus species spanning eight virus families. Phylogenetic analyses revealed substantial genomic diversity and complex evolutionary relationships, including two completely novel virus species and several incompletely characterized known viruses. Notably, Culex quinquefasciatus mosquitoes exhibited significantly greater viral diversity than other species, although we observed considerable overlap in viral communities across mosquito taxa, suggesting non-host-specific viral maintenance. The presence of two novel viruses in field populations was confirmed by RT-qPCR screening, wherein minimum infection rates of 0.16% and 0.38% were established. Our findings substantially expand the known diversity of mosquito-associated viruses in East Asia and provide critical baseline data for arbovirus surveillance programs. This work highlights the value of systematic virome characterization for predicting emerging arboviral threats and understanding virus-mosquito ecology in changing environments. IMPORTANCE Ten viruses, including two novel ones, were found in a study performed on mosquitoes in Shandong, China. It shows viral diversity and coexistence in different species, highlighting host impact on viral communities. The new viruses are prevalent locally, with infection rates of 0.38% and 0.16%. This work advances viral ecology understanding and has public health significance. This study sheds light on the circulation of the identified viruses in Shandong.