Metagenomic analysis of individual mosquito viromes reveals the geographical patterns and drivers of viral diversity.

Mosquito transmitted viruses are responsible for an increasing burden of human disease. Despite this, little is known about the diversity and ecology of viruses within individual mosquito hosts. Here, using a meta-transcriptomic approach, we determined the viromes of 2,438 individual mosquitoes (81 species), spanning ~4,000 km along latitudes and longitudes in China. From these data we identified 393 viral species associated with mosquitoes, including 7 (putative) species of arthropod-borne viruses (that is, arboviruses). We identified potential mosquito species and geographic hotspots of viral diversity and arbovirus occurrence, and demonstrated that the composition of individual mosquito viromes was strongly associated with host phylogeny. Our data revealed a large number of viruses shared among mosquito species or genera, enhancing our understanding of the host specificity of insect-associated viruses. We also detected multiple virus species that were widespread throughout the country, perhaps reflecting long-distance mosquito dispersal. Together, these results greatly expand the known mosquito virome, linked viral diversity at the scale of individual insects to that at a country-wide scale, and offered unique insights into the biogeography and diversity of viruses in insect vectors.

Hemorrhagic fever caused by a novel tick-borne Bunyavirus in Huaiyangshan,China / 中华流行病学杂志

Background:From April to July in 2009 and 2010,unexplained severe hemorrhagic fever-like illnesses occurred in farmers from the Huaiyangshan mountains range.Methods:Clinical specimens (blood,urine,feces,and throat swabs) from suspected patients were obtained and stored.Mosquitoes and ticks in affected regions were collected.Virus was isolated from 2 patients and characterized by whole genome sequencing.Virus detection in additional patients and arthropods was done by virus-specific reverse transcription (RT) PCR.Clinical and epidemiological data of RT-PCR confirmed patients were analyzed.Results:An unknown virus was isolated from blood of two patients and from Haemaphysalis ticks collected from dogs.Whole genome sequence analysis identified the virus as a novel member of the family Bunyaviridae,most closely related to the viruses of the genus Phlebovirus within which it forms a separate lineage.Subsequently,infection was confirmed by RT-PCR in 33 of 58 suspected patients.The illness in these patients was characterized by fever,severe malaise,nausea,vomiting,and diarrhea.Prominent laboratory findings included low white cell- and platelet counts,coagulation disturbances,and elevation of liver enzymes.Hemorrhagic complications were observed in 3 cases,5 (15%) patients died.Conclusions:A novel tick-borne Bunyavirus causing life-threatening hemorrhagic fever in humans has emerged in the Huaiyangshan mountain areas of China.Further studies are needed to determine the epidemiology,geographic distribution and vertebrate animal ecology of this virus.