bunyavirus

bunyavirus, any virus belonging to the class Bunyaviricetes. The class includes two primary orders, Elliovirales and Hareavirales, which are further subdivided into multiple families, distinguished by differences in their genomes, evolutionary relationships, and host ranges. Certain bunyaviruses are sources of disease in humans, typically being transmitted through arthropod vectors, such as mosquitoes and ticks, or through contact with rodent excreta. They frequently cause severe illness, including hemorrhagic fevers, encephalitis (brain inflammation), and renal failure, often with high mortality rates.

Genomic features

Bunyaviruses have enveloped virions (virus particles) that are about 80–120 nm (1 nm = 10⁻⁹ meter) in diameter. The nucleocapsid (consisting of a protein shell, or capsid, and viral nucleic acids) is helical and elongated. The bunyavirus genome is made up of three segments (large, medium, and small) containing single-stranded negative-sense RNA (ribonucleic acid). The genome encodes an endogenous RNA polymerase enzyme that is used to transcribe the negative-sense RNA into positive-sense RNA, which can then be used for the translation, or synthesis, of proteins.

Examples

Hantaviruses, well-characterized bunyaviruses, can cause acute respiratory illness in humans. The hantaviruses are evolutionarily adapted to a specific rodent host, and thus rodents, including rats and mice, act as viral reservoirs. Human infection occurs following unusual or intense contact with infected rodent populations. The virus is transmitted primarily through the inhalation of dust that contains dried rodent excreta.

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Schmallenberg virus causes congenital malformations and stillbirths in ruminants, including cattle and sheep. It was first isolated in 2011, when a mysterious illness characterized by diarrhea, fever, and reduced milk production struck dairy cattle in Germany. Its primary vector appears to be midges.

Cat Que virus was first isolated in 2004 from mosquitoes and children in northern Vietnam. It was later found circulating in domestic pigs in China. Cat Que virus is transmitted primarily by Culex mosquitoes, with pigs serving as a natural host. In humans the virus can cause fever and viral encephalitis.