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finds key to easing symptoms of Ross River sulfasalazine.com |
Ross River virus (RRV) is a small encapsulated single-strand RNA alphavirus endemic to Australia, Papua New Guinea and other islands in the South Pacific. It is responsible for a type of mosquito-borne non-lethal but debilitating tropical disease known as Ross River fever, previously termed "epidemic polyarthritis". The virus is suspected to be enzootic in populations of various native Australian mammals, and has been found on occasion in horses.[1]
[edit] Classification and morphologyTaxonomically Ross River virus belongs to the virus genus Alphavirus, which is part of the family Togaviridae. The alphaviruses are a group of small enveloped single-strand positive-sense RNA viruses. RRV belongs to a subgroup of "Old World" (Eurasian-African-Australasian) alphaviruses, and is considered closely related to Sagiyama virus.[1] The virions themselves contain their genome in a protein capsid 700 Å in diameter. They are characterised by the presence of two glycoproteins (E1 and E2) embedded as trimeric dimers in a host-derived lipid envelope.[2] Because RRV is transmitted through mosquito vector it is considered an arbovirus, a non-taxonomic term for viruses borne by arthropod vectors. [edit] HistoryAn alphavirus was the prime suspect in several outbreaks of "epidemic polyarthritis" recorded in the South Pacific and Australia during the early part of the 20th century. The disease was compared to "acute viral polyarthritis" caused by Chikungunya virus, noting the Australian disease seemed to progress in milder fashion. Serological testing suggested an unknown new species of alphavirus was the likely culprit.[1] In 1959, the a new alphavirus was identified in mosquito samples trapped near Ross River, near Townsville, Queensland, Australia. Further serological testing showed that patients who had suffered "epidemic polyarthritis" in Queensland had antibodies to the virus. The new virus was named Ross River virus, and the disease Ross River fever.[1] In 1972 it was determined that RRV isoalted from human serum could kill mice. However, the serum containing the virus that was used had come from a healthy Aboriginal child. This evidence made the link between RRV and Ross River fever less concrete.[1] However RRV was later isolated in humans following a series of epidemic polyarthritis outbreaks in Fiji, Samoa and the Cook Islands, during 1979. RRV was isolated in an Australian patient suffering from Ross River fever in 1985.[1] [edit] EcologyIn rural and regional areas of Australia, the continued prevalence of Ross River virus is thought to be supported by natural reservoirs such as large marsupial mammals. Antibodies to Ross River virus have been found in a wide variety of placental and marsupial mammals, and also in a few bird species. It is not presently known what reservoir hosts support Ross River virus in metropolitan areas such as Brisbane.[1] The Southern Saltmarsh mosquito (Aedes camptorhyncus) which is known to carry the Ross River virus was discovered in New Zealand in 1998, and there is an ongoing eradication program by the New Zealand Ministry of Health, involving spraying the insectide Bti on infested areas. As of June 2007 there have been no reported cases of Ross River Virus that arose in New Zealand.[citation needed] [edit] Lab researchThe study of RRV has been recently facilited by a mouse model. Inbred mice infected with RRV develop hind-limb arthritis/arthralgia which is similar to human disease. The disease in mice, similar to humans, is characterized by an inflammatory infiltrate including macrophages which are immunopathogenic and exacerbate disease. Furthermore, recent data indicate that the serum component, C3, directly contributes to disease since mice deficient in the C3 protein do not suffer from severe disease following infection.[3] [edit] Ross River feverMain article: Ross River fever Ross River fever is also known as Ross River virus infection or Ross River virus disease. [edit] References
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