Basis of hepatitis delta virus disease?
Article Abstract:
Viroids are evolutionary precursors of viruses which contain small molecules of RNA (ribonucleic acid), a source of genetic information. Viroids must rely on the mechanisms of the host for replication as they contain no mechanisms of their own. Viroids are found primarily in plants. Recently it has been shown that these viroids are similar to a component of the host, the signal recognition particle involved in the passage of protein molecules through or onto a cell membrane surface. It is thought that the viroid and the signal recognition particle may form complexes which inhibit the signal recognition particle from functioning properly and may be a factor in disease. Hepatitis delta virus causes severe liver disease in humans. Hepatitis, inflammation of the liver, is characterized by jaundice or yellowing of the skin, swelling of the liver, liver dysfunction, abdominal and gastric discomfort and may lead to cirrhosis, or degeneration of the liver cells and chronic liver dysfunction. Hepatitis delta virus was shown to contain RNA sequences that are similar to the RNA of the human signal recognition particle. The virus and the signal recognition particle may form complexes that do not allow the signal recognition particle to function properly, resulting in death of the cells that contain the virus. This hypothesis needs to be tested experimentally, but may lead to new therapies in the treatment of delta hepatitis.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1989
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New tool for Swiss army knife
Article Abstract:
Viruses are tiny and have limited genetic material, but have to successfully take over larger cells. They have evolved to carry weapons such as the helper component protease (HC-Pro). HC-Pro was identified as a protease cleaving viral polyproteins into functional subunits but it also binds RNA and has a role in amplification of the viral RNA genome, and can paralyze plant defence mechanisms. The mechanism, based on post transcriptional gene silencing (PTGS) was initially seen in transgenic plants.Anandalakshmi and colleages, Brigneti and colleagues and Kasschau and Carrington have demonstrated the suppression of the PTGS response when the HC-Pro protein of tobacco etch virus and protein 2b of cucumber mosaic virus are expressed in tobacco.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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Moving targets
Article Abstract:
Research describing the working of 'RNA silencing' in plants and the strategies used by viruses to fight this silencing response are discussed. A model is provided for how RNA silencing operates.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2000
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