Hepatitis C virus: Difference between revisions
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{{Taxobox_begin | color = violet | name = ''Hepatitis C virus''}} |
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{{Taxobox_begin_placement_virus}} |
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{{Taxobox_group_iv_entry}} |
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{{Taxobox_familia_entry | taxon = ''[[Flaviviridae]]''}} |
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{{Taxobox_genus_entry | taxon = ''[[Hepacivirus]]''}} |
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{{Taxobox_species_entry | taxon = '''''Hepatitis C virus'''''}} |
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{{Taxobox_end_placement}} |
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{{Taxobox_end}} |
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:Hepatitis c is a bad diseas that hurts your immune system in a way that i dont know because i dont know why. For the disease, see [[Hepatitis C]].'' |
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The '''''Hepatitis C virus''''' ('''HCV''') is a small (50 [[metre#SI prefixes|nm]] in size), enveloped, single-stranded, positive sense [[RNA]] virus in the family ''[[Flaviviridae]]''. Although [[hepatitis A]], [[hepatitis B]], and hepatitis C have similar names (because they all cause liver inflammation), these are distinctly different viruses both genetically and clinically. |
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==Replication== |
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lalal i like cheese but now really who likes cheese its the nastiest thing that you could possibly immagine because. i hate everybody who likes cheese. i hate cheese particles produced each day in an infected individual. Due to lack of proofreading by the HCV RNA polymerase, HCV also has an exceptionally high mutation rate, a factor that may help it elude the host's immune response. |
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===Location=== |
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HCV mainly replicates within [[hepatocyte]]s in the liver, although there is controversial evidence for replication in [[lymphocyte]]s or [[monocyte]]s. By mechanisms of [[host tropism]], the viruses reach these proper locations. Circulating HCV particles bind to [[receptor (biochemistry)|receptors]] on the surfaces of hepatocytes and subsequently enter the cells. Two putative HCV receptors are [[CD81]] and human [[scavenger receptor class B1]] (SR-BI). However, these receptors are found throughout the body. The identification of hepatocyte-specific cofactors that determine observed HCV liver [[tropism]] are currently under investigation. |
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===Biosynthesis=== |
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Once inside the hepatocyte, HCV initiates the [[lytic cycle]]. It utilizes the intracellular machinery necessary to accomplish its own replication.<!-- |
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--><ref name="lindenbach">{{cite journal | author = Lindenbach B, Rice C | title = Unravelling hepatitis C virus replication from genome to function. | journal = Nature | volume = 436 | issue = 7053 | pages = 933-8 | year = 2005 | id = PMID 16107832}}</ref> |
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Specifically, the HCV genome is [[translation (biology)|translated]] to produce a single protein of around 3011 amino acids. This "polyprotein" is then proteolytically processed by viral and cellular [[proteases]] to produce three structural (virion-associated) and seven nonstructural (NS) proteins. Alternatively, a frameshift may occur in the Core region to produce an Alternate Reading Frame Protein (ARFP). HCV encodes two proteases, the NS2 cysteine autoprotease and the NS3-4A serine protease. The NS proteins then recruit the viral genome into an RNA replication complex, which is associated with rearranged cytoplasmic membranes. RNA replication takes places via the viral RNA-dependent [[RNA polymerase]] of NS5B, which produces a negative-strand RNA intermediate. The negative strand RNA then serves as a template for the production of new positive-strand viral genomes. Nascent genomes can then be translated, further replicated, or packaged within new virus particles. New virus particles presumably bud into the secretory pathway and are released at the cell surface. |
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==Types== |
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Based on genetic differences between HCV isolates, the hepatitis C virus species is classified into six [[genotypes]] (1-6) with several subtypes within each genotype. Subtypes are further broken down into quasispecies based on their genetic diversity. The preponderance and distribution of HCV genotypes varies globally. For example, in [[North America]], genotype 1a predominates followed by 1b, 2a, 2b, and 3a. In [[Europe]], genotype 1b is predominant followed by 2a, 2b, 2c, and 3a. Genotypes 4 and 5 are found almost exclusively in [[Africa]]. Genotype is clinically important in determining potential response to [[interferon]]-based therapy and the required duration of such therapy. Genotypes 1 and 4 are less responsive to [[interferon]]-based treatment than are the other genotypes (2, 3, 5 and 6).<!-- |
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--><ref name="simmonds">{{cite journal | author = Simmonds P, Bukh J, Combet C, Deléage G, Enomoto N, Feinstone S, Halfon P, Inchauspé G, Kuiken C, Maertens G, Mizokami M, Murphy D, Okamoto H, Pawlotsky J, Penin F, Sablon E, Shin-I T, Stuyver L, Thiel H, Viazov S, Weiner A, Widell A | title = Consensus proposals for a unified system of nomenclature of hepatitis C virus genotypes. | journal = Hepatology | volume = 42 | issue = 4 | pages = 962-73 | year = 2005 | id = PMID 16149085}}</ref> |
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Duration of standard interferon-based therapy for genotypes 1 and 4 is 48 weeks, whereas treatment for genotypes 2 and 3 is completed in 24 weeks. |
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==Vaccination== |
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Unlike hepatitis A and B, there is no [[vaccine]] to prevent hepatitis C infection. |
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In a [[2006]] study, 60 patients received four different doses of an experimental hepatitis C vaccine. All the patients produced antibodies that the researchers believe could protect them from the virus.<!-- |
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--><ref name="KGO-TV-HepcVaccine">{{cite news | first=Dean | last=Edell | url=http://abclocal.go.com/kgo/story?section=edell&id=4278043 | title=Hepatitis C Vaccine Looks Promising | publisher=ABC7/KGO-TV | date =2006 | accessdate =2006-07-04}}</ref> |
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==Current Research== |
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In 2007 the World Community Grid launched a project where by computer modeling of the Hepatitis C Virus (and related viruses) thousands of small molecules are screened for their potential anti-viral properties in fighting the Hepatitis C Virus. This is the first project to seek out medicines to directly attack the virus once a person is infected. This is a distributed process project similar to [[SETI@Home]] where the general public downloads the World Community Grid agent and the program (along with thousands of other users) screens thousands of molecules while their computer would be otherwise idle. If the user needs to use the computer the program sleeps. There are several different projects running, including a similar one screening for anti-AIDS drugs. The project covering the Hepatitis C Virus is called "Discovering Dengue Drugs – Together." The software and information about the project can be found at: |
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*[http://www.worldcommunitygrid.org World Community Grid web site] |
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==References== |
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<references/> |
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== External links == |
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* [http://www.liverfoundation.org American Liver Foundation: Comprehensive information about Hepatitis C, including links to chapters for finding local resources] |
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[[Category:Flaviviruses]] |
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[[ja:C型肝炎ウイルス]] |
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[[fr:Virus de l'hépatite C]] |
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