HCV genotypes

Hepatitis C virus (HCV) genotypes refer to the genetic variations that occurs in the hepatitis C virus. Hepatitis C is a contagious disease that primarily affects the liver, causing severe damage as the disease progresses.[1] It is caused by the Hepatitis C virus, a small, enveloped RNA virus. The transmission of hepatitis C is through the contact with the blood of the infected person, for example by sharing the needles or by using non-sterile medical equipment.[2] HCV is transmitted globally because of the high infection rate and is also associated with a high mortality rate.[3][4] The World Health Organization indicates the 3.3% of the world population is infected by the HCV virus.[5] Statistical records show that there are about 13 million HCV affected persons in Сhina, 3.5 million affected persons in the United States,[6] and about 10 million people are affected by HCV in Pakistan.[3] In all cases, the viral genotype of the HCV stays the same, occasionally mutations do occur making the treatment more complex by targeting the changes in the genotype.[7] Hepatitis C virus genotype is considered more common than the Hepatitis B virus infection contributing to more than a million cases annually[8] and is considered one of the major reason for liver transplantation in United States.[9] Some of the HCV genotypes may develop in people without symptoms leading to dangerous conditions like liver cirrhosis causing a permanent damage to liver and the unnoticed HCV conditions will affect brain, joints, blood vessels, bones, and kidneys.[10]

The complexity of the HCV genotypes made the treatment specific for the associated genotype. The treatment for the HCV genotype also depends on the presence or absence of cirrhosis.[11] There are six major genotypes of hepatitis C virus which includes many subtypes.[12] The genotype can affect treatment of HCV infections.[3] Recent studies show that HCV genotypes consist of 7 genotypes and 67 subtypes.[13] All the genotypes and subtypes affect the liver to the same extent of damage irrespective of the HCV genotype[7] Among the common six genotypes, genotype 1 is the most prevalent form in the United States of America,[14] covering around 70-90% of total infections. It is usually difficult to treat the people with HCV genotype 1. Genotype 2 and genotype 3 are less common contributing to around 10-20%.[14] Genotypes 4 and 5 affect a large proportion of the population in undeveloped countries.[15] Genotype 4 is the most common type of infections in Middle East and Africa, around 80% of total infections.[16] About 15% of the people affected by HCV genotypes will get cured without medications, in which immune system plays a vital role in defeating the virus.[17] Until recently, there were no specific vaccines available for treating hepatitis C virus genotypes.[18]

Geographical distribution

People traveling around different subcontinents where several HCV genotypes are common will have the possibility of resulting in mixed infection.[7]

Geographical distribution of HCV subtypes
HCV genotypesSubsetsGeographical distribution[19]
Genotype 11a, 1bNorth America, Central Africa, Europe
Genotype 22a, 2b, 2c, 2dWestern Africa
Genotype 33a, 3b, 3c, 3d, 3e, 3fSoutheast Asia
Genotype 44a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i, 4jCentral Africa
Genotype 55aSouth Africa and Asia
Genotype 66aSoutheast Asia

Techniques

The Main techniques used to diagnose the HCV genotype are as follows:[16]

  • HCV ELISA (Enzyme-linked immunosorbent assay)
  • Quantitative HCV-RNA PCR (Hepatitis C virus-Ribonucleic acid Polymerase Chain reaction)
  • Recombinant immunoblot assay

References

  1. Available at http://www.harvoni.com/education
  2. Available at https://www.cdc.gov/hepatitis/hcv/
  3. Athar MA, Xu Y, Xie X, Xu Z, Ahmad V, Hayder Z, Hussain SS, Liao Y, Li Q (2015). "Rapid detection of HCV genotyping 1a, 1b, 2a, 3a, 3b and 6a in a single reaction using two-melting temperature codes by a real-time PCR-based assay". Journal of Virological Methods. 222: 85–90. doi:10.1016/j.jviromet.2015.05.013. PMID 26068393.
  4. Teimourpour R, Tajani AS, Askari VR, Rostami S, Meshkat Z (2016). "Designing and Development of a DNA Vaccine Based On Structural Proteins of Hepatitis C Virus". Iranian Journal of Pathology. 11 (3): 222–230. PMC 5079455. PMID 27799971.
  5. Lavanchy D (2009). "The global burden of hepatitis C". Liver International. 29 Suppl 1: 74–81. doi:10.1111/j.1478-3231.2008.01934.x. PMID 19207969.
  6. Available at http://www.medicinenet.com/hepatitis_c/article.htm
  7. Treatment action group website. Available at http://www.treatmentactiongroup.org/hcv/factsheets/hcv-genotypes
  8. Cooreman MP, Schoondermark-Van de Ven EM (1996). "Hepatitis C virus: biological and clinical consequences of genetic heterogeneity". Scandinavian Journal of Gastroenterology. Supplement. 218: 106–15. doi:10.3109/00365529609094740. hdl:2066/23986. PMID 8865460.
  9. Zein NN (2000). "Clinical significance of hepatitis C virus genotypes". Clinical Microbiology Reviews. 13 (2): 223–35. doi:10.1128/cmr.13.2.223-235.2000. PMC 100152. PMID 10755999.
  10. Website link for everyday life: http://www.everydayhealth.com/hs/hepatitis-c-living-well/dangers-untreated-hepatitis-c/
  11. HEP website. Available at http://hepc.liverfoundation.org/treatment/the-basics-about-hepatitis-c-treatment/medication-regimens-according-to-genotype
  12. http://www.hepatitiscentral.com/hepatitis-c/%5B%5D
  13. Smith DB, Bukh J, Kuiken C, Muerhoff AS, Rice CM, Stapleton JT, Simmonds P (2014). "Expanded classification of hepatitis C virus into 7 genotypes and 67 subtypes: updated criteria and genotype assignment web resource". Hepatology. 59 (1): 318–27. doi:10.1002/hep.26744. PMC 4063340. PMID 24115039.
  14. http://hepatitis-c.emedtv.com/hepatitis-c/hepatitis-c-genotypes.html%5B%5D
  15. Messina JP, Humphreys I, Flaxman A, Brown A, Cooke GS, Pybus OG, Barnes E (2015). "Global distribution and prevalence of hepatitis C virus genotypes". Hepatology. 61 (1): 77–87. doi:10.1002/hep.27259. PMC 4303918. PMID 25069599.
  16. Nouroz, Faisal; Shaheen, Sidra; Mujtaba, Ghulam; Noreen, Shumaila (2015). "An overview on hepatitis C virus genotypes and its control". Egyptian Journal of Medical Human Genetics. 16 (4): 291–8. doi:10.1016/j.ejmhg.2015.05.003.
  17. Hepatitis central, available at http://www.hepatitiscentral.com/hepatitis-c/
  18. Naderi M, Gholipour N, Zolfaghari MR, Moradi Binabaj M, Yegane Moghadam A, Motalleb G (2014). "Hepatitis C virus and vaccine development". International Journal of Molecular and Cellular Medicine. 3 (4): 207–15. PMC 4293608. PMID 25635247.
  19. Yu CI, Chiang BL (2010). "A new insight into hepatitis C vaccine development". Journal of Biomedicine & Biotechnology. 2010: 548280. doi:10.1155/2010/548280. PMC 2896694. PMID 20625493.
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