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]