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Hepatitis C virus genotypes
Last reviewed: 07.07.2025
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There are 6 genotypes and 11 major subtypes of the hepatitis C virus. Genotype 1, particularly 1b, causes more severe disease and is the most resistant to treatment. It usually has higher levels of viremia. Based on the genetic heterogeneity of HCV strains, it has been suggested that the divergence of HCV genotypes occurred approximately 300 years ago.
[ Prevalence of Hepatitis C Virus Genotypes in the World
Genotypes of НСV are distributed unevenly. Thus, genotypes 1, 2, 3 are widespread. Genotypes 1 and 2 prevail in Western Europe and the Far East (except Thailand). In the USA, genotypes 1a and 1b are most common, while 2a, 2b, 3a are rare. Genotype 4 is widespread in Africa, and is dominant in Egypt and Zaire. Genotype 5 prevails in South Africa. Genotype 6 is detected most often in Asia. In Japan, genotype 1a occurs in 1%, 1b - in 74, 2a - in 18, 2b - in 6% of patients with chronic hepatitis C, coinfection 1b + 2a - in 1% of them.
The distribution of hepatitis C virus genotypes among patients with somatic pathology (hemophilia, hemoblastoses, malignant solid tumors), patients of hemodialysis departments, etc. is largely determined by the area of residence - the majority are patients with the НСV genotype, the most common in this area. However, at present, given the wide international connections, this situation may change in some regions.
The predominant genotype of the hepatitis C virus in Japan is 1b. However, Japanese patients with hemophilia annually receive a significant amount of blood products from the United States, where genotype 1a currently remains predominant. By 1996, more than 1/3 of HCV-infected hemophiliacs in Japan had genotype 1a, while in the Japanese population as a whole its prevalence barely exceeds 1% of all HCV-infected patients.
In adult hematological patients in Russia, genotype 1b predominates (51.8% of cases), followed in descending order by frequency by genotypes 3a - 22.8%, 1a - 3.6%, 2 - 2.4%, a mixture of genotypes - 1.2%; non-typable - 18.1%; in the group of chronic НСV carriers: 1b - 63.2%, 3a - 21%, 1a - 0%, 2 - 5.3%, non-typable - 10.5%, a mixture of genotypes is not detected.
The overall distribution of hepatitis C virus genotypes in 2006 was as follows: in the group of hematological patients: 1b - 35.6%, 3a - 22%, 1a - 4%, 2 - 5.9%, a mixture of genotypes - 5.3%; non-typable - 27.2%, in patients without hematological pathology: 1b - 33.3%, 3a - 32.05%, 1a - 2.6%, 2 - 10.25%, a mixture of genotypes - 5.1%; non-typable - 16.7%. Both groups of patients are characterized by a 1.5-fold decrease in the percentage of genotype 1b compared to 2003. Data for 2004-2006 on the percentage of genotypes for the group of hematological patients show: the proportion of genotype 3a has not changed; 2 - smoothly increased from 2.4 to 8.35%; 1a - after a twofold increase in 2004, decreased to 2.5% by 2006. By 2006, a noticeable increase in the proportion of a mixture of genotypes was observed - up to 8.35%, with genotype 1a present in most mixtures. Data for 2004-2006, in the second group, the proportion of genotype 3a increases from 21 to 42%; genotype 2 - sharply increases to 17.2% in 2004 and gradually decreases to 3.3%; a low level of genotype 1a (3-4%) remained. Both groups of patients are characterized by a significant increase (up to 30%) in the proportion of non-typable НСV variants in 2005 and its decrease in 2006.
There is a correlation between the genotype of the hepatitis C virus and the route of infection. Genotype 1b is found in more than 80% of HCV-infected patients who received blood products, while in НСV-infected drug addicts it is found only in isolated cases, and genotype 3a predominates in them.
The most frequently detected genotype among Russian children with chronic hepatitis C, occurring against the background of severe somatic pathology, is genotype 1b, detected in more than 25%. Genotypes 5 and 6 were not detected. Genotype 1a was detected in 9.6%, 2a - in 12.2%, 2b and 3a - in 9.6%, 3b - in 6.1%, 4 - in 18.2% of children.
The blood serum of 8.6% of patients is positive for two genotypes simultaneously. Although the hepatitis C virus is largely capable of mutations, given that the nucleotide sequences of conservative regions of the НСV genome were used to create the primers for genotyping, the detection of several genotypes in one patient may indicate repeated infection with the hepatitis C virus during treatment of a somatic disease.
In general, the distribution of hepatitis C virus genotypes among children with somatic pathology does not differ fundamentally from the prevalence of НСV genotypes both in the European region and in Russian children with an uncomplicated premorbid background.
When comparing the prevalence of hepatitis C virus genotypes among children with various somatic pathologies, no statistically significant differences were found. Apparently, both the presence of a common donor blood bank and the formation of "horizontal" transmission routes in a somatic hospital play a role here.