what is Hepatitis c genotype
Hepatitis C (HCV) genotypes are different types of the HCV virus, which evolved over hundreds of years. The major genotypes branched off from an ancestral virus about 300-400 years ago.
In the genetic code, all HCV genotypes have the same parts. However, when the original genotype changes, some differences appear in certain parts of the genetic code. Different genotypes appear in different parts of the world. These differences arise as viruses adapt to different environments and challenges.
In our bodies, HCV multiplies (replicates) very quickly, creating more than a trillion virus seeds every day. Many of these new viruses are different from the original viruses; these different versions are referred to as mutants. Most of these mutants cannot survive. However, there are some who survive, even when the anti-HCV drugs are used. These mutants have only minor differences in the HCV genetic code, and are not considered a new genotype.
HCV has six genotypes and labeled from 1 to 6. There are also subtypes labeled with letters, for example genotypes 1a and 1b. Most people are infected with one dominant genotype, but it is possible to be infected with more than one genotype at once (combined infection).
what is the importance of knowing hcv genotype?
At the start of Hepatitis C treatment, information regarding HCV genotype is important information that can help patients and doctors find the most effective treatment.
All HCV genotypes cause the same amount of liver damage. However, people infected with genotype 1, particularly subtype 1b, may have a greater chance of developing cirrhosis, or severe liver scarring, than other genotypes. Genotypes 1b and 3 can also increase the risk of liver cancer.
Currently, the latest Hepatitis C treatments (including those used in Indonesia) are pan-genotypic. Pan-genotypic means it can cure all genotypes. Therefore, Hepatitis C genotype testing is rarely done in Indonesia as a prerequisite for starting treatment. Most HCV genotype tests are performed for survey or study purposes.
Due to the diversity of HCV genotypes, this makes it difficult to develop a Hepatitis C vaccine because an effective vaccine should elicit immune responses to all HCV genotypes.
Genotype and Steatosis (fatty liver disease)
Steatosis (fatty liver) is a common problem associated with HCV infection.
Steatosis may influence disease progression and response to HCV treatment although the exact mechanisms are not completely understood. People with HCV genotype 3 are more likely to develop steatosis and it is thought that HCV genotype 3 is a risk factor in its own right and may actually play a direct role in the development of steatosis. It has been reported that when treated successfully for HCV genotype 3, the steatosis generally improves and the steatosis can reverse.
WHICH part of the world are HCV GENOTYPES FOUND?
- Genotypes 1, 2, and 3 are commonly found throughout the world. Subtypes 1a and 1b are the most common, and cause approximately 60-70% of HCV infections worldwide. Subtype 1a is mainly found in North America, South America, Europe and Australia. Subtype 1b is found in North America, Europe, and parts of Asia.
- Genotype 2 is found in most developed countries, but is much less common than genotype 1.
- Genotype 3 mostly found in South-East Asia and other places as well
- Genotype 4 mostly found in Middle-East, Egypt and Central Africa
- Genotype 5 is found in local clusters throughout the world, but the number of people infected with it overall is relatively small.
- Genotype 6 is found in Asia.
How is Genotype Determined?
Blood samples infected with HCV are tested to determine the genetic sequence of the virus. The HCV genotype test is only done once because the genotype does not change. However, after recovery (either with treatment or self-recovery), we can be reinfected with a different HCV genotype.