Genotypes of Hepatitis C

  • Contaminated Blood Campaign
  • The ability of the virus to mutate has resulted in the existence of 6 different genetic variations of HCV. These variations are known as 'genotypes' and are numbered from 1 to 6. The different genotypes are often, but not exclusively, related to different parts of the world.
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Genotypes of HCV

The ability of the virus to mutate has resulted in the existence of 6 different genetic variations of HCV. These variations are known as ëgenotypesí and are numbered from 1 to 6. The different genotypes are often, but not exclusively, related to different parts of the world.

Genotypes 1, 2 and 3 have a worldwide distribution. Types 1a and 1b are the most common, accounting for about 60% of global infections. They predominate in Northern Europe and North America and in Southern and Eastern Europe and Japan, respectively.

Genotype 2 is less frequently represented than type 1. Genotype 3 is endemic in south-east Asia.

Genotype 4 is principally found in the Middle East, Egypt, and central Africa. Type 5 is almost exclusively found in Africa and the Middle East.

Genotype 6 is found mainly in Southeast Asia and the latest genotype, 6, in Central Africa.

It is still unclear whether or not the type of virus effects the progression of the disease. If it does it is not thought to present of any real cause for concern. However, HCV genotype does influence the response to treatment. If you are considering treatment itís very important to know which genotype (and ideally the subtype) you are actually infected with.

Each genotype also contains as series of minor variations. These are known as ësubtypesí. They are numbered a,b,c,d etc., in order of their discovery. A person chronically infected with hepatitis C will have a viral population consisting of a very large quantity of these minor genetic variations. These are called ëquasi speciesí and present an even more complex problem for the immune system to deal with.

HCV is also described as having positive-sense, single-stranded RNA genomes. This means that each viral particle contains a single RNA strand. Within HCV the RNA has two functions. Firstly it holds the information about HCV genetics. Secondly it also contains information about how to make the proteins the virus needs for replication, both from its own components and from that of the host liver cell.

SOURCE: Hep C Trust