Hepatitis C virus, PCR genotyping (types 1a, 1b, 2, 3a, 4)
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Why this test?
To determine the need for treatment and predict the course of the disease;
To plan the duration of antiviral therapy and drug dosage;
To predict the effectiveness of treatment;
Making a decision about a liver biopsy.
In what cases is it prescribed?
When detecting hepatitis C virus RNA and planning antiviral therapy.
The hepatitis C virus (HCV) can infect liver cells, as well as some blood cells (neutrophils, monocytes, B-lymphocytes). Basically, the infection is transmitted through blood (preparations for transfusion of blood and plasma elements, donor organs, non-sterile syringes, needles, instruments), less likely to be sexually transmitted.
Acute viral hepatitis, as a rule, is asymptomatic and in most cases remains undetected. 60-85% of infected people develop chronic infection, which increases the risk of developing cirrhosis, liver failure and hepatocellular carcinoma. For its hidden, but destructive action, the infection received the unofficial name gentle killer.
HCV has the greatest variability among all causative agents of viral hepatitis and, thanks to its high mutational activity, is able to avoid the influence of protective mechanisms of the immune system. Genomes of the virus differ significantly in different countries of the world and have different sensitivities to interferon drugs.
There are 6 main genotypes of the hepatitis C virus and about 500 subtypes. Genotype 1 is the most common in the world (40-80%). 1a type is often found in the USA, 1b is typical for Western Europe and South Asia. Genotype 2 occurs with a frequency of 10-40%. Genotype 3 is common in Scotland, Australia, India and Pakistan. HCV type 4 is typical for Central Asia and North Africa, genotype 5 - for South Africa, 6 - for some Asian countries. In Russia, genotype 1b predominates, followed by 3, 1a, 2 in descending order of frequency, in the USA - 1a / 1b, 2b, and 3a.
Antiviral therapy aimed at suppressing the progression of the disease can, in rare cases, accelerate the development of liver complications. This happens when clinical and laboratory parameters are incorrectly assessed. RNA genotyping of the hepatitis C virus allows predicting the effect of the planned therapy.
Genotype 1 is less amenable to treatment than genotypes 2 and 3. In addition, it is more important to perform a liver biopsy in genotype 1. Increased doses of interferon drugs are recommended for patients with genotypes 1 and 4. The course of therapy in such patients should be extended to 48 weeks, even if the virus is not in the blood for more than 24 weeks. In the case of successful treatment, which is confirmed by a decrease in the viral load of the blood (<50 IU / ml in 4 weeks), a shorter duration of therapy is likely. If the number of viral copies has not decreased by 2 orders of magnitude in 12 weeks, then the treatment is ineffective and must be reviewed.
Genotypes 2 and 3 respond well to therapy in 80% of cases, usually taking 24 weeks.
The treatment is developed taking into account the gender and age of the patient, the symptoms he has, previous therapy, the structure and function of the liver, as well as laboratory indicators.