PCR of hepatitis C

HCV in the material is normally absent.

Unlike serological methods for the diagnosis of viral hepatitis C, where antibodies to HCV are detected, PCR can detect the presence of HCV RNA directly and quantify its concentration in the test material. The test has specific specificity and high sensitivity: ten HCV RNA molecules in the test material are sufficient for its detection. Detection of antibodies to HCV confirms only the fact of infection of the patient, but does not allow to judge the activity of the infectious process (about the replication of the virus) and the prognosis of the disease. In addition, antibodies to HCV are detected both in the blood of patients with acute and chronic hepatitis, and in those patients who have been ill and recovered, and often antibodies in the blood appear only a few months after the appearance of the clinical picture of the disease, which makes diagnosis difficult. Detection of HCV in the blood using PCR is a more informative diagnostic method. The detection of HCV RNA in PCR testifies to viremia, allows to judge the replication of the virus in the body and serves as one of the criteria for the effectiveness of antiviral therapy. Detection of HCV RNA by PCR in the early stages of the development of a viral infection against the background of the complete absence of any serological markers may serve as the earliest evidence of infection. However, the isolated detection of HCV RNA against the background of the complete absence of any other serological markers can not completely eliminate the false positive result of PCR. In such cases, a comprehensive evaluation of clinical, biochemical and morphological studies is necessary, with repeated repeated confirmation of the presence of PCR infection.

Of great importance is the use of the PCR method in patients with chronic viral hepatitis C, as in most of them there is no correlation between the presence of viral replication and the activity of liver enzymes. In such cases, only PCR allows to judge the presence of viral replication, especially if the end result is expressed quantitatively. In most cases, the disappearance of HCV RNA from blood serum occurs later than the normalization of liver enzymes, so their normalization can not serve as a basis for stopping antiviral treatment.

It is practically important for the detection of HCV RNA to investigate by PCR method not only serum, but also lymphocytes, hepatobiobaptam. Viruses can be detected 2-3 times more often in liver tissue than in serum. When evaluating the results of the study of blood serum for HCV RNA, it should be remembered that viremia can be fluctuating in nature (like the change in enzyme activity). Therefore, after positive results of the PCR study, a negative result can be obtained and vice versa. In such cases, to resolve the doubts that arise, it is better to investigate hepatobiobaths.

Detection of HCV RNA in a material using PCR is used for the following purposes:

• resolution of questionable results of serological studies;
• differentiation of viral hepatitis C from other forms of hepatitis;
• the detection of the acute stage of the disease in comparison with the transferred infection or contact; the stage of infection of newborns from seropositive HCV mothers;
• monitoring the effectiveness of antiviral treatment.

Patients with suspected viral hepatitis C:

• donors;
• persons with risk factors;
• persons with increased activity of ALT;
• patients with acute hepatitis

All of the above features of evaluation of results and approaches to the diagnosis of HCV using PCR also apply to other infections.

The PCR method allows not only to detect HCV RNA in the test material, but also to establish its genotype. Determination of the genotype of the virus is of great importance for the selection of patients with chronic viral hepatitis C to conduct treatment with interferon-alpha and ribavirin. Laboratory indications for the treatment of chronic viral hepatitis C with interferon alpha are as follows:

• increased transaminase activity;
• presence of HCV RNA in the blood;
• genotype 1 of HCV;
• high viremia in the blood (more than 8 × 10 ⁵ copies / ml).

At present, HCV RNA content in blood serum can be quantitated by PCR, which is of great importance for the control of interferon alpha treatment. The level of viremia is assessed as follows: for HCV RNA from 10 ² to 10 ⁴ copies / ml - weak; from 10 ⁵ to 10 ⁷ copies / ml - medium, above 10 ⁸ copies / ml - high. With effective treatment, the level of viremia decreases.

[1], [2], [3], [4]