The main methods of hcv blood test than they differ are the indications and transcript

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2017.08.14
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Blood test

Viral hepatitis C (HCV) is a chronic liver disease that lasts for decades and, with no treatment, ends with the fatty degeneration of the body, cirrhosis and death. The virus that causes the disease is an RNA molecule placed in the viral envelope. For the reproduction of its RNA and reproduction, the virus uses the DNA of the liver cells. It is denoted by the abbreviation hcv. To determine if the body has experienced this virus, an hcv blood test is performed.

Virus in an Electron Microscope

HCV has a low antigenic activity. After entering the blood, hcv-antibodies begin to be produced in the body only after 2-3 weeks. The ineffectiveness of standard treatment and the absence of objective causes of cirrhosis make viral hepatitis C suggest, and as a result, a positive blood test for hcv is obtained as a result.

Content

  • Methods for detecting a virus
  • Indication for the study
  • Serological diagnosis
  • Features of PCR diagnostics

Methods for detecting a virus

Infection of the body with a virus triggers the mechanism of immune reactions to produce antibodies. Circulating immune complexes antigen-antibody attack inflamed hepatocytes.

On this immune mechanism, serological methods for detecting hcv infection in the body are based. Of the serological methods for the analysis on HCV, the most commonly used are immunoenzyme hcv blood test (ELISA) and radioimmunoassay (RIA). These methods are qualitative, as they allow us only to ascertain the fact that the organism was faced with HCV.

A variant of the test-marker are the rapid tests, which are designed for independent analysis of HCV.

Structure of the virus

Quantitative indices, which allow estimating the amount of RNA copies of the virus per unit volume of blood, are obtained using a polymerase chain reaction (HCV blood test PCR).

Indication for the study

Laboratory blood test hcv is performed not only with clinical indications, when the disease manifests itself in deep liver damage. An important condition for successful treatment is early diagnosis. Therefore, all people at risk are subject to examination:

  • Constant donors;
  • Patients for whom a blood transfusion procedure was applied;
  • Patients with jaundice, a prolonged increase in liver transaminases (ALT, ASAT), jaundice, if this happened after surgery, childbirth, going to the dentist, visiting the tattoo parlor.
  • With diagnostic tests to exclude viral hepatitis C, or its confirmation after a negative analysis for hepatitis B (HBsAg), or if the patient is vaccinated against the disease, and a blood test showed high titers anti-HBsAT;
  • Patients with established diagnosis of hepatitis C - to monitor the effectiveness of treatment for hcv infection.
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Important! If a person believes that he at some time was at risk of contracting hepatitis C or HIV, a month later he must go to the hospital on his own or buy an express test and do an analysis on hcv. This will protect other people from infection, and early diagnosis will make prognosis for treatment favorable.

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Serological diagnosis

HCV analysis of blood for the detection of antibodies is characterized by a high level of reliability, because several antigen complexes of different types of HCV are used as reagents. The anti-hcv method for ELISA antibodies detects immunoglobulins M and G to HCV:

  • Antibodies of class M (in the analyzes are designated as anti-HCV IgM) in isolated form show the acute (active) phase of the disease. They are produced before anti-HCV IgG, 4-6 weeks after infection;
  • G-Immunoglobulins (anti-HCV IgG assays) appear after 12 weeks and are determined in the body for several years. The presence of isolated anti-HCV IgG in blood tests shows a chronic course of the disease or indicates that the patient was once sick with HCV.
  • Detection of total antibodies Anti HCV total indicates an exacerbation of the disease, which proceeds chronically.

The breakdown of the test readings for the hcv markers can be in the form of one of four options. In addition to those described above, there may also be a negative result (hcv - negative), which means that HCV is not detected.

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Important! The detection of total antibodies is not yet a reason to believe that the virus is currently in the body. Fix fragments of viral RNA in the blood can only be done by PCR diagnostics.

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Radioimmunoassay allows to obtain quantitative characteristics of the substances sought or to confirm their absence, the number of radiolabeled molecules is measured by a radio spectrometer. But due to questionable security, this method is rarely used.

Express test

Express tests are a ready-to-use kit of reagents and a test plate, on which 2-3 drops of blood are applied. After the application of blood in the cavity it is combined with the reagent and the coloring of the indicator strips is followed. The interpretation of the results is as follows: one strip means a negative reaction, two - positive, and the absence of strips indicates a spoiled test.

Features of PCR diagnostics

Many have heard about this method, but do not know what is PCR. This method is used to detect fragments of RNA and DNA (nucleotides) of any cells, including HCV. In the presence of the desired fragment of RNA in the blood with the help of enzymes, it is duplicated several thousand times, which allows it to be detected. This method allows to obtain both qualitative and quantitative results. A qualitative result carries information on the fact of detection or absence of hcv-RNA in the blood.

The quantitative results reflect the direct number of copies of the detected fragments of viral RNA per 1 ml of blood, which is very important for determining the degree of the disease.

For the evaluation and interpretation of such results, the term "viral load" is used. At rates above 600 units of RNA copies, the viral load is considered high.

Causes, Symptoms and Diagnosis of HCV:

The definition of HCV in the body is a complex process. This is due to the length of the appearance of antibodies, the latent course of the disease. Many patients who have received a positive result on hcv, feel healthy, and the presence of the virus in the body is not manifested. It is necessary to use all available techniques to pinpoint the disease.

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