Hepatitis

Serological tests detecting specific antibodies and antigens using ELISA and micro-EIA are adequate for the primary diagnosis of hepatitis A, B, C and E viruses (HAV, HBV, HCV and HEV). The detection of HCV RNA is a very useful complement to the standard screening and confirmation test (RIBA) to establish the diagnosis of hepatitis C. In particular, the reverse PCR is useful for the testing of the newborn with maternal anti-HCV antibodies. Detection of HCV RNA in donor blood or in pools of donor blood is implemented in many cases. However, the most important role of real-time PCR and other nucleic acid-based tests for hepatitis C and B viruses relates to therapy. Commercial HCV reverse PCR tests come in both qualitative and quantitative versions.
Before PEG-interferon a–ribavirin therapy is attempted against hepatitis C, an anti-HCV positive patient should in addition test positive in the HCV RNA qualitative test. The next step is then to perform a quantitative reverse PCR-test to establish the HCV RNA in IUmL^-1 serum. The amplification product is employed in a line probe assay in
order to determine the genotype . Different genotypes require different lengths of treatment and the quantitative reverse PCR test is used at intervals to monitor the response to treatment and the result may decide whether therapy is successful and should be completed or not.
When therapy is completed, the HCV PCR test is used to make sure that HCV does not relapse in the next 6 months and that a sustained viral response has occurred.
Antiviral treatment is also attempted in hepatitis B in order to prevent accelerating damage to the liver and quantitative PCR to determine viral load in serum prior and during treatment is important. Only occasionally is HBV eradicated as a result of treatment. Instead, drug-resistant mutants commonly develop and are associated with specific point mutations that can be determined by DNA sequencing.