Diagnostic Molecular Pathology, 2nd Edition - Chapter 6: Molecular testing in hepatitis virus-related disease

Infections with hepatitis viruses remain major causes of life-threatening liver diseases, including acute hepatic failure, chronic hepatitis, cirrhosis, and primary hepatocellular carcinoma. Estimates indicate that more than half a billion people are symptomatically infected by one or more of the five main hepatitis viruses, namely hepatitis A, B, C, D, and E. Hepatitis B virus and hepatitis C virus are responsible for 96% of all hepatitis mortality, while the total mortality due to viral hepatitis was 1.34 million based on the World Health Organization’s estimation for 2015. This number of deaths is higher than that caused by HIV or malaria and comparable to that resulting from tuberculosis. Detection of viral proteins and/or respective antibodies in serum or plasma remains important but is not always sufficient to diagnose infection and its resolution, or to monitor progression and outcomes of antiviral therapy. Sensitive molecular assays, based predominantly on the polymerase chain reaction, became clinically necessary for virus detection, quantification, genotyping, and identification of drug-resistant variants in the era of increased availability of highly effective antiviral treatments. Application of molecular tests also contributed to our better understanding of natural history of infections caused by these viruses, uncovered asymptomatic persistence of some of them, and expanded their pathogenic relevance to diseases beyond the liver. This overview summarizes the current molecular methods of detection and quantification of hepatitis virus genomes, with special emphasis on the assays commercially available and applicable for clinical use.