The Open Virology Journal
2013, 7 : 12-18Published online 2013 January 23. DOI: 10.2174/1874357901307010012
Publisher ID: TOVJ-7-12
RESEARCH ARTICLE
Effects of Hepatitis B Virus Mutations on its Replication and Liver Disease Severity
2 Department of Clinical Microbiology, College of Medicine, King Khalid University, Abha 61421, Saudi Arabia
* Address correspondence to this author at the Department of Medical Laboratory Sciences, College of Applied Medical Sciences, King Khalid University, P.O. Box 3665, Abha 61481, Saudi Arabia; Tel: +966-72417090 ; Fax: +966-72417746; E-mail: abdu.lightpollution@hotmail.com
ABSTRACT
Hepatitis B virus (HBV), nowadays, is one of the major human pathogens worldwide. Approximately, 400 million people worldwide have chronic HBV infection. Only 5% of persons infected during adulthood develop chronic infection. The reverse is true for those infected at birth or in early childhood, i.e. more than 90% of these persons progress to chronic infection. Currently, eight different genotypes o f HBV have been identified, differing in nucleotide sequence by greater than 8%. In addition, numerous subgenotypes have a l s o been recognized based on the nucleotide sequence variability of 4- 8%. It has invariably been found that these genotypes and mutations play a pivotal role in the liver disease aggravation and virus replication. The precore mutations (G1896A) and the double mutation (T1762/A1764) in the basal core promoter are important mutations that alter expression of the hepatitis B e antigen (HBeAg). The HBeAg is important for establishing viral persistence. The precore G1896A mutation abrogates the expression of HBeAg. Numerous other mutations alter the disease severity and progression. It is predictive that the infected patient has high risk of hepatocellular carcinoma if the genotype C is incriminated or if HBV possesses basal core promoter double mutation. Association of the remaining genotypes have been noted but with less degree than genotype C. Phenotypic assays of the different HBV protein markers with different molecular techniques illustrate the replication efficiency of the virus in cell lines. This review will discuss various mutations into their association with liver disease severity and progression as well as virus replication.