Hepatitis B virus preS/S gene mutations and their clinical implications
Hepatitis B virus (HBV) infection remains a major health problem worldwide. HBV is one of the smallest enveloped DNA viruses, and also one of the principal pathogens causing acute and chronic hepatitis. Hepatitis B surface antigen (HBsAg) is a hallmark for the diagnosis of HBV infection, and the quantification of serum HBsAg is regarded as a reliable marker of disease progression and predictor of the outcome. However, the mutations in the preS/S genomic region can occur in HBV DNA sequences from the patients with chronic HBV infection, including genetic recombination, base pair deletion, and point mutations. These variants carrying the modified surface antigen may induce immune escape or occult HBV infection (OBI). Furthermore, the preS/S variants may be the cause of fulminant hepatitis (FH) and fibrosing cholestatic hepatitis (FCH). The mutations in the preS/S region would increase the difficulty of preventing and treatment of HBV infection. In this review, we summarized the prevalence of the mutations in the preS/S region and their effect for the diagnosis or progression of HBV infection.