Real-time quantification of hepatitis B virus core-promoter and pre-core mutants during hepatitis E antigen seroconversion

Background/Aims Detection of hepatitis B virus (HBV) core-promoter A1762T-G1764A and pre-core G1896A mutants has relied on qualitative assays. We tested the hypothesis that the quantity of A1762T-G1764A and G1896A mutants might have clinical impact, by quantifying these mutants before and after HBe antigen (HBeAg) seroconversion in 58 patients. Methods A real-time quantitative-polymerase chain reaction (Q-PCR) was developed, using minor groove binder (MGB)-conjugated TaqMan probes to impart reaction specificity for wildtype/mutant HBV populations. Results Significant quantities (>20%) of core-promoter A1762T-G1764A mutant existed in 65% of patients before and after HBeAg seroconversion, and were significantly changed (>20% increase/decrease) in 13% of patients after seroconversion. Quantity of A1762T-G1764A mutants was positively correlated with alanine aminotransferase (ALT) (P<0.001) and HBV DNA (P<0.001) levels, both before and after HBeAg seroconversion. Significant quantities of pre-core G1896A mutant existed in about 90% of patients before and after HBeAg seroconversion, and were changed in 16% of patients after seroconversion. Quantity of G1896A mutant was negatively correlated with ALT (P=0.044) and HBV DNA (P=0.007) levels. Conclusions The A1762T-G1764A and G1896A mutants existed in a high proportion of patients before and were unaffected after HbeAg seroconversion. The quantities of A1762T-G1764A mutant were positively and G1896A mutant negatively correlated with liver inflammation and viral replication.