Hepatitis B precore genetic heterogeneity in patients with HBeAg-positive chronic hepatitis B

Abstract

In patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB), HBeAg seroconversion is an important clinical landmark during the natural course of CHB because it usually correlated with the sustained remission and a low risk for disease progression. Mutant viruses carrying the precore G1896A are mainly association with HBeAg seroconversion. The current study evaluated the effects of the genetic heterogeneity in the precore region on HBeAg-positive chronic hepatitis B by in vitro and clinical cross-sectional and longitudinal study. Using direct sequencing and restriction fragment mass polymorphism (RFMP) assay, the genetic heterogeneity in the precore region was analyzed in patients with HBeAg-positive CHB cross-sectionally. The effects of wild-type (WT) and PC G1896A mutation on extracellular excretion of HBV DNA and HBeAg were investigated by site-directed mutagenesis and transfection assays. Additionally, clinical long-term results were evaluated in HBeAg-positive patients with harboring PC G1896A mutant assessing direct sequencing.In patients with HBeAg-positive CHB, 61/248 (24.6%) had detectable PC G1896A mutants according to direct sequencing. Twenty-four patients had only G1896A mutant detectable and 37 had mixed viral strains. However, in all samples with only G1896A mutant by direct sequencing, RFMP assay showed wild-type virus co-existing with PC G1896A mutant. The HBeAg secretion capacity remained identical upon introduction of wild type virus, even though very small amount, during in vitro assay. These results are in agreement with RFMP analysis. In patients harboring G1896A mutant, virologic and serologic responses to antiviral therapy were more favorable compared with those with wild type G1896 (harboring G1896A vs WT: 50.0% vs 30.4%), especially patients with PC G1896A mutant alone. In patients with harboring PC G1896A mutant, positive predictive values of the only detection of PC G1896A mutant by direct sequencing at baseline for HBeAg seroclearance and CR at the end of treatment were 75% and 62.5%, respectively. However, HBeAg-positve patients harboring G1896A mutants often experienced HBV reactivation after stopping therapy. The current study suggested that there were differences in virologic characteristics and clinical prognosis according to the genetic heterogeneity in the precore region in HBeAg-positive CHB. The understanding of PC genetic diversity in HBeAg-positive patients can provide valuable information about the clinical outcomes.