Biological characteristics of rt181T/sW172* HBV are similar among distinct genotypes

Abstract Background: The influence of genotypes on disease progression and clinical outcome of HBV infection is noted. The impact of HBV genotypes on rtA181T/sW172* mutation remains unclear. Patients and Methods: Clinical characteristics of 69 patients with rtA181T/sW172* mutation and 39 patients with rtA181V mutation were analyzed in this study. Fifteen serum specimens with rtA181T/sW172* mutation from different genotypes were collected for cloning and sequence analysis. HBV markers in HepG2 cells encoding different proportions of rtA181T/sW172* mutation and wild type strains were detected in genotype A, B, C and D, respectively.Results: No statistically difference was detected between rtA181T and rtA181V group regarding mean age, sex ratio, liver functions, HBV DNA load and HBeAg positive rate, except for HBsAg level (rtA181T group = 3.07±0.54 lg IU/ml vs rtA181V group = 3.29±0.43 lg IU/ml, P=0.037). Among 69 patients with rtA181T/sW172* mutation, HBV genotypes B and C accounted for 17.0% and 83.0%, respectively. The rate of genotype B was lower in rtA181T group (10.1%) than that in rtA181V group (29.7%), whereas genotype C was higher in rtA181T group (89.9%) than that in rtA181V group (70.3%). HBV rtA181T/sW172* mutant coexisted with wild type strains, accounted for 25% to 90% in all HBV strains. The distribution proportion showed no statistical difference between genotype B and C (59.2%±24.3% vs. 61.2%±19.1% , P=0.86). In transfection experiments, the level of HBV DNA was the highest for genotype B, while HBsAg was expressed in the highest level for genotype A. HBsAg and virus particle were barely detected in the supernatants of rtA181T/sW172* HBV clones in all genotypes. As the proportion of wild type HBV plasmid increased, deficiency of rt181T/sW172* mutation was complemented in all genotypes. No significant difference of the relative expression was found among distinct genotypes (P >0.05).Conclusions: HBV rtA181T/sW172* mutational pattern may be influenced by genotypes, but biological characteristics of this mutation is similar among distinct genotypes.