Coexistence of hepatitis B surface antigen and anti-HBs in Chinese chronic hepatitis B virus patients relating to genotype C and mutations in the S and P gene reverse transcriptase region

摘要

We aimed to determine the prevalence of the coexistence of HBsAg and anti-HBs and to analyze the clinical and virological features of infection, including amino acid (aa) patterns of the S gene and reverse transcriptase (RT) region in Chinese chronic hepatitis B (CHB) patients. Fifty-four (2. 90%) CHB patients who were positive for both HBsAg and anti-HBs were tested, and sequences were obtained from 52 of them as well as 48 patients from a control group. S gene and RT region sequences were amplified and sequenced using in-house protocols. There was no significant difference between patients with and without anti-HBs with regard to age, gender, alanine aminotransferase level, and the proportion positive for HBeAg and HBcAb. The occurrence of genotype C (P = 0. 001) and anti-HBeAb positivity (P = 0. 027) was significantly higher in HBsAg+/anti-HBs+ individuals. In the S gene, the number of mutated residues in the HBsAg+/anti-HBs+ group was markedly higher than in control patients (1. 88 versus 1. 02 substitutions per 100 amino acids, P = 0. 022). The amino acid exchange occurred mostly within the N-terminal region (2. 15 versus 0. 87 substitutions per 100 amino acids, P = 0. 023) and the "a" determinant (3. 61 versus 1. 56 substitutions per 100 amino acids, P = 0. 049) in the two groups. In the RT region, the mean number of substitution per 100 aa showed a tendency to be significantly higher in HBsAg+/anti-HBs+ patients than in controls (2. 34 versus 1. 46, P = 0. 040). This study showed a prevalence of coexistence of anti-HBs in HBsAg-positive patients and an increased frequency of genotype C and aa variability within both HBsAg and RT involving functionally important regions of those proteins.