Sequence analysis of the S gene region in HBV DNA from patients positive for both HBsAg and HBsAb tests

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http://onlinelibrary.wiley.com/doi/10.1111/j.1872-034X.2010.00723.x/abstract

Sequence analysis of the S gene region in HBV DNA from patients positive for

both HBsAg and HBsAb tests

Lei Wang, Hua Liu, Xiaoxiao Ning, Feng GaoArticle first published online: 25 OCT

2010

DOI: 10.1111/j.1872-034X.2010.00723.x

© 2010 The Japan Society of Hepatology

Issue

Hepatology Research

Volume 40, Issue 12, pages 1212–1218, December 2010

Aims:  To study the characteristics of mutation in the amino acids coded by

the S gene region in the HBV DNA sequence and to comprehensively explore and

analyze the cause of the double positive result phenomena in both HBsAg and

HBsAb tests.

Methods:  Specimens collected from 43 cases of chronic hepatitis B patients

with positive results for both HBsAg and HBsAb tests were used as the

experimental group; specimens collected from 43 cases randomly picked from all

patients with chronic hepatitis B with a single positive result for HBsAg test

were used as the control group. In HBV DNA, the S gene region was amplified and

sequenced. Amino acid sequences were grouped, and mutations were analyzed based

on the sequencing results.

Results:  The patients were infected with HBV of the genotype B and C and

those who with genotype C show more mutations than genotype B carriers. Compared

with the control group, the experimental group had a marked increase in S gene

amino acid mutations; a higher amino acid mutation rate was observed in the

first loop (aa124–137) of the a-determinant (aa124–147) and there was a

statistical difference (genotype B: 2.68% vs. 0.00%, P = 0.041; genotype C:

7.14% vs. 2.01%, P < 0.001).

Conclusion:  The first loop in a-determinant of S gene sequence possesses a

large numbers of mutated amino acids, leading to changes of antigenicity and

simultaneous positive results in both HBsAg and HBsAb tests finally.