Molecular virological characteristics of occult hepatitis B virus infection in blood donors in Shenzhen from 2010 to 2012

Abstract

Objective To investigate the molecular virological characteristics of occult hepatitis B virus (HBV) infection (OBI) in Shenzhen. Methods A total of 310 167 blood samples were collected from donors between April 2010 and December 2012 in Shenzhen Blood Center. Hepatitis B surface antigen (HBsAg)-/HBV DNA+ samples were screened. HBV DNA was quantified by quantitative polymerase chain reaction (PCR). S region was tested by nested PCR. Molecular virological characteristics of OBI samples were further analyzed. Genotyping was conducted by MEGA software to construct the phylogenetic tree by neighbor-joint. Results Among 121 HBsAg-/HBV DNA+ samples, 99 samples were identified as OBI. Genotyping was conducted in 69 samples, with 57 of genotype B and 12 of genotype C. F134I/L mutation in 12 samples in the major hydrophilic region (MHR) of amino acids was the most frequent mutation in B genotype strains, and there was no obvious amino acid mutation in C genotype strains. In other S fragment sequences, 10 of the B genotype OBI stains had P105R, 10 had Q101R/H/K, 9 had G102I, V177A and 9 had S39N amino acid replacements. While 10 of the C genotype OBI strains had S53L amino acid substitution. Conclusions Mutation, insertion and termination of amino acids in S protein may influence HBV replication and protein expression, which is related with the emergence and development of OBI. Key words: Hepatitis B virus; Occult infection; Blood donors; Genotype; Molecular virological characterization