The Influence of B and T Lymphocyte Attenuator Genetic Variants on Susceptibility to Chronic Hepatitis B Virus Infection

Abstract

Background/Aims: B and T lymphocyte attenuator (BTLA) is an immune inhibitory receptor involved in the pathogenesis of chronic viral infections. Little is known about the effects of BTLA gene polymorphisms on chronic hepatitis B virus (HBV) infections. In this study, we investigated whether the polymorphisms of BTLA are associated with the progression of chronic HBV infection. Methods: A total of 382 chronic HBV carriers and 170 healthy individuals in the same region were recruited for this study. The chronic HBV carriers were divided into three groups: asymptomatic HBV carriers (ASC), moderate chronic hepatitis B group (MCHB), and severe chronic hepatitis B group (SCHB). Two BTLA functional single nucleotide polymorphisms (SNPs; rs76844316 and rs9288952) were genotyped by polymerase chain reaction and sequenced directly. Results: The results showed that the frequency of the G allele of rs76844316 was significantly lower in the SCHB group than in the other three groups. Subjects bearing at least one G allele (TG or GG genotype) at rs76844316 had decreased susceptibility to severe chronic hepatitis B compared with those bearing the TT genotype. Haplotype analysis of the two SNPs revealed that the frequency of the G-G haplotype was significantly lower in SCHB patients than in controls. Moreover, in the SCHB group, patients carrying the G allele of rs76844316 tended to have lower ALT levels than those without it. Conclusion: Our findings suggest that the genetic variants of rs76844316 in BTLA influence the susceptibility to severe chronic hepatitis B and might play a protective role against the progression of chronic hepatitis B.