RESUMO
INTRODUCTION AND AIM: Hepatitis B virus (HBV) infection remains a public health problem worldwide. In addition, HBV infection results are influenced by various virological, immunological, and genetic factors. Inducible T-cell costimulator (ICOS) polymorphisms involving chronic HBV infection have been confirmed in previous studies. This study was to explore the effects of ICOS single nucleotide polymorphisms in HBV subtypes and their interactions with viral mutations on HBV infection outcomes. MATERIAL AND METHODS: A total of 1,636 Han Chinese individuals were recruited, including 47 asymptomatic HBV carriers (ASC), 353 chronic hepatitis B (CHB) patients, 327 HBV-related liver cirrhosis (LC) patients, 193 HBV-related hepatocellular carcinoma (HCC) patients, 464 patients with spontaneous recovery from HBV infection (SR), and 252 healthy controls (HC). DNA samples from these subjects were genotyped for four ICOS SNPs (rs11883722, rs10932029, rs1559931, and rs4675379). Direct sequencing was used to determine the HBV mutations in the enhancer II, basal core promoter, and pre-core regions. RESULTS: We found that the genotype "TC" of ICOS rs10932029 SNP was associated with decreased HBV-related LC risk in the genotype C group. Additionally, the A1762T, G1764A and A1762T/G1764A mutations were associated with an increased risk of LC in the genotype C group. Further study indicated that interactions between ICOS rs10932029 genotype "TC" and A1762T or A1762T/G1764A mutations significantly decreased the LC risk in the genotype C group. CONCLUSION: The rs10932029 genotype "TC" might be an LC-protective factor for HBV genotype C infection. The interactions between the rs10932029 genotype "TC" and A1762T or A1762T/G1764A mutations could decrease the risk of LC.