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Background: Chronic hepatitis B virus (HBV) infection is a multi-factorial disease that is accompanied with serious clinical complications. Host’s genetic background, especially immune–genetic factors, is critical in the pathogenesis of infection. Gamma interferon ((INF-γ) and its receptor have an important role in immune response to the virus and clinical course of the disease. The aim of this study is to investigate the association between single nucleotide polymorphism -611G/A located in promoter of gamma interferon receptor1 gene (INFGR1) and chronic HBV infection. Materials and Methods: In this Case Control study, genomic DNA from peripheral blood samples of 150 chronically HBV infected patients and 150 healthy controls was extracted by phenol-chloroform method. DNA analysis was performed by PCR-RFLP method and P<0.05 was considered significant. Results: After stages of genotyping and statistical analysis, a significant difference was observed between patient and control group, so that genotype GG was higher in the control group compared to the patient group. Conclusion: The host’s immune-genetic background can play an important role in the pathogenesis of infectious disease. Variations in INFGR1 were related to several diseases. The results showed that the presence of GG allele is accompanied by a decrease in susceptibility to chronic HBV infection.

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  Background: In spite of designing and applying an effective vaccine against Hepatitis B virus (HBV), chronic infection with this virus is still one of the most important health problems worldwide. Host genetic background including single nucleotide polymorphisms play a significant role in chronicity or clearance of the infection. The final product of programmed cell death 1 gene (PDCD1) is expressed frequently on T-cells and in chronic viral infections, prevent the virus-specific T-cell response against the virus. In this study, the association of a single nucleotide polymorphism (+7146A/G) in intron 4 of PD1 gene with chronic hepatitis B infection in Iranian population has been assessed.

  Materials and Methods: 212 chronic HBV patients and 208 healthy controls were analyzed in this case-control study. Genomic DNA of the studied individuals was extracted and after performing polymerase chain reaction (PCR), polymorphism of +7146 was determined via RFLP method.

  Results: Frequencies of GG, GA and AA genotypes on position 7146 of the intron 4 of PD1 gene were 77.4%, 20.7% and 1.9% in patient group and 80.8%, 15.4% and 3.8% in control group, respectively. After statistical analysis, No significant difference was observed between patient and control groups (p=0.198).

  Conclusion: Genotype frequencies in the studied population are in accordance with the results of previous studies. Results of the present study suggest that there is not any association between A/G single nucleotide polymorphism in intron 4 of PD1 gene and susceptibility to chronic hepatitis B in Iranian population.