en عمومى General پژوهشي Original article Background and Aims: chronic HBV infection is one of the most common viral infections in worldwide which many factors such as genetic factors are involved in pathogenesis of disease. Gamma interferon (IFN-γ) and its receptor (INFGR) play a critical role in the immune response to HBV infection. Single nucleotide polymorphisms (SNPs) are effective on level of gene expression, The aim of this study is explore the effect of -56T/C(SNP) located in promoter of gamma interferon receptor1 (INFGR1)gene on chronic HBV infection. Methods: Genomic DNA from peripheral blood samples of 150 chronically HBV infected patients and 150 healthy controls was extracted by phenol-chloroform method and DNA analysis and genotyping was performed by PCR-RFLP method. Results: According to obtained genotyping and also statistical analysis, it was observed that between the patients and control group a significant difference existed and the genotypes of TC and CC were high in control group compared to the patients group. Conclusion: The host genetic factors can plays an important role in pathogenesis of HBV infection, Genetic variations in INFGR1 was related to several diseases, in this study we surveyed association between -56T/C (SNP) in INFGR1 and chronic HBV infection, the results of our study showed that presence of C and TC alleles in our population is related to decrease risk susceptibility to chronic infection. Hepatitis B Virus, RFLP, gamma interferon receptor 19 24 http://journal.isv.org.ir/browse.php?a_code=A-10-1-45&slc_lang=en&sid=1 S Khanizadeh 10031947532846003689 10031947532846003689 No Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran M Ravanshad 10031947532846003690 10031947532846003690 Yes Department of Virology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran SR Mohebbi 10031947532846003691 10031947532846003691 No Research Center for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences. Tehran, Iran H Naghoosi 10031947532846003692 10031947532846003692 No Research Center for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences. Tehran, Iran SD Mousavinasab 10031947532846003693 10031947532846003693 No Department of Virology, School of Medical Sciences, Tarbiat Modares University, Tehran, Iran S Romnani 10031947532846003694 10031947532846003694 No Research Center for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences. Tehran, Iran P Azimzadeh 10031947532846003695 10031947532846003695 No Research Center for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences. Tehran, Iran A Sharifian 10031947532846003696 10031947532846003696 No Research Center for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences. Tehran, Iran MR Zali 10031947532846003697 10031947532846003697 No Research Center for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences. Tehran, Iran