RESUMEN
Occult hepatitis B infection [OBI] is identified as a form of hepatitis in which despite the absence of detectable HBsAg, HBV-DNA is observed in peripheral blood of patients. The main aim of this study has been to investigate the association between polymorphisms in +874 of IFN-gamma and +1188 of IL-12 with their serum level in patients suffering from OBI. In this experimental study, plasma samples of 3700 blood donors were tested for the presence of hepatitis B surface antigen [HBsAg] and anti-HBc by ELISA. The HBsAg[-]/anti-HBc[+] samples were selected and screened for HBV-DNA by PCR. HBV-DNA positive samples were assigned as OBI cases and ARMS-PCR techniques were performed to examine the two known polymorphisms within IL-12 and IFN-gamma. In addition, the serum levels of IL-12 and IFN-gamma were also determined by ELISA. Results of this study demonstrated that, 352 [9.5%] out of 3700 blood samples were HBsAg[-]/anti-HBc[+]and HBV-DNA was detected in 57/352 [16.1%] of HBsAg[-]/anti-HBc[+] samples. Our results showed that groups showed significant difference in CC allele of +1188 region of IL-12 and no difference was observed in the other evaluated genes. Our results also showed that the alleles of +1188 region of IL-12 and alleles of +874 of IFN-gamma were also not associated with serum level of cytokines. According to the results of this study, it may be concluded that the polymorphisms in +1188 region of IL-12 and +874 region of IFN-gamma would not affect the expression of both cytokines at serum level in OBI patients