T Helper and B Cell Escape Mutations within the HBc Gene in Patients with Asymptomatic HBV Infection: A Study From the South-Eastern Region of Iran

Abstract

Background: Escape mutations potentially allow viruses to avoid detection and clearance by the host immune sys-tem and may represent a mechanism through which infections may persist in some patients. The association of the mutations in the HBcAg gene with Hepatitis B asymptomatic carriers (ASC) has not been studied adequately. The current study was aimed to investigate HBcAg18-27 CTL epitope mutations in ASC patients in the South-Eastern region of Iran. Methods: 100 ASC patients were selected for this study and screened for HLA-A2 using flow cytometry. HBV-DNA was extracted from the HLA-A2 positive patients and the HBc gene was amplified using PCR. Direct double sequencing was performed to analyse mutations in the HBc gene of HBV isolates from patients with ASC. Results: Overall, 25 (25%) of individuals were HLA-A2 positive. Direct double sequencing indicated no mutations in the HBcAg18-27 epitope. However, four mutations within the T helper and three mutations within the B cell epitopes of ASC patients were identified. Conclusions: The lack of mutations within the HBcAg18-27 epitope suggests that the antigenicity of this region is not altered in HBV isolates of our patients and therefore antigen presentation would occur normally to the pa-tient’s immune system through HLA-A2. However, in the course of this study we revealed some novel mutations within the T helper and B cell epitopes that may affect the efficiencies of immune response of ASC patients against these novel HBV epitopes. (Clin. Lab. 2012;58:53-60)