Incidence of Hepatitis B virus Surface Antigen (HBsAg) Mutations in Naïve Treated of Chronic Carriers from Tehran Metropolis, Iran

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Background and Aims: Naturally occuring hepatitis B virus (HBV) with surface mutations in a variety of chronic hepatitis B (CHB) patients who have received no vaccine or HBIG bearing substitutions in surface protein, have been reported. Current knowledge concerning the prevalence of these naturally occurring surface antigen mutations among Iranian carriers is limited. Materials and Methods: In a retrospective cross-sectional study, 119 HBV inactive chronic carriers were enrolled. The surface gene was amplified, sequenced and subsequently aligned using international and national sequence database. Results: All strains belonged to genotype D, subgenotype D1 and subtype ayw2. In 74 (62.18%) of patients, 146 (68.8%) out of 212 amino acid mutations occurred in different immune epitopes within surface protein, of which 28 (19.17%) in B cell, 37 (25.34%) in T helper and 81 (55.47%) inside CTL epitopes. 13 (8.9%) and 15 (10.27%) of amino acid substitutions occurred outside and within the "a" determinant in Major Hydrophilic Region (MHR). While 11 (9.24%) and 77 (64.7%) patients who harbored amino acid mutations, were HBeAg and anti-HBe positive, respectively (p=0.004). 9 and 63 amino acid mutations occurred in different HBsAg epitopes in HBeAg and anti-HBe positive patients, respectively (P=0.04). Conclusion: HBV mutants within the immune epitopes of surface Ag seem to be extremely common among chronic carriers from Tehran, especially those who are anti-HBe positive, indicating that after HBeAg seroconversion, due to the selection pressure of Ag e antibody, the occurrence of mutation is an inevitable effect of the evolutionary process.