hepatitis b virus surface antigen variants clustered within immune epitopes in chronic hepatitis b carriers from hormozgan province, south of iran

Abstract

Objective(s)The aim of this study was to characterize the hepatitis B virus surface protein genotypes and sequence variations among hepatitis B virus surface antigen (HBsAg) positive chronic patients in Hormozgan province, south of Iran.Materials and MethodsA total of 8 patients enrolled in this study. The surface gene was amplified and directly sequenced. Genotypes and nucleotide/amino acid substitutions were identified compared to the sequences obtained from the database.ResultsAll strains belonged to genotype D. Overall 77 “muta¬tions” occurred at 45 nucleotide positions, of them, 44 (57.14%) were silent (no amino acid altering) and 33 (42.86%) were missense (amino acid changing). A number of 24 (80%) out of 30 amino acid changes occurred in different immune epitopes within surface protein, of which, 9 (30%) in B cell epitopes in 7 residues (2 occurred in “a” determinant region); 8 (42.1%) in T helper epitopes in 7 residues and 7 (10%) in 4 residues inside CTL epitopes.ConclusionHepatitis B virus genome containing mutated immune epitopes no longer could be recognized by specific T-cells of the host immune surveillance and did not enhance anti-HBs production. This could led to the progression of chronicity of hepatitis B virus infection.