Hepatitis B Virus Surface Antigen Variants Clustered Within Immune Epitopes in Chronic Hepatitis B Carriers From Hormozgan Province, South of Iran



Norouzi M¹ ; Ghorashi SA¹ ; Ataei B² ; Yaran M² ; Malekzadeh R³ ; Alavian SM⁴ ; Judaki MA⁵ ; Ghamari S⁵ ; Namazi A⁵ ; Rahimnia R⁵ ; Khedive A⁵ ; Jazayeri SM⁵
Source: Iranian Journal of Basic Medical Sciences Published:2010

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 Methods: A 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. Results: All strains belonged to genotype D. Overall 77 mutations 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. Conclusion: Hepatitis 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.