Characterisation of an HBsAg mutant of hepatitis B virus (HBV) isolated from a dialysed patient involved in an occupational accident

BACKGROUND: Mutants of the hepatitis B virus (HBV) following vaccination (escape mutants) have been isolated over the course of the last decade. They consist most commonly of an aminoacid change from glycine to arginine at position 145 of the highly antigenic a determinant of the surface antigen (HBsAg). OBJECTIVE: Description of an escape mutant of HBV identified in the course of the post-exposure follow-up of a percutaneous exposure. METHODS: The viral DNA was extracted from serum samples of a dialysed patient vaccinated against hepatitis B, who developed an acute infection. A direct sequencing was performed on the amplified DNA followed by a sequence analysis. RESULTS AND CONCLUSIONS: A threonine to lysine substitution at position 118 of HBsAg (Thrll8Lys) was observed in the analysed viral aminoacid sequence. Such mutation could have significantly changed the antigenic profile of the HBsAg compared to that of the wild type.