S gene region of HBV-DNA is responsible for expression of surface antigens
and includes a-determinant region. Thus, mutation(s) in this region would afford
HBV variants a distinct survival advantage. The aim of this study was to search
the mutations of the S gene region in different patient groups infected with
Genotype D variants and was to analyse biological significance of these mutations.
Beside this, we investigated S gene mutation inductance among family members.
Forty HBV-DNA positive patients were determined among 132 HBsAg carriers by
first stage of Semi-Nested PCR. Genotypes and subtypes were established by sequencing
of the amplified S gene regions. Variants were compared with original sequences
of these serotypes and mutations were fixed. All variants were designated as
Genotype D and subtype ayw3. Ten kinds of point mutations were identified within
the S region. The rates of mutations were determined in chronic patients and
family members as being maximum among the other groups. The amino acid mutations
of 125 (M→T) and 127 (T→P) were found on the first loop of a-determinant.
The other consequence was mutation inductance in a family member. We found some
mutations on S gene region known to be stable and observed that some of these
mutations were effective on S gene expressions. Identified mutations on a-determinant
may provide advantage to mutant about escaping from immune system.
Mehmet Ozaslan , Canan Can and Arzu Barsgan , 2006. Mutations on S Gene Region of Hepatitis B Virus Genotype D and Biological Significant Analyses of These Mutations. Journal of Medical Sciences, 6: 79-86.