S Gene Mutants Occurrence Among Hepatitis B Carriers in Malaysia

Background: the s gene region of the hepatitis b virus (hbv) codes for surface antigen (hbs ag) and is responsible for classification of hbv strains. objectives: the current study aimed to identify important mutations in the s gene in hepatitis b virus (hbv) isolated from malaysian hbv carriers.materials and methods: isolated hbv dnas were subjected for pcr amplification and sequencing of hbv full genome. results: a total of 76 hbv full genome and 17 partial genome sequences were obtained from the 93 sequenced sera samples genotyping of the full genome sequences by hepseq software revealed a distribution of 49.46%, 48.39% and 2.15% of genotypes c, b, and d, respectively; whereas phylogenetic and jumping profile hidden markov model (jphmm) analysis identified six (7.89%) recombinant b/c strains. the distribution of sub-genotypes were b2 (78.79%) and b3 (21.21%) for genotype b, sub genotype d2 (100%) for genotype d and sub genotype c1 (75.76%), c2 (15.15%), c3 (6.06%) and c5 (3.13%) for genotype c. mutation analysis in the s gene demonstrated two significant mutations which were w182 stop codon and deletion at open reading frame (orf) of pre-s1 with the frequency occurrence of 2.2% (2/93) and 5.4% (5/93), respectively. the two patients with w182 stop codon were both male, infected with hbv genotype c and one showed progression of liver disease to hepatocellular carcinoma (hcc). conclusions: association with sex, genotype and clinical symptoms revealed that the pre-s1 orf deletion occurred in 40% , 40%,and 20% of genotypes b,c, and d respectively, and 80% of the female population, of which all but one were diagnosed with chronic hepatitis b. additionally, several mutations were found in the bcp region with the following incidence rate; c1653 t (8.6%), a1752 g (10.8%),1762 agg--tga 1764 (26.9%), c1766t(2.2%),t1768 a (10.8%), c1858 t (64.5%), g1896 a (25.8%).