Distribution of pre-pre-S and pre-X sequences in hepatitis B virus genome of different genotypes
Objective To investigate the distribution of p re -pre-S and pre-X sequences in hepatitis B virus genome of different genotypes . Methods The distribution of pre-pre-S and pre-X sequ ences was analyzed in 38 hepatitis B virus (HBV) complete sequences of different genotypes(35 from GenBank and 3 from our laboratory) using MegAlign program fro m DNAstar software. The Blast software was used to find the sequences of nucleot ide acids and deduced amino acids similar to pre-pre-S and pre-X region in 59 8 HBV strains from GenBank. ResultsSequences of pre-pre -S region were present in all genotypes of HBV except genotype D. Pre-pre-S s equences, identified as an open reading frame (ORF), were only found in HBV geno me of genotype C, E and H. Sequences of pre-X as well as its ORF were only foun d in HBV genome of genotype C. Of 598 HBV strains of different genotypes from Ge nBank, 36 amino acid sequences shared high similarity with pre-pre-S sequence, and 47 amino acid sequences had high similarity with pre-X analyzed by Blast s oftware. Conclusion The pre-pre-S sequences are present in all HBV genotypes except genotype D, while pre-X sequences are found only i n HBV genotype C.