Complete genome sequence and phylogenetic relatedness of hepatitis B virus isolates from Iran

Abstract number: 1134_03_300

Amini-Bavil-Olyaee S., Sarrami-Forooshani R., Azizi M., Adeli A., Sabahi F., Abachi M., Mahboudi F.

Objectives:  

To date, no study has been carried out by the hepatitis B virus (HBV) complete genome sequence from Iranian HBV infected patients. The objective of this study was to investigate phylogenetic analysis, genome organization and genotype characterization of HBV strains which obtained from Iranian chronic infected subjects and compared with HBV genotypes reported from the Middle East countries.

Methods:  

HBsAg-positive sera were collected from the five Iranian chronic HBV carriers. The complete HBV genome was amplified using two novel primers that have introduced Hind III and EcoR I restriction enzyme cleavage sites. The HBV full-length amplicon was cloned into pCR^®2.1 plasmid and then sequenced. The Iranian HBV genome sequences were compared with 23 human HBV genome sequences. Alignment was achieved using CLUSTALX software, genetic distance was estimated using the Kimura two-parameter algorithm and then phylogenetic trees were constructed by the neighbor-joining method. Recombination was investigated using SimPlot, BootScanning programme and a web-based genotyping tool for viral sequences.

Results:  

Results showed that the five strains were closely related to each other, with 97–100% nucleotide similarity. Phylogenetic analysis based on the complete genome sequence revealed that all stains were classified into genotype D. The S gene encoded Arg122, Pro127 and Lys160 corresponding to subtype ayw2. All strains had nucleotide lengths of 3182 bp except the IR-P4 strain with a unique 3185 bp and with a Phe89 insertion in the X gene. The intragenotypic divergence of the complete genome sequence of Iranian strains was 1.8% and the intergenotypic to the genotype D was 3.8% and to other genotypes was 7.9–15.4%. The Middle East countries HBV gene sequences analyses findings showed that HBV genotype D subtype ayw2 is the most dominant. Results showed that Saudi Arabia isolates has the most similarity to Iranian isolates and then Turkish, Egyptian and Yemeni isolates ranked next, respectively.

Conclusion:  

This is the first report of the full-length nucleotide sequences and genome organization investigation of the HBV isolates from Iran. This study revealed that the HBV genotype D, subtype ayw2 is present in the Iranian infected patients. A unique amino acid insertion in the X gene of the one Iranian strain was detected with an unprecedented length of 3185 bp. The update Middle East HBV geographical genotypic distribution map was depicted.