title: Unique hepatitis B virus subgenotype in a primitive tribal community in eastern India.
abstract: Hepatitis B virus (HBV) strains isolated from members of the primitive Paharia ethnic community of Eastern India were studied to gain insight into the genetic diversity and evolution of the virus. The Paharia tribe has remained quite separate from the rest of the Indians and differs culturally, genetically, and linguistically from the mainstream East Indian population, whose HBV strains were previously characterized. Full-length HBV DNA was PCR amplified, cloned, and sequenced. Phylogenetic relationships between the tribal sequences and reference sequences from the mainstream population were assessed, and divergence times of subgenotypes of HBV genotype D were estimated. HBV was found in 2% of the Paharias participating in the study. A predominance of hepatitis B e antigen-negative infection (73%) was observed among the Paharias, and the genome sequences of the HBV strains exhibited relative homogeneity, with a very low prevalence of mutations. The novel feature of Paharia HBV was the exclusive presence of the D5 subgenotype, which was recently identified in Eastern India. Analysis of the four open reading frames (ORFs) of these tribal HBV D5 sequences and comparison with previously reported D1 to D7 sequences enabled the identification of 27 specific amino acid residues, including 6 unique ones, that could be considered D5 signatures. The estimated divergence times among subgenotypes D1 to D5 suggest that D5 was the first to diverge and hence is the most ancient of the D subgenotypes. The presence of a specific, ancient subgenotype of HBV within an ethnically primitive, endogamous population highlights the importance of studies of HBV genetics in well-separated human populations to understand viral transmission between communities and genome evolution.
authors.affiliation: Centre for Liver Research, School of Digestive and Liver Diseases, Institute of Post Graduate Medical Education and Research, Kolkata, India.
authors.forename: Sumantra
authors.initials: S
authors.lastname: Ghosh
authors.forename: Priyanka
authors.initials: P
authors.lastname: Banerjee
authors.forename: Arindam
authors.initials: A
authors.lastname: RoyChoudhury
authors.forename: Sumanta
authors.initials: S
authors.lastname: Sarkar
authors.forename: Alip
authors.initials: A
authors.lastname: Ghosh
authors.forename: Amal
authors.initials: A
authors.lastname: Santra
authors.forename: Soma
authors.initials: S
authors.lastname: Banerjee
authors.forename: Kausik
authors.initials: K
authors.lastname: Das
authors.forename: Bhagirathi
authors.initials: B
authors.lastname: Dwibedi
authors.forename: Shantanu K
authors.initials: SK
authors.lastname: Kar
authors.forename: Vikas Gangadhar
authors.initials: VG
authors.lastname: Rao
authors.forename: Jyothi T
authors.initials: JT
authors.lastname: Bhat
authors.forename: Neeru
authors.initials: N
authors.lastname: Singh
authors.forename: Abhijit
authors.initials: A
authors.lastname: Chowdhury
authors.forename: Simanti
authors.initials: S
authors.lastname: Datta
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003001:Cloning, Molecular; D016000:Cluster Analysis; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006509:Hepatitis B / Q000821:virology*; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D044382:Population Groups; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D004279:DNA, Viral