title: Nucleic acid sequence analysis of basal core promoter/precore/core region of hepatitis B virus isolated from chronic carriers of the virus from Kolkata, eastern India: low frequency of mutation in the precore region.
abstract: OBJECTIVE
  The aim of the present study was to characterize the predominant hepatitis B virus (HBV) strains and their molecular variants present in the HBV isolates of the different genotypes found among the chronic carriers of the virus in our community.
  
  
  METHODS
  Precore/core and core promoter regions of HBV DNA were amplified by polymerase chain reaction and then subjected to direct sequencing. Of the 64 hepatitis B surface antigen (HBsAg)-positive chronic HBV carriers investigated, 44 were HBeAg negative and 20 were HBeAg positive.
  
  
  RESULTS
  In addition to genotype D, which was the predominant genotype, 12 genotype C (18.7%) and 6 genotype A (9.4%) were also detected. Presence of T at nt 1858 has often been related to the development of precore stop mutation at nt 1896, while that of C has been related to the development of 1762-1764 double mutation. In our study group, 39 of the 44 HBeAg-negative samples have T1858. The precore stop codon mutation was found in only 8 (18%) of the HBeAg-negative samples. More than half of the HBeAg-negative samples had wild-type sequence in the precore region. The core promoter region could be sequenced from 40 samples, and 1762-1764 double mutation was detected in 13 (32.5%) of them. No significant changes could be detected in the core amino acid sequence of these isolates.
  
  
  CONCLUSIONS
  The pattern of core promoter and precore mutation of HBV isolates in the present study is atypical and not in accordance with reports from other parts of the world, where genotype D and genotype C with T at codon 1858 are common.
authors: ICMR Virus Unit, Institute of Post Graduate Medical Education and Research, Kolkata, India.
authors: Arup
authors: A
authors: Banerjee
authors: Soma
authors: S
authors: Banerjee
authors: Abhijit
authors: A
authors: Chowdhury
authors: Amal
authors: A
authors: Santra
authors: Sujit
authors: S
authors: Chowdhury
authors: Susanta
authors: S
authors: Roychowdhury
authors: Chinmoy Kumar
authors: CK
authors: Panda
authors: Sujit Kumar
authors: SK
authors: Bhattacharya
authors: Runu
authors: R
authors: Chakravarty
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001483:Base Sequence; D002353:Carrier State / Q000821:virology*; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000737:chemistry / Q000302:isolation & purification; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000821:virology*; D006513:Hepatitis B e Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D017421:Sequence Analysis; D017422:Sequence Analysis, DNA; D014758:Viral Core Proteins / Q000235:genetics*
chemical_list: D004279:DNA, Viral; D006513:Hepatitis B e Antigens; D014758:Viral Core Proteins