title: Co-infection with hepatitis B virus genotype D and other genotypes in Western Japan.
abstract: OBJECTIVE
  Genotypes B and C are the prevalent hepatitis B virus (HBV) genotypes in eastern Asia. Although very rare in this region of the world, genotype D was found to be prevalent in a small area of western Japan. In this study, we confirm the frequency and clinical significance of co-infection with different genotypes among patients from that area infected with genotype D.
  
  
  METHODS
  Twenty-three patients from the same area of western Japan infected with HBV genotype D, determined using a genotyping enzyme immunoassay, were studied. Cloning was done using DNA extracted from serum samples, and polymerase chain reaction assays with the restriction fragment length polymorphism for HBV genotyping were performed with 10 clones from each patient.
  
  
  RESULTS
  Four (17.4%) of the 23 patients were found to be co-infected with HBV genotype C, and the HB surface antigen subtype was ayw in both mono- and co-infected patients. No clinical differences were found between mono-infected and co-infected patients carrying genotype D.
  
  
  CONCLUSIONS
  A significant number of patients from the study area found to be infected with HBV genotype D were co-infected with genotype C. Additional study with a larger number of patients is needed to elucidate the possible clinical significance.
authors.affiliation: Third Department of Internal Medicine, Ehime University School of Medicine, Shigenobu-cho, Onsen-gun, Ehime 791-0295, Japan.
authors.forename: Kojiro
authors.initials: K
authors.lastname: Michitaka
authors.forename: Norio
authors.initials: N
authors.lastname: Horiike
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Tran Nhu
authors.initials: TN
authors.lastname: Duong
authors.forename: Kana
authors.initials: K
authors.lastname: Matsuura
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Tokumoto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Hiasa
authors.forename: Fazle S M
authors.initials: FS
authors.lastname: Akbar
authors.forename: Morikazu
authors.initials: M
authors.lastname: Onji
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D003001:Cloning, Molecular; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000453:epidemiology / Q000821:virology*; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics*; D006801:Humans; D007124:Immunoenzyme Techniques; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length