title: [Distribution of TT virus genotypes in blood donors of northern China].
abstract: OBJECTIVE
  To analyse the distribution of TT virus (TTV) genotypes in the blood donors of Northern China.
  
  
  METHODS
  TTV DNA was detected using nested-PCR and its PCR products were cloned into the pGEM-T vector for sequencing. The sequences were analysed using ClustalX and Neighbor joining programs.
  
  
  RESULTS
  Nucleotide identity of the 12 strains of Chinese TTV isolated was 53%-95%. Nucleotide homology between the representatives of genotype 1a and 1b [TX011(O), TA278] and the 12 strains of TTV was 55%-94% and 55%-75%, respectively. Of the 12 Chinese TTV isolates, eight were classified as genotype 1b, three as unknown genotype X and one as unknown genotype Y, which accounted for 66.7%, 25% and 8.3%, respectively.
  
  
  CONCLUSIONS
  An exceptional degree of genetic heterogeneity was displayed in TTV nucleotide sequences and they could be, at least, classified as three genotypes. Genotype 1b may be the main prevalent genotype in blood donors of Northern China.
authors.affiliation: Department of Hepatitis, National Institute for the Control of Pharmaceutical and Biological Products, Beijing 100050, China.
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Zhang
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D001782:Blood Donors; D002681:China; D004266:DNA Virus Infections / Q000097:blood; D018740:Genetic Heterogeneity; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D022783:Torque teno virus / Q000235:genetics*