title: Analysis of the entire genomes of thirteen TT virus variants classifiable into the fourth and fifth genetic groups, isolated from viremic infants.
abstract: TT virus (TTV) DNA in serum samples obtained from 24 TTV-infected infants was amplified by polymerase chain reaction (PCR) with inverse primers derived from the untranslated region. The amplified PCR products were molecularly cloned; six clones each were analyzed. Seventy-six (53%) of the 144 TTV clones were classified into group 4 (YONBAN isolates), and 22 (15%) into a novel genetic group (group 5). The TTV clones in group 4 were classified into 9 types, and those in group 5 into 4 types. The entire nucleotide sequence of one representative clone each from the 13 types were determined; they comprised 3570-3770 nucleotides, and had poor homology to TTVs of groups 1-3 (TA278, PMV and SANBAN isolates). A phylogenetic tree based on the entire nucleotide sequence of open reading frame 1 confirmed the presence of five distinct clusters separated by a bootstrap value of 100%. Analysis of 13 TTV variants demonstrated preservation of the genomic organization and transcription profile in all TTV groups. TTV group 4 was detected in 54% or 72% of 7-to-12-month-old infants in Japan and China, respectively, which is comparable with that among adults in the respective country, indicating early and frequent acquisition of this TTV group in infancy.
authors.affiliation: Immunology Division, Jichi Medical School, Tochigi-Ken, Japan.
authors.forename: Y H
authors.initials: YH
authors.lastname: Peng
authors.forename: T
authors.initials: T
authors.lastname: Nishizawa
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: T
authors.initials: T
authors.lastname: Ishikawa
authors.forename: A
authors.initials: A
authors.lastname: Yoshikawa
authors.forename: H
authors.initials: H
authors.lastname: Okamoto
mesh_terms: D000328:Adult; D001483:Base Sequence; D002681:China; D003001:Cloning, Molecular; D004266:DNA Virus Infections / Q000821:virology*; D004279:DNA, Viral / Q000097:blood; D005260:Female; D014644:Genetic Variation; D016679:Genome, Viral; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007564:Japan; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D022783:Torque teno virus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D014766:Viremia / Q000821:virology*
chemical_list: D004279:DNA, Viral