Identification of a new human DNA virus (TTV-like mini virus, TLMV) intermediately related to TT virus and chicken anemia virus

• Published in: Archives of virology Vol. 145; no. 5; pp. 979 - 993
• Main Authors: Takahashi, K, Iwasa, Y, Hijikata, M, Mishiro, S
• Format: Journal Article
• Language: English
• Published: Wien Springer-Verlag 01-01-2000; New York, NY Springer; Springer Nature B.V
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Chicken anemia virus; Chicken anemia virus - classification; Chicken anemia virus - genetics; Chickens; Circoviridae; Circoviridae - classification; Circoviridae - genetics; Circoviridae - isolation & purification; Circoviridae Infections - transmission; Circoviridae Infections - virology; circular DNA; DNA Primers - genetics; DNA, Viral - blood; DNA, Viral - genetics; Fundamental and applied biological sciences. Psychology; genome; Genome, Viral; Humans; Microbiology; Molecular Sequence Data; new family; nucleotide sequences; Open Reading Frames; Paracircoviridae; Particle Size; proteins; sequence homology; Sequence Homology, Amino Acid; Systematics; Transfusion Reaction; TT virus; vertebrate viruses; Viral Proteins - genetics; Viremia - virology; Virology; viruses; Virus; Characterization; Human; Chicken anemia virus; Genome organization; Taxonomy; Circovirus; New species; Circoviridae; DNA virus
• ISSN: 0304-8608; 1432-8798
• DOI: 10.1007/s007050050689

TT virus (TTV) is the only known human virus with single-stranded circular DNA, with a possible but yet unclear relationship to chicken anemia virus (CAV) of the family Circoviridae. Here we report a new human virus resembling TTV and CAV, designated TTV-like mini virus (TLMV). This non-enveloped virus was smaller (>30 nm) but had a similar density (1. 31–1.34 g/ml in CsCl) to TTV, when a TLMV/TTV-coinfected plasma was analyzed. Full-length sequencing revealed that the TLMV genome was a circular DNA comprising 2860 nt (isolate CBD231); significantly shorter than TTV (TA278, 3852 nt) but longer than CAV (CAECUX1, 2319 nt). A strand-specific hybridization assay using oligonucleotide-coated beads suggested TLMV was negative-stranded, like TTV and CAV. In genomic organization, TLMV was similar to both TTV and CAV. The untranslated region of TLMV resembled CAV in that both had direct repeats, whereas the sequence homology was more evident between TLMV and TTV. The predicted ORF1 protein of TLMV was rich in R/W/F residues at its amino terminus; the richness in W was shared by TTV, F by CAV, and R by both. ORF2 proteins of the three viruses had a common motif, WX₇HX₃CXCX₅H. Thus, TLMV is an intermediate between the remotely related TTV and CAV. Since CAV differs much from other circoviruses, it may better be classified together with TTV and TLMV under a new family: we would coin the Paracircoviridae.