Okamoto Hiroaki, Nishizawa Tsutomu, Takahashi Masaharu, Tawara Akio, Peng Yihong, Kishimoto Junichi, Wang Yu
Immunology Division and Division of Molecular Virology, Jichi Medical School, Tochigi-Ken 329-0498, Japan1.
First Department of Internal Medicine, Yamanashi Medical University, Yamanashi-Ken 409-3898, Japan2.
J Gen Virol. 2001 Sep;82(Pt 9):2041-2050. doi: 10.1099/0022-1317-82-9-2041.
TT virus (TTV) was recovered from the sera of tupaias (Tupaia belangeri chinensis) by PCR using primers derived from the noncoding region of the human TTV genome, and its entire genomic sequence was determined. One tupaia TTV isolate (Tbc-TTV14) consisted of only 2199 nucleotides (nt) and had three open reading frames (ORFs), spanning 1506 nt (ORF1), 177 nt (ORF2) and 642 nt (ORF3), which were in the same orientation as the ORFs of the human prototype TTV (TA278). ORF3 was presumed to arise from a splicing of TTV mRNA, similar to reported human TTVs whose spliced mRNAs have been identified, and encoded a joint protein of 214 amino acids with a Ser-, Lys- and Arg-rich sequence at the C terminus. Tbc-TTV14 was less than 50% similar to previously reported TTVs of 3.4-3.9 kb and TTV-like mini viruses (TLMVs) of 2.8-3.0 kb isolated from humans and non-human primates, and known animal circoviruses. Although Tbc-TTV14 has a genomic length similar to animal circoviruses (1.8-2.3 kb), Tbc-TTV14 resembled TTVs and TLMVs with regard to putative genomic organization and transcription profile. Conserved motifs were commonly observed in the coding and noncoding regions of the Tbc-TTV14 genome and in all TTV and TLMV genomes. Phylogenetic analysis revealed that Tbc-TTV14 is the closest to TLMVs, and is closer to TTVs isolated from tamarin and douroucouli than to TTVs isolated from humans and chimpanzees. These results indicate that tupaias are naturally infected with a new TTV species that has not been identified among primates.
通过使用源自人TTV基因组非编码区的引物进行PCR，从树鼩（Tupaia belangeri chinensis）血清中分离出TT病毒（TTV），并测定了其完整基因组序列。一种树鼩TTV分离株（Tbc-TTV14）仅由2199个核苷酸（nt）组成，有三个开放阅读框（ORF），分别跨越1506 nt（ORF1）、177 nt（ORF2）和642 nt（ORF3），其方向与人类原型TTV（TA278）的ORF相同。推测ORF3源于TTV mRNA的剪接，类似于已报道的其剪接mRNA已被鉴定的人TTV，编码一种214个氨基酸的联合蛋白，在C末端有富含丝氨酸、赖氨酸和精氨酸的序列。Tbc-TTV14与先前报道的3.4 - 3.9 kb的TTV以及从人和非人灵长类动物中分离出的2.8 - 3.0 kb的TTV样微小病毒（TLMV）和已知动物环状病毒的相似度低于50%。尽管Tbc-TTV14的基因组长度与动物环状病毒（1.8 - 2.3 kb）相似，但在假定的基因组组织和转录谱方面，Tbc-TTV14与TTV和TLMV相似。在Tbc-TTV14基因组的编码和非编码区以及所有TTV和TLMV基因组中普遍观察到保守基序。系统发育分析表明，Tbc-TTV14与TLMV最接近，与从绢毛猴和夜猴分离出的TTV相比，比从人和黑猩猩分离出的TTV更接近。这些结果表明树鼩自然感染了一种在灵长类动物中尚未被鉴定出的新型TTV物种。
