鉴定出一种由1型TT病毒（TTV）推定开放阅读框2编码的新型23kDa蛋白，该蛋白不同于其他基因型。

Identification of a novel 23kDa protein encoded by putative open reading frame 2 of TT virus (TTV) genotype 1 different from the other genotypes.

作者信息

Tanaka Y, Orito E, Ohno T, Nakano T, Hayashi K, Kato T, Mukaide M, Iida S, Mizokami M

机构信息

Second Department of Medicine, Nagoya City University Medical School, Japan.

出版信息

Arch Virol. 2000;145(7):1385-98. doi: 10.1007/s007050070097.

DOI:10.1007/s007050070097

PMID:10963344

Abstract

We report the entire open reading frames (ORFs) sequences of four TT virus (TTV) isolates, one genotype 2 (G2) and three G4 isolates. Despite a DNA virus, TTV possesses high rate of amino acid (aa) substitution: the aa sequence homology of ORF1 and 2 is lower than the nucleotide homology. The partial 'N22' region of ORF1 is suitable for genotyping of 'prototype TTV' isolates, because the phylogenetic tree from partial 'N22' sequence is consistent with that from the entire ORF1. Based on our sequence data, ORF2 from most isolates excluding G1 encode truncated 49 aa (pORF2a) because of an in-frame stop codon, although ORF2s from most G1 isolates encode 202 aa (pORF2ab). Just downstream the stop codon, another ORF encoding a protein of approximately 150 aa (pORF2b) is found, whose homology is quite low among these genotypes. Our in vitro transcription/translation study supports that all G1a and a part of G b without an in-frame stop codon dominantly encode pORF2ab, a novel 23 kDa protein, whereas the other genotypes with an in-frame stop codon encode pORF2b (17 kDa). Our data indicate TTV G1a and a part of G1b should have different characteristics from the other genotypes.

摘要

我们报告了四株TT病毒（TTV）分离株的完整开放阅读框（ORF）序列，其中一株为2型（G2），三株为G4分离株。尽管TTV是一种DNA病毒，但其氨基酸（aa）替换率很高：ORF1和ORF2的氨基酸序列同源性低于核苷酸同源性。ORF1的部分“N22”区域适用于“原型TTV”分离株的基因分型，因为来自部分“N22”序列的系统发育树与来自整个ORF1的系统发育树一致。根据我们的序列数据，除G1外的大多数分离株的ORF2由于框内终止密码子而编码截短的49个氨基酸（pORF2a），而大多数G1分离株的ORF2编码202个氨基酸（pORF2ab）。在终止密码子的下游，发现了另一个编码约150个氨基酸的蛋白质（pORF2b）的ORF，其在这些基因型中的同源性相当低。我们的体外转录/翻译研究支持，所有无框内终止密码子的G1a和部分G1b主要编码pORF2ab，一种新的23 kDa蛋白质，而其他有框内终止密码子的基因型编码pORF2b（17 kDa）。我们的数据表明，TTV G1a和部分G1b应具有与其他基因型不同的特征。