TY - JOUR
T1 - Identification of a novel 23 kDa protein encoded by putative open reading frame 2 of TT virus (TTV) genotype 1 different from the other genotypes
AU - Tanaka, Y.
AU - Orito, E.
AU - Ohno, T.
AU - Nakano, T.
AU - Hayashi, K.
AU - Kato, T.
AU - Mukaide, M.
AU - Iida, S.
AU - Mizokami, M.
PY - 2000
Y1 - 2000
N2 - 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 150aa (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 G1b 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.
AB - 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 150aa (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 G1b 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.
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U2 - 10.1007/s007050070097
DO - 10.1007/s007050070097
M3 - Article
C2 - 10963344
AN - SCOPUS:0033648589
SN - 0304-8608
VL - 145
SP - 1385
EP - 1398
JO - Archives of Virology
JF - Archives of Virology
IS - 7
ER -