Wang W, Leat N, Fielding B, Davison S
Department of Microbiology, University of the Western Cape, Bellville, South Africa.
Virus Genes. 2001;23(1):53-62. doi: 10.1023/a:1011183313021.
Substantial research has been conducted on the immediate early I (ie-1) genes from the prototype baculovirus Auographa californica multicapsid nuclear polyhedrosis virus (AcMNPV) and the Orgyia pseudotsugata multicapsid nuclear polyhedrosis virus (OpMNPV). In both cases ie-1 gene products have been implicated in transcriptional activation and repression. In this study an ie-1 homolog was identified from Trichoplusia ni single nucleocapsid polyhedrosis virus (TniSNPV). Nucleotide sequence analysis indicated that the TniSNPV ie-1 gene consists of a 2,217 nucleotide open reading frame (ORF), encoding a protein with a molecular mass of 84.464 kDa. This represents the largest baculovirus ie-1 gene characterised to date. Of the seven ie-1 homologs identified to date, the TniSNPV ie-1 shared most sequence similarity with the ie-1 gene of Spodoptera exigua MNPV (SeMNPV) (41%). At the nucleotide level, expected TATA and CAGT motifs were found to precede each ie-1 ORE. At the protein level, it was confirmed that the N-termini are poorly conserved, but share the characteristic of having a high proportion of acidic amino acids. In addition it was found that N-terminal regions significantly matched the SET domain in the Swiss-Prot prosite database. The C-terminal regions of the deduced IE-1 sequences were found to be substantially more conserved than the N-termini. Several conserved motifs were identified in the C-terminal sequences. A phylogenetic tree of nine baculovirus IE-1 proteins was constructed using maximum parsimony analysis. The phylogenetic estimation of the ie-1 genes shows that TniSNPV is a member of the previously described lepidopteran NPV group II and it is most closely related to SeMNPV.
针对杆状病毒原型苜蓿银纹夜蛾多粒包埋核型多角体病毒（AcMNPV）和云杉芽卷叶蛾多粒包埋核型多角体病毒（OpMNPV）的立即早期I（ie-1）基因，已经开展了大量研究。在这两种情况下，ie-1基因产物都与转录激活和抑制有关。在本研究中，从粉纹夜蛾单核衣壳多角体病毒（TniSNPV）中鉴定出一个ie-1同源物。核苷酸序列分析表明，TniSNPV的ie-1基因由一个2217个核苷酸的开放阅读框（ORF）组成，编码一个分子量为84.464 kDa的蛋白质。这是迄今为止已鉴定的最大的杆状病毒ie-1基因。在迄今鉴定出的7个ie-1同源物中，TniSNPV的ie-1与甜菜夜蛾多角体病毒（SeMNPV）的ie-1基因具有最高的序列相似性（41%）。在核苷酸水平上，发现每个ie-1 ORF之前都有预期的TATA和CAGT基序。在蛋白质水平上，证实N端保守性较差，但具有高比例酸性氨基酸的特征。此外，发现N端区域与瑞士蛋白质专业数据库中的SET结构域显著匹配。推导的IE-1序列的C端区域比N端保守得多。在C端序列中鉴定出几个保守基序。使用最大简约法构建了9种杆状病毒IE-1蛋白的系统发育树。ie-1基因的系统发育估计表明，TniSNPV是先前描述的鳞翅目NPV II组的成员，并且与SeMNPV关系最为密切。
