棉铃虫核型多角体病毒几丁质酶基因及杆状病毒 几丁质酶基因的分子进化

用PCR方法扩增了棉铃虫Helicoverpa armigera单粒包埋型核型多角体病毒（HaSNPV）几丁质酶基因，测定了基因编码区的核苷酸全序列。基因编码区全长1.713 bp，可编码570个氨基酸残基组成的多肽，预计分子量为63.6 kD。将所推导的HaSNPV几丁质酶氨基酸序列与其它已知杆状病毒几丁质酶氨基酸序列进行联配比较，结果表明HaSNPV 与谷实夜蛾H.zea单粒包埋型核型多角体病毒（HzSNPV）的氨基酸序列非常相似，同源性高达90.7%，与苜蓿丫纹夜蛾Autographa californica多粒包埋型核型多角体病毒（AcMNPV）、家蚕Bombyx mori核型多角体病毒（BmNPV）、美国白蛾Hyphantria cunea核型多角体病毒（HcNPV）、舞毒蛾Lymantria dispar多粒包埋型核型多角体病毒（LdMNPV）、黄杉毒蛾Orgyia pseudotsugata多粒包埋型核型多角体病毒（OpMNPV）和云杉卷叶蛾Choristoneura fumiferana核型多角体病毒（CfMNPV）氨基酸序列同源性分别为64.4%、64.9%、64.2%、62.9%、66.2%和61.5%。根据氨基酸序列用PC＼GENE程序绘制已知杆状病毒几丁质酶的分子系统树，并与杆状病毒中最为保守的多角体蛋白基因系统树作了比较，结果表明几丁质酶基因和多角体蛋白基因的进化速率是不尽相同的。

Chitinase gene of Helicoverpa armigera nucleopolyhedrovirus and the phylogenetic tree of the baculovirus chitinase genes

The chitinase gene of Helicoverpa armigera single enveloped nucleocapsid nucleopolyhedrovirus (HaSNPV) was amplified by using PCR method. The nucleotide sequence of the coding region was determined. The total length of the coding region was 1.713 bp and was potential to encode a 570 amino acid polypeptide with predicted molecular weight of 636 kD. The alignment of HaSNPV chitinase amino acid sequence with those of other 7 reported baculovirus chitinases showed that HaSNPV chitinase was most closely related to HzSNPV chitinase, with 90.7% amino acid identity. It also shared a high degree of homology with chitinases of AcMNPV, BmNPV, HcNPV, LdMNPV, OpMNPV and CfMNPV, with 64.4%, 64.9%、64.2%、62.9%、66.2% and 61.5% amino acid identity, respectively. A phylogenetic tree of 8 baculovirus chitinases was drawn by using PC＼GENE program, and compared with the phylogenetic tree based on the polyhedrin amino acid sequences of the same 8 baculoviruses. The result showed that the evolutionary rate of chitinase genes was in some degree different to that of polyhedrin genes.