家蚕核型多角体病毒株系的分子鉴定初探

A Preliminary Study on Molecular Identification of Bombyx mori Nucleopolyhedrovirus Strains

来自不同地域或蚕区的家蚕核型多角体病毒(Bm NPV)对家蚕的致病力存在较大差异,出现明显的株系分化现象。对Bm NPV流行株系鉴定是病害监测与防控的重要基础。以最早完成基因组测序的Bm NPV-T3株的多角体蛋白基因(polh)序列与其他6个Bm NPV株系进行同源基因序列及氨基酸序列的BLAST比对,结果表明不同株系的Polh氨基酸序列高度同源,相似度达到99.94%;再以Bm NPV-T3株的143个开放阅读框序列为参照,对不同Bm NPV株系的基因组序列进行双序列比对,发现不同株系重复阅读框基因(bro)家族成员的组成、序列及拷贝数存在差异,且分布位置呈现多样性。初步认为,高度保守的polh基因可用于Bm NPV病毒的鉴定,而相对保守的bro家族基因可作为Bm NPV病毒株系分子鉴定的依据。

Bombyx mori nucleopoyhedrovirus（ Bm NPV） collected from different areas or sericultural regions have great difference in pathogenicity,showing obvious differentiation between various viral strains. The identification of epidemic Bm NPV strains is an important foundation for disease monitoring and controlling. BLAST analysis on polyhedrin gene（ polh） nucleotide sequence and its encoded amino acid sequence between the first sequenced Bm NPV-T3 strain and other six Bm NPV strains revealed that Polh sequence presented high homology among various strains. Their sequence identity was as high as 99. 94%. Pair-wise sequence alignment between 143 ORFs of Bm NPV-T3 and genomic sequences of other Bm NPV strains showed difference in bro（ a repeated ORF gene） family member composition,sequences and copy numbers among various strains. Different Bm NPV strains were diversified in genomic location of bro family members. This preliminary study suggests that the highly conserved polh gene can be used for identification of Bm NPV,and the relatively conserved bro family genes can be applied for identification of Bm NPV strains.