本文从形态结构、生物活性、结构多肽、核酸限制性内切酶图谱和核酸同源性等方面对棉铃虫核型多角体病毒四个分离株（两个ＳＮＰＶ分离株：ＨａＳ、ＨｚＳ，和两个ＭＮＰＶ分离株：ＨａＭ１、ＨａＭ２）进行了比较研究。它们对中国棉铃虫二龄末三龄初幼虫的ＬＤ５０佰依次为３６１、３８７、２６３３、３５６０ＰＩＢｓ／克饲料，当感染剂过为５×ｌ０３ＰＩＢｓ／克饲料时，其ＬＴ５０值依次为４．６、４．９、６．４和６．６天。两个ＳＮＰＶ分离株的生物活性显著高于两个ＭＮＰＶ分离株。经ＳＤＳ－ＰＡＧＥ分析，四个分离株多角体蛋白均为一条带，两个ＭＮＰＶ分离株结构多肽均具有相同的迁移率，两个ＳＮＰＶ分离株的结构多肽图谱也颇相似，但ＳＮＰＶ与ＭＮＰＶ分离株之间带型相差较大。各分离株基出组经ＢａｍＨＩ、ＥｃｏＲＩ、ＨｉｎｄⅢ和ＸｂａＩ消化后，得到的内切酶图谱表现为两个ＮＭＰＶ分离株一致，两个ＳＮＰＶ分离株也很相似，而ＳＮＰＶ与ＭＮＰＶ分离株之间相差很大。严格条件杂交结果表明：两个ＳＮＰＶ分离株的基因组有较高的同源性，而ＳＮＰＶ与ＭＮＰＶ基因组之间的同源性极低。

our Heliothis NPV isolates(two SNPV:HaS and HzS two MNPVs:HaMl and HaM2)were com-pared on the shape and structure,biological activity,structural polypeptide,restriction pattern andDNA homology.The LD50 values of the four isolates for late second to early third instar H.armigera larvae were 361,387,2633 and 3560 PIBs/g of diet;the LT50 valuse for 5×103 PIBs/g of diet were4.6,4.9,6.4 and 6.6 days respectively,Bioactivities of two SNPV isolates were higlier than that of two MNPV isolates.Assayed by SDS-PAGE,each polyhedrin of four isolates contained a singlepolypoptide.The structural polypeptides of HaM1 HaM2 comigated on SDS-gels,the strueturalpolypeptide maps of Has and HzS were similar,but there were little similarity between SNPV and MNPV structural polypeptides,Digested by BamHI、EcoRI、HindⅢ and XbaI,two MNPV genomes hadidentieal restriction patterns,and two SNPV genomes had similar fragmentation profiles,showing onlyslight difference in the number and size of several fragments.But SNPV and MNPV genomes had