4个茶毛虫核型多角体病毒（EpNPV）分离株对茶毛虫的毒力测定结果表明,浙江分离株的毒力最强,其LC₅₀为2.5×10⁶PIB/mL;湖南分离株的毒力最弱,其LC₅₀为13.36×10⁶PIB/mL。不同分离株的毒力强弱依次为浙江分离株>贵州分离株>湖北分离株>湖南分离株,但贵州分离株与湖北分离株的毒力相差不大,LC₅₀分别为9.5×10⁶PIB/mL和7.31×10⁶PIB/mL。测定了EpNPV 4个分离株的5个与病毒复制、病毒—宿主关系、毒力水平相关的功能基因序列,分析其不同株系间的遗传结构,发现湖北分离株和贵州、湖南两分离株的相似度最高（99.7%）;浙江分离株和湖南分离株间的相似度最低（99.4%）。基于5个基因拼接序列构建的系统进化树显示,湖南（HN）和湖北（HB）两个株系最先聚类并为一支,再与贵州（GZ）分离株聚类,最后才与浙江分离株（ZJ）聚合,说明浙江分离株与其他3个分离株的遗传距离均较远。试验结果初步表明,EpNPV不同株系间的毒力水平差异与其遗传结构差异明显相关。

The virulence determination of four Euproctis pseudoconspersa nuclear polyhedrosis virus (EpNPV) isolates showed that Zhejiang isolate is the most toxic one (LC₅₀=2.50×10⁶PIB/mL), and Hunan isolate is the weakest isolate (LC₅₀=13.36×10⁶PIB/mL). The virulence of different isolates in order is Zhejiang (ZJ), Guizhou (GZ), Hubei (HB) and Hunan (HN), besides GZ and HB isolates have similar virulence, which LC₅₀ were 9.50×10⁶PIB/mL and 7.31×10⁶PIB/mL respectively. Five genes of the four isolates about virus reproduction, interaction between virus and host and virulence were determined and sequenced, genetic structure based on these genes among isolates was analysed, the result indicated the similarity of HB and GZ, HN are highest (99.7%), and that of ZJ between HN isolate are lowest (99.4%). The NJ and UPGMA phylogenetic trees based on five genes also showed that HB and HN isolates first clustered into one group, then clustered with GZ, finally clustered with ZJ isolate, which indicated that the genetic distance among ZJ and other three isolates are relatively far. Both virulence determination and genetic structure analysis suggested virulence and heredity among four virus isolates are closely related.