Muñoz D, Murillo R, Krell P J, Vlak J M, Caballero P
Departamento de Producción Agraria, Universidad Pública de Navarra, Pamplona, Spain.
Virus Res. 1999 Jan;59(1):61-74. doi: 10.1016/s0168-1702(98)00125-7.
Four genotypes named SP2A, SP2B, SP2C and SP2D were obtained in vivo by infecting S. exigua larvae with limiting dilutions of the Spanish field isolate Spodoptera exigua Nucleopolyhedrovirus (Se-SP2) of SeMNPV. The cloning of variants SP2A, SP2B and SP2C took 1, 6, and 3 passages, respectively, before the DNA profiles showed all bands in equimolar concentrations, and they remained constant for at least six further passages indicating the stability of their genotypes. The SP2D variant isolation took over ten passages and it was genetically less stable. Physical maps of their genomes were constructed for the restriction enzymes BamHI, BglII, PstI, and XbaI. The region between 8-10 m.u. was highly variable and characteristic of each cloned genotype and, hence, can be used as RFLP markers for all four genotypic variants. This region, included in the PstI-MB fragment, was cloned and sequenced showing that all the Se-SP2 variants contained a homologous region (hr) with a variable number of 98 bp sequences tandemly repeated, which were used to distinguish genotypic variants from each other. The biological activity of the genotypic variants SP2A, SP2B, and SP2C when compared in terms of LD50 and LT50, were not significantly different. However, the SP2D genotypic variant was found to be significantly less infective (higher LD50). The emergence of new genotypes in the Se-SP2 field populations is discussed.
通过用苜蓿银纹夜蛾核型多角体病毒（SeMNPV）的西班牙田间分离株苜蓿银纹夜蛾核型多角体病毒（Se - SP2）对甜菜夜蛾幼虫进行有限稀释感染，在体内获得了四种基因型，分别命名为SP2A、SP2B、SP2C和SP2D。在DNA图谱显示所有条带浓度等摩尔之前，变体SP2A、SP2B和SP2C的克隆分别经过了1、6和3代传代，并且在至少另外六代传代中它们保持不变，表明其基因型的稳定性。SP2D变体的分离经过了十多代传代，并且其遗传稳定性较低。构建了它们基因组针对限制性内切酶BamHI、BglII、PstI和XbaI的物理图谱。8 - 10个遗传单位之间的区域高度可变，是每个克隆基因型的特征，因此可以用作所有四种基因型变体的RFLP标记。包含在PstI - MB片段中的该区域被克隆并测序，结果表明所有Se - SP2变体都包含一个同源区域（hr），其中有可变数量的98 bp序列串联重复，这些序列用于区分不同的基因型变体。就LD50和LT50而言，基因型变体SP2A、SP2B和SP2C的生物活性没有显著差异。然而，发现SP2D基因型变体的感染力明显较低（LD50较高）。文中讨论了Se - SP2田间种群中新基因型的出现情况。
