Analysis of the molecular mechanisms of host range determination of nucleopolyhedovirus

分别将加利福尼亚自拟虫（Ac）、家蚕（Bm）、加利福尼亚棘球蚴（Hc）和斑点Spodoptera exigua （Se）核多角体病毒（npv）接种到sf21细胞、BmN-4细胞、SpIm细胞和Se301细胞上，比较观察接种细胞的细胞病变效应（CPE）表现、病毒DNA的产生、在培养基中添加病毒粒子的产量、病毒结构蛋白的产生、多面体的基质蛋白（polyhedrin）的产生和多面体的形成。结果表明，AcNPV在4种细胞系中均能增殖并产生出芽病毒粒子，但只在sf21细胞、SpIm细胞和Se301细胞中产生多面体和多面体，而在BmN-4细胞中不产生多面体。BmN-4细胞BmNPV呈高滴度增殖，而SpIm细胞BmNPV呈低滴度增殖，只有少数细胞表现为CPE。BmNPV接种SF21和Se301细胞未见明显CPE。HcNPV在SpIm和Se301细胞中明显增殖并产生多面体。在SF21细胞中，HcNPV只产生低滴度的出芽病毒粒子，既不产生多面体，也不产生多面体。在hcnpv接种的BmN-4细胞中，大量的病毒DNA积累，但没有检测到病毒结构蛋白和多面蛋白的积累和出芽病毒粒子的产量。SeNPV仅在Se301细胞中明显增殖，并在SpIm培养的许多细胞中诱导凋亡形式的细胞死亡。这些结果表明，NPV在细胞中表现出复杂的特征，这取决于NPV的种类和接种的培养细胞，为分析NPV宿主范围的分子机制奠定了重要的基础。

Autographa californica (Ac), Bombyx mori (Bm), Hyphantria cunea (Hc) and Spodoptera exigua (Se) nucleopolyhedroviruses (NPVs) were each inoculated to SF21cells, BmN-4 cells, SpIm cells and Se301 cells, and cytopathic effect (CPE) manifestation, viral DNA production, badded virion yield into the culture medium, viral structural protein production, polyhedrin (the matrix protein of polyhedra) production, and polyhedron formation in the inoculated cells were comparatively examined. The results showed that AcNPV were able to multiply and yield budded virions in all of four cell lines examined, but production of polyhedrin and polyhedra occurred only SF21cells, SpIm cells and Se301 cells, and not in BmN-4 cells.BmNPV multiplied to a high titre in BmN-4 cells and to a low titre in SpIm cells in which only a few number of cells manifested CPE.No clear CPE was observed in SF21 and Se301 cells inoculated with BmNPV.HcNPV multiplied unequivocally and produced polyhedra in SpIm and Se301 cells. In SF21 cells, HcNPV yielded budded virions only to a low titre and produced neither polyhedrin nor polyhedra. In HcNPV-inoculated BmN-4 cells, significant amount of viral DNA accumulated, but accumulation of viral structural protein and polyhedrin and budded virion yield were never detected. SeNPV multiplied clearly only in Se301 cells, and appeared to induce apoptotic form of cell death in many cells of SpIm culture.These results indicate that NPVs exhibit complex feature in the cells depending upon both the species of NPV and cultured cells being inoculated, and establish important basis for the analysis of molecular mechanisms of host range determination in NPVs.