Lu A, Miller L K
Department of Entomology, The University of Georgia, Athens 30602, USA.
J Virol. 1996 Aug;70(8):5123-30. doi: 10.1128/JVI.70.8.5123-5130.1996.
The host cell-specific factor 1 gene (hcf-1) of the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) is required for the efficient replication and/or stability of reporter plasmids carrying an AcMNPV-derived origin of DNA replication in a cell-specific manner; hcf-1 is required for reporter plasmid replication or stability in TN-368 cells, a cell line derived from the cabbage looper Trichoplusia ni, but not in IPLB-SF-21 (SF-21) cells, a cell line derived from the fall armyworm Spodoptera frugiperda (A. Lu and L. K. Miller, J. Virol. 69:6265-6272, 1995). To further define the function of hcf-1, recombinant viruses with null mutations in hcf-1 were constructed in SF-21 cells and the phenotype of the mutants was determined in selected cell lines as well as in insect larvae. In S.frugiperda larvae and SF-21 cells, the phenotype of hcf-1 mutants was indistinguishable from that of wild-type AcMNPV. In T. ni larvae as well as T. ni-derived cell lines, hcf-1 mutants exhibited a mutant phenotype. In TN-368 cells, the replication of hcf-1 mutants was extremely impaired; the phenotype included a defect in viral DNA replication, late gene transcription, and virus production as well as a complete cessation of host and viral protein synthesis. In another cell line derived from T. ni, the BTI-TN5B1-4 cell line, the hcf-1 mutants exhibited a less severe phenotype. In T. ni larvae, the infectivity of the budded form of hcf-1 mutants was decreased significantly (50-fold), although no difference in the oral infectivity of the occluded form was observed. T. ni larvae infected with hcf-1 mutants by either oral or hemocoelic routes, however, died 20 to 30% more slowly than those infected with wild-type AcMNPV. These data indicate that there is a host-specific requirement for hcf-1 and that it exerts cell line-specific effects and possibly tissue-specific effects on the rate at which the virus replicates, thereby affecting the virulence of the virus in a species-specific manner.
苜蓿银纹夜蛾核型多角体病毒（AcMNPV）的宿主细胞特异性因子1基因（hcf - 1）对于携带AcMNPV来源的DNA复制起点的报告质粒以细胞特异性方式进行高效复制和/或维持稳定性是必需的；hcf - 1对于报告质粒在TN - 368细胞（一种源自甘蓝夜蛾粉纹夜蛾的细胞系）中的复制或稳定性是必需的，但对于IPLB - SF - 21（SF - 21）细胞（一种源自草地贪夜蛾的细胞系）则不是必需的（A. Lu和L. K. Miller，《病毒学杂志》69:6265 - 6272，1995年）。为了进一步确定hcf - 1的功能，在SF - 21细胞中构建了hcf - 1存在无效突变的重组病毒，并在选定的细胞系以及昆虫幼虫中测定了突变体的表型。在草地贪夜蛾幼虫和SF - 21细胞中，hcf - 1突变体的表型与野生型AcMNPV的表型没有区别。在粉纹夜蛾幼虫以及源自粉纹夜蛾的细胞系中，hcf - 1突变体表现出突变表型。在TN - 368细胞中，hcf - 1突变体的复制受到极大损害；其表型包括病毒DNA复制缺陷、晚期基因转录缺陷、病毒产生缺陷以及宿主和病毒蛋白合成完全停止。在另一种源自粉纹夜蛾的细胞系BTI - TN5B1 - 4细胞系中，hcf - 1突变体表现出的表型较轻。在粉纹夜蛾幼虫中，hcf - 1突变体的出芽形式的感染力显著降低（50倍），尽管未观察到包涵体形式的口服感染力有差异。然而，通过口服或血腔途径感染hcf - 1突变体的粉纹夜蛾幼虫比感染野生型AcMNPV的幼虫死亡速度慢20%至30%。这些数据表明，hcf - 1存在宿主特异性需求，并且它对病毒复制速率产生细胞系特异性影响，可能还产生组织特异性影响，从而以物种特异性方式影响病毒的毒力。
