Nuss D L
Department of Molecular Oncology & Virology, Roche Research Center, Nutley, New Jersey 07110.
Microbiol Rev. 1992 Dec;56(4):561-76. doi: 10.1128/mr.56.4.561-576.1992.
Environmental concerns have focused attention on natural forms of disease control as potentially safe and effective alternatives to chemical pesticides. This has led to increased efforts to develop control strategies that rely on natural predators and parasites or that involve genetically engineered microbial pest control agents. This review deals with a natural form of biological control in which the virulence of a fungal pathogen is attenuated by an endogenous viral RNA genetic element: the phenomenon of transmissible hypovirulence in the chestnut blight fungus, Cryphonectria parasitica. Recent progress in the molecular characterization of a hypovirulence-associated viral RNA has provided an emerging view of the genetic organization and basic expression strategy of this class of genetic elements. Several lines of evidence now suggest that specific hypovirulence-associated virus-encoded gene products selectively modulate the expression of subsets of fungal genes and the activity of specific regulatory pathways. The construction of an infectious cDNA clone of a hypovirulence-associated viral RNA represents a major advancement that provides exciting new opportunities for examining the molecular basis of transmissible hypovirulence and for engineering hypovirulent strains for improved biocontrol. These developments have significantly improved the prospects of using this system to identify molecular determinants of virulence and elucidate signal transduction pathways involved in pathogenic responses. In addition, novel approaches are now available for extending the application of transmissible hypovirulence for management of chestnut blight and possibly other fungal diseases.
环境问题已将人们的注意力集中到自然疾病控制形式上，它们作为化学农药潜在的安全有效替代品。这促使人们加大力度开发依赖自然捕食者和寄生虫的控制策略，或涉及基因工程微生物害虫控制剂的策略。本综述探讨了一种自然生物控制形式，其中真菌病原体的毒力被一种内源性病毒RNA遗传元件减弱：栗疫病菌（Cryphonectria parasitica）中可传播的低毒力现象。与低毒力相关的病毒RNA分子特征的最新进展，为这类遗传元件的遗传组织和基本表达策略提供了新的见解。现在有几条证据表明，特定的与低毒力相关的病毒编码基因产物选择性地调节真菌基因子集的表达和特定调控途径的活性。构建与低毒力相关的病毒RNA的感染性cDNA克隆是一项重大进展，为研究可传播低毒力的分子基础以及改造低毒力菌株以改善生物防治提供了令人兴奋的新机会。这些进展显著改善了利用该系统鉴定毒力分子决定因素并阐明致病反应中涉及的信号转导途径的前景。此外，现在有了新的方法来扩展可传播低毒力在栗疫病以及可能其他真菌病害管理中的应用。
