Evans David Hugh
Department of Medical Microbiology & Immunology and Li Ka Shing Institute of Virology, The University of Alberta, Edmonton, AB T6G 2J7, Canada.
Pathogens. 2022 Aug 9;11(8):896. doi: 10.3390/pathogens11080896.
Genetic recombination is used as a tool for modifying the composition of poxvirus genomes in both discovery and applied research. This review documents the history behind the development of these tools as well as what has been learned about the processes that catalyze virus recombination and the links between it and DNA replication and repair. The study of poxvirus recombination extends back to the 1930s with the discovery that one virus can reactivate another by a process later shown to generate recombinants. In the years that followed it was shown that recombinants can be produced in virus-by-virus crosses within a genus (e.g., variola-by-rabbitpox) and efforts were made to produce recombination-based genetic maps with modest success. The marker rescue mapping method proved more useful and led to methods for making genetically engineered viruses. Many further insights into the mechanism of recombination have been provided by transfection studies which have shown that this is a high-frequency process associated with hybrid DNA formation and inextricably linked to replication. The links reflect the fact that poxvirus DNA polymerases, specifically the vaccinia virus E9 enzyme, can catalyze strand transfer in in vivo and in vitro reactions dependent on the 3'-to-5' proofreading exonuclease and enhanced by the I3 replicative single-strand DNA binding protein. These reactions have shaped the composition of virus genomes and are modulated by constraints imposed on virus-virus interactions by viral replication in cytoplasmic factories. As recombination reactions are used for replication fork assembly and repair in many biological systems, further study of these reactions may provide new insights into still poorly understood features of poxvirus DNA replication.
在发现和应用研究中，基因重组都被用作一种修饰痘病毒基因组组成的工具。这篇综述记录了这些工具发展背后的历史，以及我们对催化病毒重组的过程、它与DNA复制和修复之间的联系的了解。痘病毒重组的研究可以追溯到20世纪30年代，当时发现一种病毒可以通过后来被证明能产生重组体的过程重新激活另一种病毒。在随后的几年里，人们发现重组体可以在同一属内的病毒与病毒杂交中产生（例如，天花病毒与兔痘病毒杂交），并努力制作基于重组的遗传图谱，但取得的成功有限。标记拯救定位方法被证明更有用，并导致了制造基因工程病毒的方法。转染研究提供了许多关于重组机制的进一步见解，这些研究表明这是一个与杂交DNA形成相关的高频过程，并且与复制有着千丝万缕的联系。这些联系反映了这样一个事实，即痘病毒DNA聚合酶，特别是牛痘病毒E9酶，能够在体内和体外反应中催化链转移，这种反应依赖于3'至5'校对核酸外切酶，并由I3复制性单链DNA结合蛋白增强。这些反应塑造了病毒基因组的组成，并受到细胞质工厂中病毒复制对病毒-病毒相互作用施加的限制的调节。由于重组反应在许多生物系统中用于复制叉组装和修复，对这些反应的进一步研究可能会为人们对痘病毒DNA复制中仍知之甚少的特征提供新的见解。
