Recombination in enteroviruses is a biphasic replicative process involving the generation of greater-than genome length 'imprecise' intermediates.
Recombination in enteroviruses is a biphasic replicative process involving the generation of greater-than genome length 'imprecise' intermediates.
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DOI：
10.1371/journal.ppat.1004191
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发表时间：
2014-06
期刊：
影响因子：
6.7
通讯作者：
Evans DJ
中科院分区：
文献类型：
--
作者：
Lowry K;Woodman A;Cook J;Evans DJ
肠道病毒中的重组提供了一种获得新序列的广泛区域的进化机制，被认为在基因型多样性中发挥作用，并且已知是脊髓灰质炎病毒新的神经病原变体出现的关键。尽管这种进化机制很重要，但人们对重组过程的了解仍然相对较少。我们使用一种新颖的反向遗传方法研究了异源重组，该方法导致分离出中间嵌合型间脊髓灰质炎病毒，其基因组在重组连接处具有大量重复序列。表现出这种不精确连接的病毒的连续传代产生了适应性增强的后代，但它们失去了重复的序列。改变聚合酶保真度或复制复合物聚结的突变或抑制剂显着改变了重组体的产量（但不影响非复制重组），表明该过程是复制性的，并且如果需要的话，有可能增强或减少重组介导的病毒进化。我们认为现有的重组体是由一个双相过程产生的，其中初始重组事件之后是一个解析过程，删除无关序列和优化病毒适应性。这一过程对于我们更广泛地理解正链 RNA 病毒的“复制进化”具有重要意义。大多数正义RNA病毒的快速进化使它们能够逃避免疫监视并适应新宿主。遗传变异的产生是由于它们的 RNA 聚合酶容易出错以及病毒基因组在共感染细胞中的重组。我们开发了一种新方法，使用脊髓灰质炎病毒模型系统来分析人们知之甚少的重组机制。我们对最初的可行重组体进行了表征，并证明由于不精确的交叉事件复制了部分基因组，大多数重组体都比基因组长度长。这些病毒是不适合的，但很快就会失去复制的材料，并在连续传代后恢复完全适合，我们称之为解决过程。我们通过修改病毒聚合酶或复制复合体聚结的保真度来证明这是一个复制重组过程，使用的方法对先前报道的、效率较低的非复制重组机制没有影响。我们得出的结论是，重组是一个双相过程，涉及单独的生成和分解事件。这些对重要进化机制的新见解对我们通过部分基因组复制理解病毒进化具有重要意义，它们提出了重组可能被修改的方法，并提供了一种可用于分析其他 RNA 病毒重组的方法。
Recombination in enteroviruses provides an evolutionary mechanism for acquiring extensive regions of novel sequence, is suggested to have a role in genotype diversity and is known to have been key to the emergence of novel neuropathogenic variants of poliovirus. Despite the importance of this evolutionary mechanism, the recombination process remains relatively poorly understood. We investigated heterologous recombination using a novel reverse genetic approach that resulted in the isolation of intermediate chimeric intertypic polioviruses bearing genomes with extensive duplicated sequences at the recombination junction. Serial passage of viruses exhibiting such imprecise junctions yielded progeny with increased fitness which had lost the duplicated sequences. Mutations or inhibitors that changed polymerase fidelity or the coalescence of replication complexes markedly altered the yield of recombinants (but did not influence non-replicative recombination) indicating both that the process is replicative and that it may be possible to enhance or reduce recombination-mediated viral evolution if required. We propose that extant recombinants result from a biphasic process in which an initial recombination event is followed by a process of resolution, deleting extraneous sequences and optimizing viral fitness. This process has implications for our wider understanding of ‘evolution by duplication’ in the positive-strand RNA viruses. The rapid evolution of most positive-sense RNA viruses enables them to escape immune surveillance and adapt to new hosts. Genetic variation arises due to their error-prone RNA polymerases and by recombination of viral genomes in co-infected cells. We have developed a novel approach to analyse the poorly understood mechanism of recombination using a poliovirus model system. We characterised the initial viable recombinants and demonstrate the majority are longer than genome length due to an imprecise crossover event that duplicates part of the genome. These viruses are unfit, but rapidly lose the duplicated material and regain full fitness upon serial passage, a process we term resolution. We show this is a replicative recombination process by modifying the fidelity of the viral polymerase, or replication complex coalescence, using methods that have no influence on a previously reported, less efficient, non-replicative recombination mechanism. We conclude that recombination is a biphasic process involving separate generation and resolution events. These new insights into an important evolutionary mechanism have implications for our understanding of virus evolution through partial genome duplication, they suggest ways in which recombination might be modified and provides an approach that may be exploited to analyse recombination in other RNA viruses.
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影响因子：
3.7
作者：
Duggal, R;Wimmer, E
通讯作者：
Wimmer, E
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3.7
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作者：
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