Re-inventing pathogen passage for social microbes
Re-inventing pathogen passage for social microbes
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DOI：
10.1101/2022.08.04.502769
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
T. Dimitriu;Wided Souissi;Peter Morwool;A. Darby;N. Crickmore;B. Raymond
中科院分区：
文献类型：
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作者：
T. Dimitriu;Wided Souissi;Peter Morwool;A. Darby;N. Crickmore;B. Raymond
用寄生虫连续感染宿主的传代实验长期以来一直被用来操纵毒力。然而，在许多无脊椎动物病原体中，传代一直被天真地应用，而没有对如何最好地选择以增加毒力的充分理论理解。这导致了非常复杂的结果。了解毒力的演变是复杂的，因为选择寄生虫发生在多个空间尺度上，可能存在不同的冲突，对不同生活史的寄生虫起作用。例如，在社会性微生物中，宿主对复制率的强选择会导致欺骗和毒力的丧失，因为对公共产品毒力的投资会降低复制率。相反，选择作用于宿主之间的规模通过选择寄生虫种群大小来维持毒力。在这项研究中，我们测试了不同规模的选择和不同的突变供应如何影响专业昆虫病原体苏云金芽孢杆菌对抗性宿主的毒力进化。旨在优化针对难以杀死的昆虫靶标的菌株改良方法。我们表明，选择感染性使用亚群之间的竞争，防止社会欺骗，行为保留关键的毒力质粒，并促进增加毒力。增加的毒力与孢子形成效率降低，并在假定的调控基因的功能丧失，但不与已知的毒力因子的表达改变。集合种群中的选择提供了一种广泛适用的工具，用于提高生物防治剂的功效。此外，结构化的宿主种群可以促进对感染性的人工选择，而对生活史特征的选择，如更快的复制或更大的种群规模可以降低毒性。
Passage experiments that sequentially infect hosts with parasites have long been used to manipulate virulence. However, in many invertebrate pathogens passage has been applied naively without a full theoretical understanding of how best to select for increased virulence. This has led to very mixed results. Understanding the evolution of virulence is complex because selection on parasites occurs across multiple spatial scales with potentially different conflicts operating on parasites with different life-histories. For example, in social microbes, strong selection on replication rate within hosts can lead to cheating and loss of virulence, because investment in public goods virulence reduces replication rate. In contrast, selection acting at a between host scale maintains virulence by selecting on parasite population size. In this study we tested how different scales of selection and varying mutation supply affect evolution of virulence against resistant hosts in the specialist insect pathogen Bacillus thuringiensis., aiming to optimize methods for strain improvement against a difficult to kill insect target. We show that selection for infectivity using competition between sub-populations in a metapopulation prevents social cheating, acts to retain key virulence plasmids and facilitates increased virulence. Increased virulence was associated with reduced efficiency of sporulation, and loss of function in putative regulatory genes but not with altered expression of known virulence factors. Selection in a metapopulation provides a broadly applicable tool for improving the efficacy of biocontrol agents. Moreover, a structured host population can facilitate artificial selection on infectivity, while selection on life history traits such as faster replication or larger population sizes can reduce virulence can reduce virulence in social microbes.