In vivo exposure of insect AMP resistant Staphylococcus aureus to an insect immune system
In vivo exposure of insect AMP resistant Staphylococcus aureus to an insect immune system
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DOI：
10.1016/j.ibmb.2019.04.017
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发表时间：
2019-07-01
影响因子：
3.8
通讯作者：
Rolff, Jens
中科院分区：
文献类型：
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作者：
El Shazely, Baydaa;Urabanski, Arkadiusz;Rolff, Jens
抗菌肽（Antimicrobial Peptides，AMP）是昆虫体内重要的免疫效应物质。细菌抵抗AMP的方法有限，而且AMP抗性通常代价高昂。最近，已经清楚AMP在体外和体内的活性不同。尽管一些研究已经追踪了AMP抗性病原体的体内存活，但研究对该特定宿主的AMP具有抗性的病原体从未报道过。在这里，我们用金黄色葡萄球菌菌株感染黄粉虫甲虫黄粉虫，金黄色葡萄球菌菌株是在体外存在一种或两种来自T.莫利托。我们发现，黄粉虫的免疫系统可以清除突变的Tenecin耐药菌株至少有效敏感的控制。耐Tenecin的S.金黄色葡萄球菌通过突变分离。在pmt和rpo操纵子中具有突变的菌株显示出最高的体内存活率，因此在进化的抗性突变中显示出最低的适应性成本。相比之下，在nsa和rpo操纵子中具有突变的Tenecin抗性菌株在宿主中的存活率要低得多。我们的研究表明，Tenecin耐药菌株以较低的速率被吞噬。nsa/rpo突变体的吞噬率高于其他Tenecin抗性S.金黄色葡萄球菌抗AMP和吞噬作用的差异并没有转化为毒力的变化。AMP抗性虽然是脊椎动物感染的先决条件，但并不为S.金黄色葡萄球菌在由AMP主导的宿主环境中。
Antimicrobial peptides (AMPs) are important immune effectors in insects. Bacteria have a limited number of ways to resist AMPs, and AMP-resistance is often costly. Recently, it has become clear that AMP activities in vitro and in vivo differ. Although some studies have followed the in vivo survival of AMP resistant pathogens, studying a pathogen resistant to the AMPs of that particular host has never been reported. Here, we infected the mealworm beetle Tenebrio molitor with Staphylococcus aureus strains that were evolved in vitro in the presence of one or two antimicrobial peptides from T. molitor. We found that the Tenebrio immune system could clear mutant Tenecin resistant strains at least as efficiently as sensitive controls. The bacterial load of Tenecin resistant S. aureus segregated by mutation. Strains with mutations in both the pmt and rpo operons showed the highest in vivo survival and therefore showed the lowest fitness cost amongst the evolved resistance mutations. In contrast, Tenecin resistant strains with mutations in the nsa and rpo operons showed much lower survival within the hosts. Our study shows that Tenecin resistant strains are phagocytosed at a lower rate. The nsa/rpo mutants were phagocytosed at a higher rate than other Tenecin resistant S. aureus strains. The differences in resistance against AMPs and phagocytosis did not translate into changes in virulence. AMP resistance, while a prerequisite for an infection in vertebrates, does not provide a survival advantage to S. aureus in a host environment that is dominated by AMPs.