A modified R-type bacteriocin specifically targeting Clostridium difficile prevents colonization of mice without affecting gut microbiota diversity.
A modified R-type bacteriocin specifically targeting Clostridium difficile prevents colonization of mice without affecting gut microbiota diversity.
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DOI：
10.1128/mbio.02368-14
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发表时间：
2015-03-24
期刊：
影响因子：
6.4
通讯作者：
Govoni GR
中科院分区：
文献类型：
--
作者：
Gebhart D;Lok S;Clare S;Tomas M;Stares M;Scholl D;Donskey CJ;Lawley TD;Govoni GR
艰难梭菌是全球医院感染的主要原因，并已成为一个紧迫的公共卫生威胁，需要立即关注。在过去十年中，BI/NAP 1/027菌株类型的流行性谱系已经出现并通过地球仪的卫生保健系统传播。限制人与人之间的传播和从医疗机构根除艰难梭菌，特别是BI/NAP 1/027菌株类型，是困难的，因为大多数干预措施都无法阻止孢子的大量脱落。缺乏对艰难梭菌感染（CDI）的有效预防。为此，我们对来自艰难梭菌菌株CD 4的收缩性R型细菌素（“艰难梭菌素”）进行了遗传修饰，以杀死BI/NAP 1/027型菌株。将负责艰难梭菌素靶向的天然受体结合蛋白（RBP）替换为通过基因组挖掘在BI/NAP 1/027型靶菌株的原噬菌体内鉴定的新发现的RBP。将所得的经修饰的艰难梭菌素（a.k.a. Avidocin-CD）、Av-CD 291.1和Av-CD 291.2是稳定的，并且杀死所有16个测试的BI/NAP 1/027型菌株。在饮用水中施用的Av-CD 291.2在通过小鼠胃肠道（GI）道时存活，没有可检测地改变小鼠肠道微生物群或破坏对艰难梭菌或万古霉素抗性屎肠球菌（VREF）的天然定殖抗性，并且防止用BI/NAP 1/027型孢子接种的小鼠的抗生素诱导的定殖。鉴于病原体的高发病率和毒力，预防BI/NAP 1/027型菌株的定殖并限制其传播可显著降低最严重CDI的发生率。这种经修饰的艰难梭菌素代表了Avidocin-CD平台的原型，该平台能够产生可靶向的、精确的抗艰难梭菌剂，该抗艰难梭菌剂可以预防和潜在地治疗CDIs，而不破坏保护性的固有微生物群。细菌性疾病的治疗和预防策略严重依赖传统抗生素，这些抗生素对耐药性进行了强有力的选择，并破坏了保护性微生物群。一个后果是机会致病菌的激增，如艰难梭菌，它们利用肠道微生物群中的益生菌诱导的破坏来增殖并导致危及生命的疾病。我们已经开发了利用收缩性杀菌蛋白复合物（R型细菌素）杀死特定艰难梭菌病原体的替代剂。在临床前动物研究中的功效表明，这些分子值得进一步开发作为预防人类艰难梭菌感染的潜在预防剂。由于这些药物不会显著改变小鼠体内固有的肠道微生物群或定植抗性，因此我们认为它们可以安全地作为预防剂给药，以阻断高风险环境中的传播，而不会使患者在停止治疗后易受肠道感染。
Clostridium difficile is a leading cause of nosocomial infections worldwide and has become an urgent public health threat requiring immediate attention. Epidemic lineages of the BI/NAP1/027 strain type have emerged and spread through health care systems across the globe over the past decade. Limiting person-to-person transmission and eradicating C. difficile, especially the BI/NAP1/027 strain type, from health care facilities are difficult due to the abundant shedding of spores that are impervious to most interventions. Effective prophylaxis for C. difficile infection (CDI) is lacking. We have genetically modified a contractile R-type bacteriocin (“diffocin”) from C. difficile strain CD4 to kill BI/NAP1/027-type strains for this purpose. The natural receptor binding protein (RBP) responsible for diffocin targeting was replaced with a newly discovered RBP identified within a prophage of a BI/NAP1/027-type target strain by genome mining. The resulting modified diffocins (a.k.a. Avidocin-CDs), Av-CD291.1 and Av-CD291.2, were stable and killed all 16 tested BI/NAP1/027-type strains. Av-CD291.2 administered in drinking water survived passage through the mouse gastrointestinal (GI) tract, did not detectably alter the mouse gut microbiota or disrupt natural colonization resistance to C. difficile or the vancomycin-resistant Enterococcus faecium (VREF), and prevented antibiotic-induced colonization of mice inoculated with BI/NAP1/027-type spores. Given the high incidence and virulence of the pathogen, preventing colonization by BI/NAP1/027-type strains and limiting their transmission could significantly reduce the occurrence of the most severe CDIs. This modified diffocin represents a prototype of an Avidocin-CD platform capable of producing targetable, precision anti-C. difficile agents that can prevent and potentially treat CDIs without disrupting protective indigenous microbiota. Treatment and prevention strategies for bacterial diseases rely heavily on traditional antibiotics, which impose strong selection for resistance and disrupt protective microbiota. One consequence has been an upsurge of opportunistic pathogens, such as Clostridium difficile, that exploit antibiotic-induced disruptions in gut microbiota to proliferate and cause life-threatening diseases. We have developed alternative agents that utilize contractile bactericidal protein complexes (R-type bacteriocins) to kill specific C. difficile pathogens. Efficacy in a preclinical animal study indicates these molecules warrant further development as potential prophylactic agents to prevent C. difficile infections in humans. Since these agents do not detectably alter the indigenous gut microbiota or colonization resistance in mice, we believe they will be safe to administer as a prophylactic to block transmission in high-risk environments without rendering patients susceptible to enteric infection after cessation of treatment.