Centre of Biological Engineering, University of Minho, Braga, Portugal.
Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal.
Appl Environ Microbiol. 2019 Aug 14;85(17). doi: 10.1128/AEM.00934-19. Print 2019 Sep 1.
is emerging as a major nosocomial pathogen in intensive care units. The bacterial capsules are considered major virulence factors, and the particular capsular type K2 has been associated with high antibiotic resistance. In this study, we identified a K2 capsule-specific depolymerase in a bacteriophage tail spike C terminus, a fragment that was heterologously expressed, and its antivirulence properties were assessed by experiments. The K2 depolymerase is active under a broad range of environmental conditions and is highly thermostable, with a melting point ( ) at 67°C. In the caterpillar larva model, the K2 depolymerase protects larvae from bacterial infections, using either pretreatments or with single-enzyme injection after bacterial challenge, in a dose-dependent manner. In a mouse sepsis model, a single K2 depolymerase intraperitoneal injection of 50 μg is able to protect 60% of mice from an otherwise deadly infection, with a significant reduction in the proinflammatory cytokine profile. We showed that the enzyme makes bacterial cells fully susceptible to the host complement system killing effect. Moreover, the K2 depolymerase is highly refractory to resistance development, which makes these bacteriophage-derived capsular depolymerases useful antivirulence agents against multidrug-resistant infections. is an important nosocomial pathogen resistant to many, and sometimes all, antibiotics. The K2 capsular type has been associated with elevated antibiotic resistance. The capsular depolymerase characterized here fits the new trend of alternative antibacterial agents needed against multidrug-resistant pathogens. They are highly specific, stable, and refractory to resistance, as they do not kill bacteria ; instead, they remove bacterial surface polysaccharides, which diminish the bacterial virulence and expose them to the host immune system.
是一种新兴的重症监护病房主要医院病原体。细菌荚膜被认为是主要的毒力因子，而特定的荚膜类型 K2 与高抗生素耐药性有关。在这项研究中，我们在噬菌体尾部刺突 C 末端鉴定出一种 K2 荚膜特异性解聚酶，该片段被异源表达，并通过实验评估了其抗病毒特性。K2 解聚酶在广泛的环境条件下具有活性，并且具有高度的热稳定性，熔点（）为 67°C。在毛毛虫幼虫模型中，K2 解聚酶通过预处理或在细菌攻击后单次注射酶，以剂量依赖的方式保护幼虫免受细菌感染。在小鼠败血症模型中，单次腹腔注射 50μg 的 K2 解聚酶能够保护 60%的小鼠免受致命感染，显著降低促炎细胞因子谱。我们表明，该酶使细菌细胞完全易受宿主补体系统杀伤作用的影响。此外，该酶对耐药性发展具有高度抗性，这使得这些噬菌体衍生的荚膜解聚酶成为针对多药耐药感染的有用抗病毒药物。是一种重要的医院病原体，对许多甚至所有抗生素都有耐药性。K2 荚膜类型与升高的抗生素耐药性有关。这里描述的荚膜解聚酶符合针对多药耐药病原体所需的替代抗菌剂的新趋势。它们具有高度特异性、稳定性和耐药性，因为它们不会杀死细菌；相反，它们去除细菌表面多糖，从而降低细菌的毒力并使其暴露于宿主免疫系统。
