BcpAIOB-Mediated CDI and Biofilm Formation in Burkholderia pseudomallei

描述(申请人提供)：假性伯克霍尔德氏菌是一种能动的、革兰氏阴性的环境腐生菌，是一种新出现的传染病问题，也是以前武器化的疾控中心一级选择剂。它会在人类中引起类鼻疽病，如果不治疗，这种疾病在急性情况下可能在几天内致命。虽然地方性分布于东南亚和澳大利亚北部，但有证据表明，假鼻疽杆菌正在超越既定的边界传播。缺乏疫苗和快速诊断测试，再加上这种细菌的低感染剂量和内在的抗生素耐药性，突显出需要开发新的疗法和新的战略，从受污染的环境中消除假鼻疽杆菌，假鼻疽杆菌是唯一向人类传播的宿主。接触依赖生长抑制(CDI)是一种细菌在细胞与细胞接触时利用暴露在细胞表面的大型外源蛋白的有毒C末端来抑制邻近细菌的生长的现象。如果存在于细胞质中，免疫蛋白就会与有毒多肽结合，阻止它们的催化活性，防止细胞死亡。CDI系统外源蛋白和免疫蛋白的毒性C末端是多态的，免疫蛋白以等位基因特异性的方式保护机体免受CDI的侵袭。有人认为，这种多态允许细菌使用CDI系统来区分自我和异体，作为微生物群落中亲缘选择的一种机制，但这一假设尚未得到检验。是否存在不同CDI系统的潜力等级，以及拥有多个CDI系统是否有利，也没有进行过测试。我们建议进行实验，以确定假鼻疽杆菌中的bcpAIOB基因是否如预测的那样编码介导假鼻疽杆菌中细菌间竞争和生物膜形成的蛋白质。我们将确定不同的bcpAIOB等位基因是否编码具有不同效力的蛋白质，以及拥有多个等位基因是否会带来竞争优势。我们还将确定是否发生种间CDI，以及是否可以对与假鼻疽杆菌生活在同一生态位中的非病原体泰兰伯克霍尔德氏菌进行改造，以产生多个CDI系统，以及这种菌株是否能够与假鼻疽杆菌竞争，防止或破坏假鼻疽杆菌的生物被膜。我们的结果将为CDI系统的开发奠定基础 用作净化剂，也有可能用作治疗药物。

DESCRIPTION (provided by applicant): Burkholderia pseudomallei, a motile, Gram-negative, environmental saprotroph, is an emerging infectious disease problem and a previously-weaponinzed CDC Tier 1 select agent. It causes melioidosis in humans, which, in its acute form, can be fatal within days if untreated. Although endemic to southeast Asia and northern Australia, there is evidence that B. pseudomallei is spreading beyond established boundaries. Lack of a vaccine and lack of rapid diagnostic tests, together with the bacterium's low infectious dose and intrinsic antibiotic resistance, underscore the need to develop new therapeutics and new strategies for eliminating B. pseudomallei from contaminated environments, the only reservoir from which transmission to humans occurs. Contact-Dependent Growth Inhibition (CDI) is a phenomenon in which bacteria use the toxic C-terminus of a large surface-exposed exoprotein to inhibit the growth of neighboring bacteria upon cell-cell contact. If present in the cytoplasm, immunity proteins bind to the toxic polypeptides, blocking their catalytic activity and preventing cell death. The toxic C-termini of CDI system exoproteins and the immunity proteins are polymorphic and immunity proteins protect against CDI in an allele-specific manner. It has been suggested that this polymorphism allows bacteria to use CDI systems to discriminate self from non-self as a mechanism for kin selection in microbiological communities, but this hypothesis has not been tested. Whether there is a hierarchy of potencies of different CDI systems and whether the possession of multiple CDI systems is advantageous have also not been tested. We propose experiments to determine if bcpAIOB genes in B. pseudomallei do, as predicted, encode proteins that mediate interbacterial competition and biofilm formation in B. pseudomallei. We will determine if different bcpAIOB alleles encode proteins with different potencies, and if possession of multiple alleles confers a competitive advantage. We will also determine if inter-species CDI occurs and if Burkholderia thailandensis, a non-pathogen that lives in the same ecological niche as B. pseudomallei, can be engineered to produce multiple CDI systems and if this strain can out-compete B. pseudomallei and prevent or destroy B. pseudomallei biofilms. Our results will form the foundation for the exploitation of CDI systems for use as decontaminants and, potentially, therapeutics.