TOXINS OF BACTEROIDES FRAGILIS

脆弱拟杆菌毒素

• 批准号: 2672133
• 负责人: Tracy D. Wilkins
• 金额: $ 22.34万
• 依托单位: VIRGINIA POLYTECHNIC INST AND ST UNIV
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2672133
• 关键词: Bacteroides; bacterial cytopathogenic effect; bacterial genetics; bacterial proteins; basement membrane; brush border membrane; collagen; cytoskeletal proteins; diarrhea; enterotoxins; enzyme mechanism; immunocytochemistry; immunofluorescence technique; laminin; membrane proteins; metalloendopeptidases; molecular cloning; open reading frames; posttranslational modifications; proteolysis; receptor; second messengers; tight junctions; tissue /cell culture; western blottings

Bacteroides fragilis is a species of anaerobic bacteria which lives in the colon of humans and animals. It makes up only about 1% of the human colonic flora, however, it is the most commonly isolated anaerobe from abscesses and soft tissue infections. Recent reports have shown that certain strains of B. fragilis produce an enterotoxin, suggesting a new role for this organism as an enteropathogen as well as evidence for a new virulence factor involved in its pathogenicity in tissues. This toxin has been implicated as a cause of diarrhea in several species of farm animals and more recently in humans, particularly infants. In preliminary studies, it appears that about 10% of isolates produce the toxin, suggesting that it is present in the colon in many individuals over long periods of time. The activity of the toxin was first discovered in the mid-1980's using the ligated ileal loop assay in lambs. Then, in 1990, it was shown that the activity could be detected by tissue culture assay using HT-29 colon carcinoma cells. We have now purified the toxin to homogeneity and showed that the enterotoxic activity observed in the lamb ligated loop assay and the cytotoxic activity (i.e., rounding of HT-29 cells) is due to the same protein. We have characterized the toxin, which has an M of about 20,000 and determined a partial N-terminal amino acid sequence. We are now cloning and sequencing the toxin gene, and studying its receptors and mechanism of action. We are also making specific polyclonal and monoclonal antibodies against the toxin to develop specific ELISA assays for detecting the toxin in feces and other clinical samples. This will establish a firm base for future collaborations with clinical investigators to determine the role of this toxin in etiology of diarrheal and infectious diseases and to determine approaches to diagnosis, therapy and treatment.

细菌脆弱的是一种厌氧细菌，它生活在 人类和动物的结肠。 它仅占人类的1％ 然而，结肠植物群是最常见的厌氧菌 脓肿和软组织感染。 最近的报告表明 某些脆弱芽孢杆菌的菌株会产生一种肠毒素，这表明是新的 该生物作为肠病的作用以及新的证据 毒力因其在组织中的致病性涉及。 这种毒素具有 被认为是几种农场动物中腹泻的原因 最近在人类，尤其是婴儿。 在初步研究中， 看来约有10％的分离株产生毒素，表明它 在许多人长期存在于结肠中。 这 毒素的活性首先是在1980年代中期发现的 在羔羊中结扎的回肠循环测定法。 然后，在1990年，已经表明 使用HT-29结肠可以通过组织培养试验检测活性 癌细胞。 现在，我们已经将毒素纯化为均匀性并显示 在羔羊结扎的环测定中观察到的肠毒性活性和 细胞毒性活性（即HT-29细胞的圆形）是由于相同的 蛋白质。 我们已经表征了毒素，该毒素的M为20,000 并确定部分N末端氨基酸序列。 我们现在 克隆和测序毒素基因，并研究其受体和 作用机理。 我们还制作特定的多克隆和单克隆 针对毒素开发特定ELISA测定的抗体检测 粪便和其他临床样品中的毒素。 这将建立一个公司 将来与临床研究人员合作的基础，以确定 这种毒素在腹泻和传染病的病因中的作用以及 确定诊断，治疗和治疗的方法。