Origin of Virulence Factors in African Trypanosomes

非洲锥虫毒力因子的起源

• 批准号: 6599933
• 负责人: ANDREW G MCARTHUR
• 金额: $ 7.75万
• 依托单位: MARINE BIOLOGICAL LABORATORY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6599933
• 关键词: Trypanosoma brucei rhodesiense; cellular immunity; computer program /software; gene expression; genetic regulation; haptoglobins; host organism interaction; immunogenetics; messenger RNA; microorganism culture; molecular cloning; nucleic acid sequence; polymerase chain reaction; protein structure function; serial analysis of gene expression; transfection; virulence

DESCRIPTION (provided by the applicant): Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense are protozoan parasites that cause African sleeping sickness in humans while Trypanosoma brucei brucei causes a wasting disease in cattle called Nagana. These parasites are morphologically indistinguishable and the only clear phenotypic distinction is the inability of T. b. brucei to infect humans. Innate protection against T. b. brucei infection is mediated by Trypanosome Lytic Factors (TLF) found in the serum of humans, apes and old-world monkeys. The active component of TLF is the primate specific haptoglobin related protein (HPR). This protein is the sole factor preventing infection of humans by T. b. brucei, thus severely restricting its host range. The human sleeping sickness trypanosomes, T. b. rhodesiense and T. b. gambiense, are able to infect humans due to their resistance to the cytotoxic action of HPR. Analysis of human infectious and non-infectious lines of T. b. rhodesiense resulted in the identification of a trypanosome gene what is necessary for human infection. The serum resistance associated (SRA) gone is highly conserved in T. b. rhodesiense isolates and is a member of the variant surface glycoprotein (VSG) superfamily. The SRA gene is absent in T. b. brucei, although similar gene sequences are present. To define the mechanism of human infectivity, we have selected for T. b. brucei lines resistant to TLF. The TLF resistant lines of T. b. brucei are able to avoid the cytotoxicity of HPR despite lacking the SRA gene. Examination of genome-wide gene expression patterns in TLF susceptible and resistant 7-.b. brucei lines will provide a coherent picture of the biological pathways in trypanosomes that influence host range and human infection. As the genome sequence of T. b. brucei is largely complete and we have been able to select for isogenic lines of T. b. brucei with differing degrees of susceptibility to TLF in vitro, we propose to utilize Serial Analysis of Gene Expression (SAGE) to monitor genome-wide levels of mRNA expression associated with human virulence. To detect regulation of genes related to human infectivity, we will perform SAGE by generating approximately 14,000 21 bp sequence tags from the mRNA of 10 isogenic lines of T. b. brucei (427 strain) differing in level of resistance to TLF. This research will provide a comprehensive understanding of changes in trypanosome gene expression in response to selective pressure of human innate immunity and will provide clues as to the origin of the SRA gene.

描述（由申请人提供）：Brucei gambiense和Brucei Rhodesiense的锥虫瘤是原生动物的寄生虫，引起人类的非洲睡眠疾病，而Brucei Brucei Brucei Brucei则导致牛的浪费，称为Nagana。这些寄生虫在形态上是无法区分的，唯一的明确表型区别是T. b的无能为力。布鲁氏感染人类。对T. b的先天保护。 Brucei感染是由人类，猿和旧世界猴子血清中发现的锥虫裂解因子（TLF）介导的。 TLF的活性成分是灵长类动物特异性触觉相关蛋白（HPR）。该蛋白是防止人类感染的唯一因素。 Brucei，因此严重限制了其宿主范围。人类睡病锥虫，T。B。 Rhodesiense和T. b。 Gambiense，由于人类对HPR的细胞毒性作用的抗性，能够感染人类。 分析T. b的人类感染和非感染线。 Rhodesiense导致鉴定锥体基因人类感染所需的内容。在T. b中，相关的血清耐药性（SRA）消失了。 Rhodesiense分离株，是变体表面糖蛋白（VSG）超家族的成员。 T. b中不存在SRA基因。 Brucei，尽管存在相似的基因序列。为了定义人类感染的机制，我们选择了T. b。 Brucei线对TLF具有抗性。 T. b的TLF抗线。尽管缺乏SRA基因，但布鲁西仍能够避免HPR的细胞毒性。在TLF易感和抗性7-.b中检查全基因组基因表达模式。 Brucei线将在影响宿主范围和人类感染的锥虫中提供一致的生物途径。作为T. b的基因组序列。 Brucei在很大程度上是完整的，我们已经能够选择T。b的等源线。在体外对TLF的敏感性不同程度的Brucei，我们建议利用基因表达（SAGE）的系列分析来监测与人类毒力相关的全基因组mRNA表达水平。为了检测与人类感染性相关的基因的调节，我们将通过从T. b的10个同基因线的mRNA产生大约14,000 21 bp序列标签来执行鼠尾草。 Brucei（427菌株）在对TLF的抗性水平上不同。这项研究将对人类先天免疫的选择性压力响应锥虫基因表达的变化提供全面的理解，并将提供有关SRA基因起源的线索。