INTERSPECIFIC COMPETITION BETWEEN RICKETTSIAE IN TICKS

蜱中立克次体之间的种间竞争

• 批准号: 6163943
• 负责人: Abdu F Azad
• 金额: $ 18.52万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-03-01 至 2003-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6163943
• 关键词: Ixodes; Rickettsia; Rocky Mountain spotted fever; SDS polyacrylamide gel electrophoresis; arthropod borne communicable disease; bioassay; comorbidity; density gradient ultracentrifugation; disease vectors; electron microscopy; epizootiology; host organism interaction; immunocytochemistry; intracellular transport; laboratory mouse; polymerase chain reaction; restriction fragment length polymorphism; southern blotting; virulence; western blottings

In nature, individual ticks can be concomittently infected with more than one species of intracellular bacteria. Some may be important human pathogens acquired either from an infectious bloodmeal or transovarially. Others may be nonpathogenic symbionts acquired transovarially. The consequences and epidemiological significance of multiple bacterial infections in ticks are largely unexplored. We propose that the interactive effects between certain intracellular bacterial species within individual ticks may be of sufficient prevalence and magnitude to alter the vector competence of ticks. Ovaries of Dermacentor andersoni ticks harboring a particular nonpathogenic species of spotted fever group rickettsia, namely Rickettsia peacockii, have been shown to be refractory to subsequent co- infection with otherwise invasive R. rickettsii. Thus, ovarial infection of D. andersoni with R. peacockii rickettsiae interferes or blocks normal transovarial transmission of R. rickettsii. Infections with two or more closely-related rickettsial species may result either in interference (i.e., one species inhibits the development and/or transmission of the other), mutualism (i.e., enhanced transmission of both species), or phenotypic mixing (i.e., increased or decreased virulence). This proposal specifically addresses transovarial interference of the human pathogen, Rickettsia rickettsii, in the tick vector transovarially infected with nonpathogenic rickettsiae. We will investigate the phenomenon of transovarial interference in the context of its epidemiological significance and the mechanism(s) by which it occurs. Two specific aims are proposed: 1) We will investigate the prevalence and relative efficiency of transovarial interference of R. rickettsii as medicated by other indigenous species of nonpathogenic spotted fever group rickettsiae within D. andersoni and D. variabilis. This will entail field collections of ticks and laboratory evaluation of the interference potential of these agents; and 2) We will initiate studies to examine the molecular mechanism (s) of transovarial interference of R. rickettsii by R. peacockii and other nonpathogenic spotted fever group rickettsiae.

在自然界中，单个扁虱可能会同时感染更多的 而不是一种胞内细菌。有些可能是重要的人类 从感染性血粉或 经卵巢。其他的可能是获得的非致病性共生体 经卵巢。流行性感冒的后果和流行病学意义 扁虱中的多种细菌感染在很大程度上是未知的。我们 提出某些细胞内的相互作用效应 单个扁虱体内的细菌种类可能足够 流行率和大小改变了扁虱的媒介能力。 安氏血吸虫的卵巢含有一种特殊的 斑点热群立克次体非致病种，即 孔雀立克次体，已被证明对随后的共生细菌耐药。 感染其他侵袭性立克次体。因此，卵巢 孔雀立克次体感染安德森假丝酵母菌干扰或 阻断立克次体的正常经卵传播。感染 与两种或两种以上关系密切的立克次体可能会导致 在干扰中(即，一个物种抑制发育和/或 另一方的传播)、互惠(即加强传播 两个物种)，或表型混合(即增加或减少 毒性)。这项提案专门针对经卵巢。 人类病原体立克次体对硬蜱的干扰 经卵巢感染非致病性立克次体的媒介。我们会 在此背景下调查跨卵巢干扰现象 其流行病学意义和发病机制(S) 发生。提出了两个具体目标：1)我们将调查 宫内干扰的患病率和相对效率。 由其他当地非致病性立克次体物种治疗的立克次体 安氏丝虫和变色丝虫中的斑点热群立克次体。 这将需要现场收集扁虱并进行实验室评估。 这些试剂的干扰潜力；以及2)我们将启动 子宫内膜异位症的分子机制研究(S) 孔雀立克次体等非致病性细菌对立克次体的干扰 斑点热群立克次体。