Lourdault Kristel, Aviat Florence, Picardeau Mathieu
Institut Pasteur, Unité de Biologie des Spirochètes, Paris, France.
J Med Microbiol. 2009 May;58(Pt 5):648-655. doi: 10.1099/jmm.0.008169-0.
The dynamics of leptospirosis infection have been poorly studied. The purpose of this study was to determine the LD(50), rate of bacterial dissemination, histopathology and antibody responses against leptospira following inoculation with the highly virulent Leptospira interrogans Fiocruz L1-130 strain in a guinea pig model of leptospirosis. Three routes of infection (intraperitoneal, conjunctival and subcutaneous inoculation) were used to establish disease in guinea pigs. The size and kinetics of leptospiral burdens in the blood and tissues of infected animals were determined over a 1 week course of infection using quantitative real-time PCR (qPCR). Bacteraemia peaked at day 5 post-infection reaching more than 5x10(4) leptospires ml(-1). The highest spirochaetal load was found in the liver and kidneys, and was associated with alterations in organ tissues and a decline in liver and kidney functions. In contrast, lesions and bacteria were not detected in guinea pigs infected with an avirulent strain derived from a high-passage-number in vitro-passaged variant of the Fiocruz L1-130 strain. The use of qPCR supports the findings of earlier studies and provides an easy and reliable method for the quantification of L. interrogans in the tissues of infected animals. qPCR will be used in future studies to evaluate the efficacy of vaccine candidates against leptospirosis and the virulence of selected L. interrogans mutants relative to the parental strain.
钩端螺旋体病感染的动态过程尚未得到充分研究。本研究的目的是在钩端螺旋体病豚鼠模型中，接种高毒力问号钩端螺旋体Fiocruz L1-130菌株后，确定半数致死剂量（LD50）、细菌传播速率、组织病理学以及针对钩端螺旋体的抗体反应。采用三种感染途径（腹腔内、结膜和皮下接种）在豚鼠中引发疾病。在感染的1周病程中，使用定量实时PCR（qPCR）测定感染动物血液和组织中钩端螺旋体载量的大小和动力学。菌血症在感染后第5天达到峰值，每毫升血液中钩端螺旋体数量超过5×10⁴ 。在肝脏和肾脏中发现了最高的螺旋体载量，并且与器官组织的改变以及肝脏和肾脏功能的下降有关。相比之下，在感染源自Fiocruz L1-130菌株高传代体外传代变体的无毒力菌株的豚鼠中，未检测到病变和细菌。qPCR的应用支持了早期研究的结果，并为定量感染动物组织中的问号钩端螺旋体提供了一种简便可靠的方法。qPCR将用于未来的研究，以评估候选疫苗对钩端螺旋体病的疗效以及所选问号钩端螺旋体突变体相对于亲本菌株的毒力。
