Study of pathology and pathogenesis of leptospirosis in an animal model inoculated with various in vivo passages of leptospires : implications for vaccine development and diagnosis

Abstract

Leptospirosis is a worldwide zoonosis caused by bacteria from the genus leptospira. Several reports have suggested the roles of cytokines in pathogenesis of this infectious disease. In this study, cytokine gene expression in kidneys livers and lung was investigated. In addition to host cytokine gene expression, the expression of leptospira genes at target organs was also studied. Golden Syrian hamsters were injected with virulent or avirulent leptospira interrogans serovar pyrogenes. Kidney liver and lung tissues were collected for pathological examination and gene expression. RNA was extracted from tissues and RT-PCR was performed to demonstrate the expression of hamster HPRT, TNF-Alpha, TGF-Beta, IL-10 and IP-10 in tissues. For leptospira gene expression, 16S rRNA, LipL21, LipL32 and collagenase gene expression was investigated. Our study provided further information on the immune response to leptospira in infected tissues. Although, the difference in pathologies was observed among hamsters infected with avirulent and virulent leptospira, the correlation of cytokine gene expression could not be strongly concluded from the obtained data. LipL21, Lip32 and collagenase expression in kidney, liver and lung was detected which suggested that they may be involved in survival in infected host. Further experiments such as in situ hybridization could demonstrate the roles of both cytokine and leptospira gene expression in pathogenesis in affected organs.