title: Real-Time PCR Reveals Rapid Dissemination of Leptospira interrogans after Intraperitoneal and Conjunctival Inoculation of Hamsters.
abstract: The pathogen Leptospira interrogans is a highly motile spirochete that causes acute and fulminant infections in humans and other accidental hosts. Hematogenous dissemination is important for infection by the pathogen but remains poorly understood because few animal model studies have used sensitive tools to quantify the bacteria. We evaluated the kinetics of leptospiral infection in Golden Syrian hamsters by a sensitive quantitative real-time PCR (TaqMan) with lipl32 as the target gene. The dissemination and bacterial burden were measured after intraperitoneal infection with a high dose (10(8)) or low dose (2.5 × 10(2)) of leptospires. We also examined the conjunctival challenge route to mimic the natural history of infection. Quantification of leptospires in perfused animals revealed that pathogens were detected in all organs of intraperitoneally infected hamsters, including the eye and brain, within 1 h after inoculation of 10(8) virulent L. interrogans bacteria. Peaks of 10(5) to 10(8) leptospires per gram or per milliliter were achieved in blood and all tissues between day 4 and day 8 after intraperitoneal inoculation of high- and low-dose challenges, respectively, coinciding with macroscopic and histological changes. The conjunctival route resulted in a delay in the time to peak organ burden in comparison to intraperitoneal infection, indicating that although infection could be established, penetration efficiency was low across this epithelial barrier. Surprisingly, infection with a large inoculum of high-passage-number attenuated L. interrogans strains resulted in dissemination to all organs in the first 4 days postinfection, albeit with a lower burden, followed by clearance from the blood and organs 7 days postinfection and survival of all animals. These results demonstrate that leptospiral dissemination and tissue invasion occur. In contrast, development of a critical level of tissue burden and pathology are dependent on the virulence of the infecting strain.
authors.affiliation: Epidemiology of Microbial Disease Division, Yale School of Public Health, New Haven, Connecticut, USA elsio.wunder@yale.edu.|Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil.
authors.forename: Elsio A
authors.initials: EA
authors.lastname: Wunder
authors.affiliation: Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil.
authors.forename: Claudio P
authors.initials: CP
authors.lastname: Figueira
authors.affiliation: Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil.
authors.forename: Gisele R
authors.initials: GR
authors.lastname: Santos
authors.affiliation: Institut Pasteur, Unité de Biologie des Spirochètes, Paris, France.|Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, USA.
authors.forename: Kristel
authors.initials: K
authors.lastname: Lourdault
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of California San Diego School of Medicine, La Jolla, California, USA.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Matthias
authors.affiliation: Division of Infectious Diseases, Department of Medicine, University of California San Diego School of Medicine, La Jolla, California, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Vinetz
authors.affiliation: Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ramos
authors.affiliation: Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Haake
authors.affiliation: Institut Pasteur, Unité de Biologie des Spirochètes, Paris, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Picardeau
authors.affiliation: Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil.
authors.forename: Mitermayer G
authors.initials: MG
authors.lastname: Dos Reis
authors.affiliation: Epidemiology of Microbial Disease Division, Yale School of Public Health, New Haven, Connecticut, USA.|Gonçalo Moniz Research Center, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil.
authors.forename: Albert I
authors.initials: AI
authors.lastname: Ko
mesh_terms: D000818:Animals; D058491:Bacterial Load; D003228:Conjunctiva / Q000382:microbiology; D006224:Cricetinae; D004195:Disease Models, Animal; D007921:Leptospira interrogans / Q000502:physiology*; D007922:Leptospirosis / Q000175:diagnosis / Q000382:microbiology* / Q000401:mortality; D008297:Male; D010529:Peritoneal Cavity / Q000382:microbiology; D060888:Real-Time Polymerase Chain Reaction