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Shetty A, Kundu S, Vernel-Pauillac F, Ratet G, Werts C, Gomes-Solecki M. Transient Presence of Live Leptospira interrogans in Murine Testes. Microbiol Spectr 2022; 10:e0277521. [PMID: 35446113 PMCID: PMC9241917 DOI: 10.1128/spectrum.02775-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 03/25/2022] [Indexed: 01/01/2023] Open
Abstract
Analysis of Leptospira dissemination and colonization of sex organs in rodents is of significant value as it queries the possibility of mammal-to-mammal venereal transmission. The aim of our study was to evaluate the presence and viability of Leptospira interrogans in testes of mice using models of infection that we previously developed. Using sublethal and lethal doses of bioluminescent strains of L. interrogans serovars Manilae and Copenhageni, we visualized the presence of leptospires in testes of C57BL/6 mice as early as 30 min and up to days 3-4 postinfection. This was confirmed by qPCR for the Copenhageni serovar after lethal infection of C3H/HeJ mice. In this model, no histopathological changes were noticed in testis. We further studied persistence of serovar Copenhageni in C3H/HeJ testes after lethal and sublethal infection, with different doses of leptospires. No viable leptospires were recovered from testes of lethally infected mice. However, we found live culturable Leptospira in testes of 19/19 (100%) sublethally infected mice at the acute phase but not at 15 days postinfection, which corresponds to the chronic phase of renal colonization. The data suggest that colonization of testes with live and potentially infectious leptospires is transient and limited to the spirochetemic phase of infection. Further studies are necessary to evaluate if presence of Leptospira in testes of mice leads to excretion in semen and to venereal transmission to female mice. IMPORTANCE Analysis of venereal transmission of Leptospira is important to determine if direct animal to animal transmission occurs, which could impact measures to prevent and treat leptospirosis. The goal of this study was to determine if live Leptospira colonize mouse testes. We found that colonization of mouse testes with live Leptospira was transient and limited to the acute spirochetemic phase of infection and that transient colonization of the testes was insufficient to cause histopathological changes.
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Affiliation(s)
- Advait Shetty
- Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Suman Kundu
- Department of Microbiology, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Frédérique Vernel-Pauillac
- Institut Pasteur, Université de Paris, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la paroi bactérienne, Paris, France
| | - Gwendoline Ratet
- Institut Pasteur, Université de Paris, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la paroi bactérienne, Paris, France
| | - Catherine Werts
- Institut Pasteur, Université de Paris, CNRS UMR6047, INSERM U1306, Unité de Biologie et Génétique de la paroi bactérienne, Paris, France
| | - Maria Gomes-Solecki
- Department of Pharmaceutical Sciences, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
- Department of Microbiology, Immunology and Biochemistry, The University of Tennessee Health Science Center, Memphis, Tennessee, USA
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Anti-Leptospira immunoglobulin profiling in mice reveals strain specific IgG and persistent IgM responses associated with virulence and renal colonization. PLoS Negl Trop Dis 2021; 15:e0008970. [PMID: 33705392 PMCID: PMC8007020 DOI: 10.1371/journal.pntd.0008970] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 03/29/2021] [Accepted: 02/23/2021] [Indexed: 12/14/2022] Open
Abstract
Leptospira interrogans is a pathogenic spirochete responsible for leptospirosis, a neglected, zoonotic reemerging disease. Humans are sensitive hosts and may develop severe disease. Some animal species, such as rats and mice can become asymptomatic renal carriers. More than 350 leptospiral serovars have been identified, classified on the basis of the antibody response directed against the lipopolysaccharide (LPS). Similarly to whole inactivated bacteria used as human vaccines, this response is believed to confer only short-term, serogroup-specific protection. The immune response of hosts against leptospires has not been thoroughly studied, which complicates the testing of vaccine candidates. In this work, we studied the immunoglobulin (Ig) profiles in mice infected with L. interrogans over time to determine whether this humoral response confers long-term protection after homologous challenge six months post-infection. Groups of mice were injected intraperitoneally with 2×107 leptospires of one of three pathogenic serovars (Manilae, Copenhageni or Icterohaemorrhagiae), attenuated mutants or heat-killed bacteria. Leptospira-specific immunoglobulin (IgA, IgM, IgG and 4 subclasses) produced in the first weeks up to 6 months post-infection were measured by ELISA. Strikingly, we found sustained high levels of IgM in mice infected with the pathogenic Manilae and Copenhageni strains, both colonizing the kidney. In contrast, the Icterohaemorrhagiae strain did not lead to kidney colonization, even at high dose, and triggered a classical IgM response that peaked at day 8 post-infection and disappeared. The virulent Manilae and Copenhageni serovars elicited high levels and similar profiles of IgG subclasses in contrast to Icterohaemorrhagiae strains that stimulated weaker antibody responses. Inactivated heat-killed Manilae strains elicited very low responses. However, all mice pre-injected with leptospires challenged with high doses of homologous bacteria did not develop acute leptospirosis, and all antibody responses were boosted after challenge. Furthermore, we showed that 2 months post-challenge, mice pre-infected with the attenuated M895 Manilae LPS mutant or heat-killed bacterin were completely protected against renal colonization. In conclusion, we observed a sustained IgM response potentially associated with chronic leptospiral renal infection. We also demonstrated in mice different profiles of protective and cross-reactive antibodies after L. interrogans infection, depending on the serovar and virulence of strains. Leptospira interrogans is a pathogenic spirochete responsible for leptospirosis, a neglected zoonotic reemerging disease. The immune response of hosts against these bacteria has not been thoroughly studied. Here, we studied over 6 months the antibody profiles in mice infected with L. interrogans and determined whether this humoral response confers long-term protection after homologous challenge six months after primary infection. Groups of mice were infected intraperitoneally with 2×107 bacteria of one of three different pathogenic serovars (Manilae, Copenhageni and Icterohaemorrhagiae) and some corresponding attenuated avirulent mutants. We measured by ELISA each type of Leptospira-specific immunoglobulin (Ig) (IgA, IgM, IgG and 4 subclasses) produced in the first weeks up to 6 months post-infection and studied their cross-reactivities among serovars. We showed different profiles of antibody response after L. interrogans challenge in mice, depending on the serovar and virulence of strains. However, all infected mice, including the ones harboring low antibody levels, like mice vaccinated with an inactivated, heat-killed strain, were protected against leptospirosis after challenge. Notably, we also showed an unusual sustained IgM response associated with chronic leptospiral colonization. Altogether, this long-term immune protection is different from what is known in humans and warrants further investigation.
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Holzapfel M, Bonhomme D, Cagliero J, Vernel-Pauillac F, Fanton d’Andon M, Bortolussi S, Fiette L, Goarant C, Wunder EA, Picardeau M, Ko AI, Werling D, Matsui M, Boneca IG, Werts C. Escape of TLR5 Recognition by Leptospira spp.: A Rationale for Atypical Endoflagella. Front Immunol 2020; 11:2007. [PMID: 32849665 PMCID: PMC7431986 DOI: 10.3389/fimmu.2020.02007] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/24/2020] [Indexed: 12/26/2022] Open
Abstract
Leptospira (L.) interrogans are invasive bacteria responsible for leptospirosis, a worldwide zoonosis. They possess two periplasmic endoflagellae that allow their motility. L. interrogans are stealth pathogens that escape the innate immune recognition of the NOD-like receptors NOD1/2, and the human Toll-like receptor (TLR)4, which senses peptidoglycan and lipopolysaccharide (LPS), respectively. TLR5 is another receptor of bacterial cell wall components, recognizing flagellin subunits. To study the contribution of TLR5 in the host defense against leptospires, we infected WT and TLR5 deficient mice with pathogenic L. interrogans and tracked the infection by in vivo live imaging of bioluminescent bacteria or by qPCR. We did not identify any protective or inflammatory role of murine TLR5 for controlling pathogenic Leptospira. Likewise, subsequent in vitro experiments showed that infections with different live strains of L. interrogans and L. biflexa did not trigger TLR5 signaling. However, unexpectedly, heat-killed bacteria stimulated human and bovine TLR5, but did not, or barely induced stimulation via murine TLR5. Abolition of TLR5 recognition required extensive boiling time of the bacteria or proteinase K treatment, showing an unusual high stability of the leptospiral flagellins. Interestingly, after using antimicrobial peptides to destabilize live leptospires, we detected TLR5 activity, suggesting that TLR5 could participate in the fight against leptospires in humans or cattle. Using different Leptospira strains with mutations in the flagellin proteins, we further showed that neither FlaA nor Fcp participated in the recognition by TLR5, suggesting a role for the FlaB. FlaB have structural homology to Salmonella FliC, and possess conserved residues important for TLR5 activation, as shown by in silico analyses. Accordingly, we found that leptospires regulate the expression of FlaB mRNA according to the growth phase in vitro, and that infection with L. interrogans in hamsters and in mice downregulated the expression of the FlaB, but not the FlaA subunits. Altogether, in contrast to different bacteria that modify their flagellin sequences to escape TLR5 recognition, our study suggests that the peculiar central localization and stability of the FlaB monomers in the periplasmic endoflagellae, associated with the downregulation of FlaB subunits in hosts, constitute an efficient strategy of leptospires to escape the TLR5 recognition and the induced immune response.
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Affiliation(s)
- Marion Holzapfel
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- CNRS, UMR 2001 Microbiologie Intégrative et Moléculaire, Paris, France
- Institut National de la Santé et de la Recherche Médicale, Equipe Avenir, Paris, France
| | - Delphine Bonhomme
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- CNRS, UMR 2001 Microbiologie Intégrative et Moléculaire, Paris, France
- Institut National de la Santé et de la Recherche Médicale, Equipe Avenir, Paris, France
- Sorbonne Paris Cité, Université de Paris, Paris, France
| | - Julie Cagliero
- Institut Pasteur de Nouvelle Calédonie, Immunity and Inflammation Group, Institut Pasteur International Network, Noumea, France
| | - Frédérique Vernel-Pauillac
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- CNRS, UMR 2001 Microbiologie Intégrative et Moléculaire, Paris, France
- Institut National de la Santé et de la Recherche Médicale, Equipe Avenir, Paris, France
| | - Martine Fanton d’Andon
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- CNRS, UMR 2001 Microbiologie Intégrative et Moléculaire, Paris, France
- Institut National de la Santé et de la Recherche Médicale, Equipe Avenir, Paris, France
| | - Sophia Bortolussi
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- CNRS, UMR 2001 Microbiologie Intégrative et Moléculaire, Paris, France
- Institut National de la Santé et de la Recherche Médicale, Equipe Avenir, Paris, France
| | - Laurence Fiette
- Unité Histopathologie Humaine et Modèles Animaux, Institut Pasteur, Paris, France
| | - Cyrille Goarant
- Leptospirosis Research and Expertise Unit, Institut Pasteur International Network, Institut Pasteur de Nouvelle Calédonie, Noumea, France
| | - Elsio A. Wunder
- Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States
| | | | - Albert I. Ko
- Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Brazilian Ministry of Health, Salvador, Brazil
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States
| | - Dirk Werling
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | - Mariko Matsui
- Institut Pasteur de Nouvelle Calédonie, Immunity and Inflammation Group, Institut Pasteur International Network, Noumea, France
| | - Ivo G. Boneca
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- CNRS, UMR 2001 Microbiologie Intégrative et Moléculaire, Paris, France
- Institut National de la Santé et de la Recherche Médicale, Equipe Avenir, Paris, France
| | - Catherine Werts
- Institut Pasteur, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France
- CNRS, UMR 2001 Microbiologie Intégrative et Moléculaire, Paris, France
- Institut National de la Santé et de la Recherche Médicale, Equipe Avenir, Paris, France
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