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Lv T, Xie X, Diao L, Jiang S, Ding Y, Yuan X, Gong L, Chen X, Zhang W, Cao Y. Leptospira-specific immunoglobulin Y (IgY) is protective in infected hamsters. Vaccine 2024; 42:3220-3229. [PMID: 38641497 DOI: 10.1016/j.vaccine.2024.04.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/21/2024]
Abstract
Leptospirosis, a globally significant zoonotic disease caused by pathogenic Leptospira, continues to threaten the health and public safety of both humans and animals. Current clinical treatment of leptospirosis mainly relies on antibiotics but their efficacy in severe cases is controversial. Passive immunization has a protective effect in the treatment of infectious diseases. In addition, chicken egg yolk antibody (IgY) has gained increasing attention as a safe passive immunization agent. This study aimed to investigate whether hens produce specific IgY after immunization with inactivated Leptospira and the protective effect of specific IgY against leptospirosis. First, it was demonstrated that specific IgY could be extracted from the eggs of hens vaccinated with inactivated Leptospira and that specific IgY can specifically recognize and bind homotypic Leptospira with a high titre, as shown by MAT and ELISA. Next, we tested the therapeutic effects of IgY in early and late leptospirosis using a hamster model. The results showed that early specific IgY treatment increased the survival rate of hamsters to 100%, alleviated pathological damage to the liver, kidney, and lung, reduced leptospiral burden, and restored haematological indices as well as functional indicators of the liver and kidney. The therapeutic effect of early specific IgY was comparable to that of doxycycline. Late IgY treatment also enhanced the survival rate of hamsters and improved the symptoms of leptospirosis similar to early IgY treatment. However, the therapeutic effect of late IgY treatment was better when combined with doxycycline. Furthermore, no Leptospira colonization was observed in the kidneys, livers, or lungs of the surviving hamsters treated with specific IgY. Mechanistically, IgY was found to inhibit the growth and adhesion to cells of Leptospira. In conclusion, passive immunotherapy with specific IgY can be considered an effective treatment for leptospirosis, and may replace antibiotics regarding its therapeutic effects.
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Affiliation(s)
- Tianbao Lv
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xufeng Xie
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Luteng Diao
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Shuang Jiang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Yue Ding
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xin Yuan
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Lingling Gong
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xi Chen
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Wenlong Zhang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China; State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China.
| | - Yongguo Cao
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Jilin University, Changchun 130062, China; State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China.
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Bunde TT, de Oliveira NR, Santos FDS, Pedra ACK, Maia MAC, Dellagostin OA, Oliveira Bohn TL. Characterization of cellular immune response in hamsters immunized with recombinant vaccines against leptospirosis based on LipL32:LemA:LigAni chimeric protein. Microb Pathog 2023; 184:106378. [PMID: 37802158 DOI: 10.1016/j.micpath.2023.106378] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/29/2023] [Accepted: 10/02/2023] [Indexed: 10/08/2023]
Abstract
In the last 20 years, various research groups have endeavored to develop recombinant vaccines against leptospirosis to overcome the limitations of commercially available bacterins. Numerous antigens and vaccine formulations have been tested thus far. However, the analysis of cellular response in these vaccine formulations is not commonly conducted, primarily due to the scarcity of supplies and kits for the hamster animal model. Our research group has already tested the Q1 antigen, a chimeric protein combining the immunogenic regions of LipL32, LemA, and LigANI, in recombinant subunit and BCG-vectored vaccines. In both strategies, 100 % of the hamsters were protected against clinical signs of leptospirosis. However, only the recombinant BCG-vectored vaccine provided protection against renal colonization. Thus, the objective of this study is to characterize the cellular immune response in hamsters immunized with different vaccine formulations based on the Q1 antigen through transcriptional analysis of cytokines. The hamsters were allocated into groups and vaccinated as follows: recombinant subunit (rQ1), recombinant BCG (rBCG:Q1), and saline and BCG Pasteur control vaccines. To assess the cellular response induced by the vaccines, we cultured and stimulated splenocytes, followed by RNA extraction from the cells and analysis of cytokines using real-time PCR. The results revealed that the recombinant subunit vaccine elicited a Th2-type response, characterized by the expression of cytokines IL-10, IL-1α, and TNF-α. This pattern closely resembles the cytokines expressed in severe cases of leptospirosis. On the other hand, the rBCG-vectored vaccine induced a Th1-type response with significant up-regulation of IFN-γ. These findings suggest the involvement of the cellular response and the IFN-γ mediated inflammatory response in the sterilizing immunity mediated by rBCG. Therefore, this study may assist future investigations in characterizing the cellular response in hamsters, aiming to elucidate the mechanisms of efficacy and establish potential correlates of protection.
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Affiliation(s)
- Tiffany Thurow Bunde
- Laboratório de Vacinologia, Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil
| | - Natasha Rodrigues de Oliveira
- Laboratório de Vacinologia, Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil
| | - Francisco Denis Souza Santos
- Laboratório de Vacinologia, Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil
| | - Ana Carolina Kurz Pedra
- Laboratório de Vacinologia, Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil
| | - Mara Andrade Colares Maia
- Laboratório de Vacinologia, Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil
| | - Odir Antônio Dellagostin
- Laboratório de Vacinologia, Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil
| | - Thaís Larré Oliveira Bohn
- Laboratório de Vacinologia, Centro de Desenvolvimento Tecnológico, Núcleo de Biotecnologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil.
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de Oliveira NR, Santos FDS, Dos Santos VAC, Maia MAC, Oliveira TL, Dellagostin OA. Challenges and Strategies for Developing Recombinant Vaccines against Leptospirosis: Role of Expression Platforms and Adjuvants in Achieving Protective Efficacy. Pathogens 2023; 12:787. [PMID: 37375478 DOI: 10.3390/pathogens12060787] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/29/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
The first leptospiral recombinant vaccine was developed in the late 1990s. Since then, progress in the fields of reverse vaccinology (RV) and structural vaccinology (SV) has significantly improved the identification of novel surface-exposed and conserved vaccine targets. However, developing recombinant vaccines for leptospirosis faces various challenges, including selecting the ideal expression platform or delivery system, assessing immunogenicity, selecting adjuvants, establishing vaccine formulation, demonstrating protective efficacy against lethal disease in homologous challenge, achieving full renal clearance using experimental models, and reproducibility of protective efficacy against heterologous challenge. In this review, we highlight the role of the expression/delivery system employed in studies based on the well-known LipL32 and leptospiral immunoglobulin-like (Lig) proteins, as well as the choice of adjuvants, as key factors to achieving the best vaccine performance in terms of protective efficacy against lethal infection and induction of sterile immunity.
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Affiliation(s)
- Natasha Rodrigues de Oliveira
- Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas 96010-610, RS, Brazil
| | - Francisco Denis Souza Santos
- Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas 96010-610, RS, Brazil
| | | | - Mara Andrade Colares Maia
- Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas 96010-610, RS, Brazil
| | - Thaís Larré Oliveira
- Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas 96010-610, RS, Brazil
| | - Odir Antônio Dellagostin
- Núcleo de Biotecnologia, Centro de Desenvolvimento Tecnológico, Universidade Federal de Pelotas, Pelotas 96010-610, RS, Brazil
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Analysis of LruC lipoprotein and identification of peptides candidates for vaccine development and diagnosis of leptospirosis. PLoS One 2023; 18:e0281344. [PMID: 36745643 PMCID: PMC9901810 DOI: 10.1371/journal.pone.0281344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 01/20/2023] [Indexed: 02/07/2023] Open
Abstract
Leptospirosis is a public health concern with lethality around 15% of the total cases. The current vaccines against Leptospira infection based on bacterins have several limitations, which require urgent development of new ones. In this context, groundbreaking approaches such as peptide-vaccines could be used to come around with promising results. Our goal was to identify conserved and immunogenic epitopes from the lipoprotein LruC that could interact with Major Histocompatibility Complex (MHC) I and II. LruC is a conserved lipoprotein expressed during leptospirosis that is considered among vaccine candidates and can be used as source for development of peptide-based vaccines. We searched for peptides that would be recognized by antibodies from either serum of hamsters previously immunized with low-LPS bacterin vaccines or from serum of patients diagnosed with leptospirosis. Immuno properties of seven peptides from LruC protein were evaluated in silico and by Dot Blot assay, and validate by ELISA. Preliminary results pointed one promising peptide that was recognized by the sera. In conclusion, the immunoinformatic approach helps the search and screening of peptides, while the Dot Blot assay, a simple and effective tool, helps to test and validate them. Thus, these prospective techniques together were validated to identify and validate potential peptides for further investigation as peptide-based vaccines or diagnostic methods.
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Maia MAC, Bettin EB, Barbosa LN, de Oliveira NR, Bunde TT, Pedra ACK, Rosa GA, da Rosa EEB, Seixas Neto ACP, Grassmann AA, McFadden J, Dellagostin OA, McBride AJA. Challenges for the development of a universal vaccine against leptospirosis revealed by the evaluation of 22 vaccine candidates. Front Cell Infect Microbiol 2022; 12:940966. [PMID: 36275031 PMCID: PMC9586249 DOI: 10.3389/fcimb.2022.940966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
Leptospirosis is a neglected disease of man and animals that affects nearly half a million people annually and causes considerable economic losses. Current human vaccines are inactivated whole-cell preparations (bacterins) of Leptospira spp. that provide strong homologous protection yet fail to induce a cross-protective immune response. Yearly boosters are required, and serious side-effects are frequently reported so the vaccine is licensed for use in humans in only a handful of countries. Novel universal vaccines require identification of conserved surface-exposed epitopes of leptospiral antigens. Outer membrane β-barrel proteins (βb-OMPs) meet these requirements and have been successfully used as vaccines for other diseases. We report the evaluation of 22 constructs containing protein fragments from 33 leptospiral βb-OMPs, previously identified by reverse and structural vaccinology and cell-surface immunoprecipitation. Three-dimensional structures for each leptospiral βb-OMP were predicted by I-TASSER. The surface-exposed epitopes were predicted using NetMHCII 2.2 and BepiPred 2.0. Recombinant constructs containing regions from one or more βb-OMPs were cloned and expressed in Escherichia coli. IMAC-purified recombinant proteins were adsorbed to an aluminium hydroxide adjuvant to produce the vaccine formulations. Hamsters (4-6 weeks old) were vaccinated with 2 doses containing 50 – 125 μg of recombinant protein, with a 14-day interval between doses. Immunoprotection was evaluated in the hamster model of leptospirosis against a homologous challenge (10 – 20× ED50) with L. interrogans serogroup Icterohaemorrhagiae serovar Copenhageni strain Fiocruz L1-130. Of the vaccine formulations, 20/22 were immunogenic and induced significant humoral immune responses (IgG) prior to challenge. Four constructs induced significant protection (100%, P < 0.001) and sterilizing immunity in two independent experiments, however, this was not reproducible in subsequent evaluations (0 – 33.3% protection, P > 0.05). The lack of reproducibility seen in these challenge experiments and in other reports in the literature, together with the lack of immune correlates and commercially available reagents to characterize the immune response, suggest that the hamster may not be the ideal model for evaluation of leptospirosis vaccines and highlight the need for evaluation of alternative models, such as the mouse.
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Affiliation(s)
- Mara A. C. Maia
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Everton B. Bettin
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Liana N. Barbosa
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Natasha R. de Oliveira
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Tiffany T. Bunde
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Ana Carolina K. Pedra
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Guilherme A. Rosa
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Elias E. B. da Rosa
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Amilton C. P. Seixas Neto
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - André A. Grassmann
- Department of Medicine, University of Connecticut Health, Farmington, CT, United States
| | - Johnjoe McFadden
- School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Odir A. Dellagostin
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
| | - Alan J. A. McBride
- Biotechnology Unit, Technological Development Centre, Federal University of Pelotas, Pelotas, Rio Grande do Sul, Brazil
- School of Biosciences and Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
- *Correspondence: Alan J. A. McBride,
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Chaurasia R, Salovey A, Guo X, Desir G, Vinetz JM. Vaccination With Leptospira interrogans PF07598 Gene Family-Encoded Virulence Modifying Proteins Protects Mice From Severe Leptospirosis and Reduces Bacterial Load in the Liver and Kidney. Front Cell Infect Microbiol 2022; 12:926994. [PMID: 35837473 PMCID: PMC9274288 DOI: 10.3389/fcimb.2022.926994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 05/24/2022] [Indexed: 12/29/2022] Open
Abstract
The molecular and cellular pathogenesis of leptospirosis remains poorly understood. Based on comparative bacterial genomics data, we recently identified the hypothetical PF07598 gene family as encoding secreted exotoxins (VM proteins) that mediate cytotoxicity in vitro. To address whether VM proteins mediate in vivo leptospirosis pathogenesis, we tested the hypothesis that VM protein immunization of mice would protect against lethal challenge infection and reduce bacterial load in key target organs. C3H/HeJ mice were immunized with recombinant E. coli-produced, endotoxin-free, leptospiral VM proteins (derived from L. interrogans serovar Lai) in combination with the human-compatible adjuvant, glucopyranoside lipid A/squalene oil-in-water. Mice receiving full length recombinant VM proteins were protected from lethal challenge infection by L. interrogans serovar Canicola and had a 3-4 log10 reduction in bacterial load in the liver and kidney. These experiments show that immunization with recombinant VM proteins prevents leptospirosis clinical pathogenesis and leads to markedly reduced key target organ infection in this animal model. These data support the role of leptospiral VM proteins as virulence factors and suggest the possibility that a VM protein-based, serovar-independent, pan-leptospirosis vaccine may be feasible.
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Affiliation(s)
- Reetika Chaurasia
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Aryeh Salovey
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Xiaojia Guo
- Section of Nephrology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Gary Desir
- Section of Nephrology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
| | - Joseph M. Vinetz
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, United States
- *Correspondence: Joseph M. Vinetz,
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Techawiwattanaboon T, Courant T, Brunner L, Sathean-anan-kun S, Krangvichian P, Iadsee N, Nakornpakdee Y, Sangjun N, Komanee P, Collin N, Ruxrungtham K, Patarakul K. Designing Adjuvant Formulations to Promote Immunogenicity and Protective Efficacy of Leptospira Immunoglobulin-Like Protein A Subunit Vaccine. Front Cell Infect Microbiol 2022; 12:918629. [PMID: 35782116 PMCID: PMC9243587 DOI: 10.3389/fcimb.2022.918629] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 05/17/2022] [Indexed: 11/23/2022] Open
Abstract
The leptospirosis burden on humans, especially in high-risk occupational groups and livestock, leads to public health and economic problems. Leptospirosis subunit vaccines have been under development and require further improvement to provide complete protection. Adjuvants can be used to enhance the amplitude, quality, and durability of immune responses. Previously, we demonstrated that LMQ adjuvant (neutral liposomes containing monophosphoryl lipid A (MPL) and Quillaja saponaria derived QS21 saponin) promoted protective efficacy of LigAc vaccine against Leptospira challenge. To promote immunogenicity and protective efficacy of the subunit vaccines, three alternative adjuvants based on neutral liposomes or squalene-in-water emulsion were evaluated in this study. LQ and LQuil adjuvants combined the neutral liposomes with the QS21 saponin or Quillaja saponaria derived QuilA® saponin, respectively. SQuil adjuvant combined a squalene-in-water emulsion with the QuilA® saponin. The immunogenicity and protective efficacy of LigAc (20 µg) formulated with the candidate adjuvants were conducted in golden Syrian hamsters. Hamsters were vaccinated three times at a 2-week interval, followed by a homologous challenge of L. interrogans serovar Pomona. The results showed that LigAc combined with LQ, LQuil, or SQuil adjuvants conferred substantial antibody responses and protective efficacy (survival rate, pathological change, and Leptospira renal colonization) comparable to LMQ adjuvant. The LigAc+LQ formulation conferred 62.5% survival but was not significantly different from LigAc+LMQ, LigAc+LQuil, and LigAc+SQuil formulations (50% survival). This study highlights the potential of saponin-containing adjuvants LMQ, LQ, LQuil, and SQuil for both human and animal leptospirosis vaccines.
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Affiliation(s)
- Teerasit Techawiwattanaboon
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
| | - Thomas Courant
- Vaccine Formulation Institute, Plan-Les-Ouates, Switzerland
| | - Livia Brunner
- Vaccine Formulation Institute, Plan-Les-Ouates, Switzerland
| | - Suwitra Sathean-anan-kun
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
| | - Pratomporn Krangvichian
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
- Medical Microbiology, Interdisciplinary Program, Graduate School, Chulalongkorn University, Bangkok, Thailand
| | - Nutta Iadsee
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
- Medical Microbiology, Interdisciplinary Program, Graduate School, Chulalongkorn University, Bangkok, Thailand
| | - Yaowarin Nakornpakdee
- Department of Pathobiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Noppadon Sangjun
- Laboratory Animal Section, Analysis Division, Armed Force Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
| | - Pat Komanee
- Laboratory Animal Section, Analysis Division, Armed Force Research Institute of Medical Sciences (AFRIMS), Bangkok, Thailand
| | - Nicolas Collin
- Vaccine Formulation Institute, Plan-Les-Ouates, Switzerland
| | - Kiat Ruxrungtham
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
| | - Kanitha Patarakul
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- Chula Vaccine Research Center (Chula VRC), Center of Excellence in Vaccine Research and Development, Chulalongkorn University, Bangkok, Thailand
- *Correspondence: Kanitha Patarakul, ;
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TonB-dependent receptor epitopes expressed in M. bovis BCG induced significant protection in the hamster model of leptospirosis. Appl Microbiol Biotechnol 2021; 106:173-184. [PMID: 34893930 PMCID: PMC8664668 DOI: 10.1007/s00253-021-11726-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/26/2021] [Accepted: 11/30/2021] [Indexed: 12/02/2022]
Abstract
Abstract
Leptospirosis is an emerging infectious disease caused by pathogenic Leptospira spp. A universal vaccine against leptospirosis is likely to require highly conserved epitopes from pathogenic leptospires that are exposed on the bacterial surface and that generate a protective and sterilizing immune response. Our group recently identified several genes predicted to encode TonB-dependent receptors (TBDR) in Leptospira interrogans using a reverse vaccinology approach. Three leptospiral TBDRs were previously described and partially characterized as ferric-citrate, hemin, and cobalamin transporters. In the current study, we designed a fusion protein composed of predicted surface-exposed epitopes from three conserved leptospiral TBDRs. Based on their three-dimensional structural models and the prediction of immunogenic regions, nine putative surface-exposed fragments were selected to compose a recombinant chimeric protein. A Mycobacterium bovis BCG strain expressing this chimeric antigen encoded in the pUP500/PpAN mycobacterial expression vector was used to immunize Syrian hamsters. All animals (20/20) vaccinated with recombinant BCG survived infection with an endpoint dose of L. interrogans (p < 0.001). No animal survived in the negative control group. Immunization with our recombinant BCG elicited a humoral immune response against leptospiral TBDRs, as demonstrated by ELISA and immunoblot. No leptospiral DNA was detected by lipL32 qPCR in the kidneys of vaccinated hamsters. Similarly, no growth was observed in macerated kidney cultures from the same animals, suggesting the induction of a sterilizing immune response. Design of new vaccine antigens based on the structure of outer membrane proteins is a promising approach to overcome the impact of leptospirosis by vaccination. Key points • Predicted surface-exposed epitopes were identified in three leptospiral TBDRs. • An M. bovis BCG strain expressing a chimeric protein (rTBDRchi) was constructed. • Hamsters vaccinated with rBCG:TBDRchi were protected from lethal leptospirosis. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1007/s00253-021-11726-9.
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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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A Comparison of Intramuscular and Subcutaneous Administration of LigA Subunit Vaccine Adjuvanted with Neutral Liposomal Formulation Containing Monophosphoryl Lipid A and QS21. Vaccines (Basel) 2020; 8:vaccines8030494. [PMID: 32882903 PMCID: PMC7565420 DOI: 10.3390/vaccines8030494] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/28/2020] [Accepted: 08/28/2020] [Indexed: 01/04/2023] Open
Abstract
Leptospirosis vaccines with higher potency and reduced adverse effects are needed for human use. The carboxyl terminal domain of leptospiral immunoglobulin like protein A (LigAc) is currently the most promising candidate antigen for leptospirosis subunit vaccine. However, LigAc-based vaccines were unable to confer sterilizing immunity against Leptospira infection in animal models. Several factors including antigen properties, adjuvant, delivery system, and administration route need optimization to maximize vaccine efficacy. Our previous report demonstrated protective effects of the recombinant LigAc (rLigAc) formulated with liposome-based adjuvant, called LMQ (neutral liposome combined with monophosphoryl lipid A and Quillaja saponaria fraction 21) in hamsters. This study aimed to evaluate the impact of two commonly used administration routes, intramuscular (IM) and subcutaneous (SC), on immunogenicity and protective efficacy of rLigAc-LMQ administrated three times at 2-week interval. Two IM vaccinations triggered significantly higher levels of total anti-rLigAc IgG than two SC injections. However, comparable IgG titers and IgG2/IgG1 ratio was observed for both routes after the third immunization. The route of vaccine administration did not influence the survival rate (60%) and renal colonization against lethal Leptospira challenge. Importantly, the kidneys of IM group showed no pathological lesions while the SC group showed mild damage. In conclusion, IM vaccination with rLigAc-LMQ not only elicited faster antibody production but also protected from kidney damage following leptospiral infection better than SC immunization. However, both tested routes did not influence protective efficacy in terms of survival rate and the level of renal colonization.
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