1
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Expression of Concern: Cell-Associated Flagella Enhance the Protection Conferred by Mucosally-Administered Attenuated Salmonella Paratyphi A Vaccines. PLoS Negl Trop Dis 2024; 18:e0012160. [PMID: 38709719 PMCID: PMC11073665 DOI: 10.1371/journal.pntd.0012160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024] Open
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2
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Hajra D, Nair AV, Chakravortty D. Decoding the invasive nature of a tropical pathogen of concern: The invasive non-Typhoidal Salmonella strains causing host-restricted extraintestinal infections worldwide. Microbiol Res 2023; 277:127488. [PMID: 37716125 DOI: 10.1016/j.micres.2023.127488] [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: 07/28/2023] [Revised: 09/01/2023] [Accepted: 09/06/2023] [Indexed: 09/18/2023]
Abstract
Invasive-Non-Typhoidal Salmonella (iNTS) are the major cause of health concern in the low-income, under-developed nations in Africa and Asia that lack proper sanitation facilities. Around 5% of the NTS cases give rise to invasive, extraintestinal diseases leading to focal infections like osteomyelitis, meningitis, osteoarthritis, endocarditis and neonatal sepsis. iNTS serovars like S. Typhimurium, S. Enteritidis, S. Dublin, S. Choleraesuis show a greater propensity to become invasive than others which hints at the genetic basis of their emergence. The major risk factors attributing to the invasive diseases include immune-compromised individuals having co-infection with malaria or HIV, or suffering from malnutrition. The rampant use of antibiotics leading to the emergence of multi-drug resistant strains poses a great challenge in disease management. An extensive understanding of the iNTS pathogenesis and its epidemiology will open up avenues for the development of new vaccination and therapeutic strategies to restrict the spread of this neglected disease.
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Affiliation(s)
- Dipasree Hajra
- Department of Microbiology & Cell Biology, Indian Institute of Science, India
| | - Abhilash Vijay Nair
- Department of Microbiology & Cell Biology, Indian Institute of Science, India
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3
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Li J, Yang Y, Fan Z, Huang Z, Chen J, Liu Q. Salmonella typhimurium targeting with monoclonal antibodies prevents infection in mice. PLoS Negl Trop Dis 2023; 17:e0011579. [PMID: 38048368 PMCID: PMC10745141 DOI: 10.1371/journal.pntd.0011579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 12/22/2023] [Accepted: 08/08/2023] [Indexed: 12/06/2023] Open
Abstract
Salmonella is a prevalent foodborne and waterborne pathogens threating global public health and food safety. Given the diversity of Salmonella serotypes and the emergence of antibiotic-resistant strains, there is an urgent need for the development of broadly protective therapies. This study aims to prepare monoclonal antibodies (Mabs) with broad reactivity against multi-serotype Salmonella strains, potentially offering cross-protection. We prepared two Mabs F1D4 and B7D4 against protein FliK and BcsZ, two potential vaccine candidates against multi-serotype Salmonella. The two Mabs belonging to IgG1 isotype exhibited high titers of 1:256,000 and 1:512,000 respectively, as well as broad cross-reactivity against 28 different serotypes of Salmonella strains with percentages of 89.29% and 92.86%, correspondingly. Neutralizing effects of the two Mabs on Salmonella growth, adhesion, invasion and motility was evaluated in vitro using bacteriostatic and bactericidal activity with and without complement and bacterial invasion inhibition assay. Additionally, cytotoxicity assays, animal toxicity analyses, and pharmacokinetic evaluations demonstrated the safety and sustained effectiveness of both Mabs. Furthermore, F1D4 or B7D4-therapy in mice challenged with S. Typhimurium LT2 exhibited milder organs damage and lower Salmonella colonization, as well as the higher relative survival of 86.67% and 93.33% respectively. This study produced two broadly reactive and potential cross protective Mabs F1D4 and B7D4, which offered new possibilities for immunotherapy of salmonellosis.
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Affiliation(s)
- Jie Li
- Second Affiliated Hospital, Southern University of Science and Technology, Shenzhen Third People’s Hospital, Shenzhen, China
| | - Yang Yang
- Second Affiliated Hospital, Southern University of Science and Technology, Shenzhen Third People’s Hospital, Shenzhen, China
| | - Zhongyi Fan
- Second Affiliated Hospital, Southern University of Science and Technology, Shenzhen Third People’s Hospital, Shenzhen, China
| | - Zhiqiang Huang
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, PR China
| | - Jun Chen
- Second Affiliated Hospital, Southern University of Science and Technology, Shenzhen Third People’s Hospital, Shenzhen, China
| | - Qing Liu
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology, Shanghai, PR China
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Xie L, Ming L, Ding M, Deng L, Liu M, Cong Y. Paratyphoid Fever A: Infection and Prevention. Front Microbiol 2022; 13:945235. [PMID: 35875577 PMCID: PMC9304857 DOI: 10.3389/fmicb.2022.945235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/15/2022] [Indexed: 11/17/2022] Open
Abstract
Enteric fever is caused by Salmonella enterica serovar Typhi, Salmonella enterica serovar Paratyphi A, B, and C. While S. Typhi remains the primary causative agent of enteric fever, S. Paratyphi A is responsible for an increasing portion of enteric fever incidence. However, the current available vaccines for enteric fever are all developed from S. Typhi, and lack adequate cross immune protection against paratyphoid fever A. Therefore, paratyphoid A vaccines are urgently needed. The present paper reviews the latest progresses in pathogenesis, global burden, infection features of paratyphoid fever A, as well as the status of vaccine development, highlighting the necessity for the development of vaccines against paratyphoid fever A.
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Affiliation(s)
- Lei Xie
- Precision Medicine Center, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
| | - Lan Ming
- Department of Clinical Laboratory, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
| | - Manlin Ding
- Precision Medicine Center, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
- Department of Clinical Laboratory, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
| | - Luxin Deng
- Department of Clinical Laboratory, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Miao Liu
- Precision Medicine Center, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
| | - Yanguang Cong
- Precision Medicine Center, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
- Department of Clinical Laboratory, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
- *Correspondence: Yanguang Cong,
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iTRAQ-based quantitative proteome analysis insights into cold stress of Winter Rapeseed (Brassica rapa L.) grown in the field. Sci Rep 2021; 11:23434. [PMID: 34873178 PMCID: PMC8648733 DOI: 10.1038/s41598-021-02707-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/17/2021] [Indexed: 12/02/2022] Open
Abstract
Winter rapeseed (Brassica rapa L.) is a major oilseed crop in Northern China, where its production was severely affected by chilling and freezing stress. However, not much is known about the role of differentially accumulated proteins (DAPs) during the chilling and freezing stress. In this study, isobaric tag for relative and absolute quantification (iTRAQ) technology was performed to identify DAPs under freezing stress. To explore the molecular mechanisms of cold stress tolerance at the cellular and protein levels, the morphological and physiological differences in the shoot apical meristem (SAM) of two winter rapeseed varieties, Longyou 7 (cold-tolerant) and Lenox (cold-sensitive), were explored in field-grown plants. Compared to Lenox, Longyou 7 had a lower SAM height and higher collar diameter. The level of malondialdehyde (MDA) and indole-3-acetic acid (IAA) content was also decreased. Simultaneously, the soluble sugars (SS) content, superoxide dismutase (SOD) activity, peroxidase (POD) activity, soluble protein (SP) content, and collar diameter were increased in Longyou 7 as compared to Lenox. A total of 6330 proteins were identified. Among this, 98, 107, 183 and 111 DAPs were expressed in L7 CK/Le CK, L7 d/Le d, Le d/Le CK and L7 d/L7 CK, respectively. Quantitative real-time PCR (RT-qPCR) analysis of the coding genes for seventeen randomly selected DAPs was performed for validation. These DAPs were identified based on gene ontology enrichment analysis, which revealed that glutathione transferase activity, carbohydrate-binding, glutathione binding, metabolic process, and IAA response were closely associated with the cold stress response. In addition, some cold-induced proteins, such as glutathione S-transferase phi 2(GSTF2), might play an essential role during cold acclimation in the SAM of Brassica rapa. The present study provides valuable information on the involvement of DAPs during cold stress responses in Brassica rapa L, and hence could be used for breeding experiments.
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Zhu H, Rollier CS, Pollard AJ. Recent advances in lipopolysaccharide-based glycoconjugate vaccines. Expert Rev Vaccines 2021; 20:1515-1538. [PMID: 34550840 DOI: 10.1080/14760584.2021.1984889] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
INTRODUCTION The public health burden caused by pathogenic Gram-negative bacteria is increasingly prominent due to antimicrobial resistance. The surface carbohydrates are potential antigens for vaccines against Gram-negative bacteria. The enhanced immunogenicity of the O-specific polysaccharide (O-SP) moiety of LPS when coupled to a carrier protein may protect against bacterial pathogens. However, because of the toxic lipid A moiety and relatively high costs of O-SP isolation, LPS has not been a popular vaccine antigen until recently. AREAS COVERED In this review, we discuss the rationales for developing LPS-based glycoconjugate vaccines, principles of glycoconjugate-induced immunity, and highlight the recent developments and challenges faced by LPS-based glycoconjugate vaccines. EXPERT OPINION Advances in LPS harvesting, LPS chemical synthesis, and newer carrier proteins in the past decade have propelled LPS-based glycoconjugate vaccines toward further development, through to clinical evaluation. The development of LPS-based glycoconjugates offers a new horizon for vaccine prevention of Gram-negative bacterial infection.
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Affiliation(s)
- Henderson Zhu
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the National Institute for Health Research (Nihr) Oxford Biomedical Research Centre, Oxford, UK
| | - Christine S Rollier
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the National Institute for Health Research (Nihr) Oxford Biomedical Research Centre, Oxford, UK
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the National Institute for Health Research (Nihr) Oxford Biomedical Research Centre, Oxford, UK
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Reverse vaccinology approach for the identifications of potential vaccine candidates against Salmonella. Int J Med Microbiol 2021; 311:151508. [PMID: 34182206 DOI: 10.1016/j.ijmm.2021.151508] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 03/14/2021] [Accepted: 04/15/2021] [Indexed: 12/26/2022] Open
Abstract
Salmonella is a leading cause of foodborne pathogen which causes intestinal and systemic diseases across the world. Vaccination is the most effective protection against Salmonella, but the identification and design of an effective broad-spectrum vaccine is still a great challenge, because of the multi-serotypes of Salmonella. Reverse vaccinology is a new tool to discovery and design vaccine antigens combining human immunology, structural biology and computational biology with microbial genomics. In this study, reverse vaccinology, an in-silico approach was established to screen appropriate immunogen targets by calculating the immunogenicity score of 583 non-redundant outer membrane and secreted proteins of Salmonella. Herein among 100 proteins identified with top-ranked scores, 15 representative antigens were selected randomly. Applying the sequence conservation test, four proteins (FliK, BcsZ, FhuA and FepA) remained as potential vaccine candidates for in vivo evaluation of immunogenicity and immunoprotection. All four candidates were capable to trigger the immune response and stimulate the production of antiserum in mice. Furthermore, top-ranked proteins including FliK and BcsZ provided wide antigenic coverage among the multi-serotype of Salmonella. The S. Typhimurium LT2 challenge model used in mice immunized with FliK and BcsZ showed a high relative percentage survival (RPS) of 52.74 % and 64.71 % respectively. In conclusion, this study constructed an in-silico pipeline able to successfully pre-screen the vaccine targets characterized by high immunogenicity and protective immunity. We show that reverse vaccinology allowed screening of appropriate broad-spectrum vaccines for Salmonella.
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Micoli F, Bagnoli F, Rappuoli R, Serruto D. The role of vaccines in combatting antimicrobial resistance. Nat Rev Microbiol 2021; 19:287-302. [PMID: 33542518 PMCID: PMC7861009 DOI: 10.1038/s41579-020-00506-3] [Citation(s) in RCA: 183] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2020] [Indexed: 01/29/2023]
Abstract
The use of antibiotics has enabled the successful treatment of bacterial infections, saving the lives and improving the health of many patients worldwide. However, the emergence and spread of antimicrobial resistance (AMR) has been highlighted as a global threat by different health organizations, and pathogens resistant to antimicrobials cause substantial morbidity and death. As resistance to multiple drugs increases, novel and effective therapies as well as prevention strategies are needed. In this Review, we discuss evidence that vaccines can have a major role in fighting AMR. Vaccines are used prophylactically, decreasing the number of infectious disease cases, and thus antibiotic use and the emergence and spread of AMR. We also describe the current state of development of vaccines against resistant bacterial pathogens that cause a substantial disease burden both in high-income countries and in low- and medium-income countries, discuss possible obstacles that hinder progress in vaccine development and speculate on the impact of next-generation vaccines against bacterial infectious diseases on AMR.
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Affiliation(s)
- Francesca Micoli
- grid.425088.3GSK Vaccines Institute for Global Health, Siena, Italy
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Dhara D, Baliban SM, Huo CX, Rashidijahanabad Z, Sears KT, Nick ST, Misra AK, Tennant SM, Huang X. Syntheses of Salmonella Paratyphi A Associated Oligosaccharide Antigens and Development towards Anti-Paratyphoid Fever Vaccines. Chemistry 2020; 26:15953-15968. [PMID: 32578281 PMCID: PMC7722144 DOI: 10.1002/chem.202002401] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/21/2020] [Indexed: 01/08/2023]
Abstract
With the emergence of multidrug resistant Salmonella strains, the development of anti-Salmonella vaccines is an important task. Currently there are no approved vaccines against Salmonella Paratyphi A, the leading cause of paratyphoid fever. To fill this gap, oligosaccharides corresponding to the O-polysaccharide repeating units from the surface of Salmonella Paratyphi A have been synthesized through convergent stereoselective glycosylations. The synthetic glycan antigen was conjugated with a powerful immunogenic carrier system, the bacteriophage Qβ. The resulting construct was able to elicit strong and long-lasting anti-glycan IgG antibody responses, which were highly selective toward Salmonella Paratyphi A associated glycans. The availability of well-defined glycan antigen enabled the determination that one repeating unit of the polysaccharide is sufficient to induce protective antibodies, and the paratose residue and/or the O-acetyl modifications on the backbone are important for recognition by antibodies elicited by a Qβ-tetrasaccharide conjugate. Immune sera provided excellent protection to mice from lethal challenge with Salmonella Paratyphi A, highlighting the potential of the synthetic glycan-based vaccine.
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Affiliation(s)
- Debashis Dhara
- Division of Molecular Medicine; Bose Institute, P-1/12, C.I.T. Scheme VII M; Kolkata 700054, India
| | - Scott M. Baliban
- Center for Vaccine Development and Global Health; University of Maryland School of Medicine; Baltimore, MD, USA
| | - Chang-Xin Huo
- Department of Chemistry, Michigan State University; 578 South Shaw Lane, East Lansing, MI 48824, USA
- Institute for Quantitative Health Science & Engineering; Michigan State University; 578 South Shaw Lane, East Lansing, MI 48824, USA
| | - Zahra Rashidijahanabad
- Department of Chemistry, Michigan State University; 578 South Shaw Lane, East Lansing, MI 48824, USA
- Institute for Quantitative Health Science & Engineering; Michigan State University; 578 South Shaw Lane, East Lansing, MI 48824, USA
| | - Khandra T. Sears
- Center for Vaccine Development and Global Health; University of Maryland School of Medicine; Baltimore, MD, USA
| | - Setare Tahmasebi Nick
- Department of Chemistry, Michigan State University; 578 South Shaw Lane, East Lansing, MI 48824, USA
- Institute for Quantitative Health Science & Engineering; Michigan State University; 578 South Shaw Lane, East Lansing, MI 48824, USA
| | - Anup Kumar Misra
- Division of Molecular Medicine; Bose Institute, P-1/12, C.I.T. Scheme VII M; Kolkata 700054, India
| | - Sharon M. Tennant
- Center for Vaccine Development and Global Health; University of Maryland School of Medicine; Baltimore, MD, USA
| | - Xuefei Huang
- Department of Chemistry, Michigan State University; 578 South Shaw Lane, East Lansing, MI 48824, USA
- Institute for Quantitative Health Science & Engineering; Michigan State University; 578 South Shaw Lane, East Lansing, MI 48824, USA
- Department of Biomedical Engineering; Michigan State University; East Lansing, MI 48824, USA
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Baliban SM, Lu YJ, Malley R. Overview of the Nontyphoidal and Paratyphoidal Salmonella Vaccine Pipeline: Current Status and Future Prospects. Clin Infect Dis 2020; 71:S151-S154. [PMID: 32725233 PMCID: PMC7388718 DOI: 10.1093/cid/ciaa514] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Nontyphoidal Salmonella and Salmonella Paratyphi are responsible for significant morbidity and mortality worldwide. To date, no vaccine has been licensed against these organisms. The development of effective vaccines remains an urgent priority. In this review, the rationale for and current status of various vaccine candidates against S. Paratyphi and nontyphoidal Salmonella are presented, with a focus on the research findings from the 2019 International Conference on Typhoid and Other Invasive Salmonelloses. Additionally, other vaccine candidates that are currently undergoing clinical development are highlighted. Future approaches, which may include antigens that are genetically conserved across Salmonella and confer broad, non-serotype-specific protection, are also discussed.
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Affiliation(s)
- Scott M Baliban
- Center for Vaccine Development and Global Health, University of Maryland, School of Medicine, Baltimore, Maryland, USA
| | - Ying-Jie Lu
- Division of Infectious Diseases, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Richard Malley
- Division of Infectious Diseases, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
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O'Reilly PJ, Pant D, Shakya M, Basnyat B, Pollard AJ. Progress in the overall understanding of typhoid fever: implications for vaccine development. Expert Rev Vaccines 2020; 19:367-382. [PMID: 32238006 DOI: 10.1080/14760584.2020.1750375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Typhoid fever continues to have a substantial impact on human health, especially in Asia and sub-Saharan Africa. Access to safe water, and adequate sanitation and hygiene remain the cornerstone of prevention, but these are not widely available in many impoverished settings. The emergence of antibiotic resistance affects typhoid treatment and adds urgency to typhoid control efforts. Vaccines provide opportunities to prevent and control typhoid fever in endemic settings. AREAS COVERED Literature search was performed looking for evidence concerning the global burden of typhoid and strategies for the prevention and treatment of typhoid fever. Cost of illness, available typhoid and paratyphoid vaccines and cost-effectiveness were also reviewed. The objective was to provide a critical overview of typhoid fever, in order to assess the current understanding and potential future directions for typhoid treatment and control. EXPERT COMMENTARY Our understanding of typhoid burden and methods of prevention has grown over recent years. However, typhoid fever still has a significant impact on health in low and middle-income countries. Introduction of typhoid conjugate vaccines to the immunization schedule is expected to make a major contribution to control of typhoid fever in endemic countries, although vaccination alone is unlikely to eliminate the disease.
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Affiliation(s)
- Peter J O'Reilly
- Oxford Vaccine Group, Department of Pediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre , Oxford, UK
| | - Dikshya Pant
- Department of Paediatrics, Patan Academy of Health Sciences, Patan Hospital , Kathmandu, Nepal
| | - Mila Shakya
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences , Kathmandu, Nepal
| | - Buddha Basnyat
- Oxford University Clinical Research Unit, Patan Academy of Health Sciences , Kathmandu, Nepal
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Pediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre , Oxford, UK
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12
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Liu Q, Li P, Luo H, Curtiss R, Kong Q. Attenuated Salmonella Typhimurium expressing Salmonella Paratyphoid A O-antigen induces protective immune responses against two Salmonella strains. Virulence 2019; 10:82-96. [PMID: 31874075 PMCID: PMC6363073 DOI: 10.1080/21505594.2018.1559673] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 11/26/2018] [Accepted: 12/09/2018] [Indexed: 12/17/2022] Open
Abstract
Salmonella enterica serovar Paratyphi A is the main causative agent of paratyphoid fever in many Asian countries. As paratyphoid is spread by the fecal-oral route, the most effective means of controlling S. Paratyphi A infection is through the availability of clean water supplies and working sanitation services. Because sanitation facilities improve slowly in these poor areas and antibiotic resistance is severe, the development of a safe and effective vaccine remains a priority for controlling the spread of paratyphoid disease. In this study, we investigated the strategy of heterologous O-antigenic O2 serotype (S. Paratyphi A characterized) conversion in S. Typhimurium to prevent paratyphoid infections. A series of S. Typhimurium mutants were constructed with replacement of abe, wzxB1 and wbaVB1 genes with respective prt-tyvA1, wzxA1 and wbaVA1, and the results showed that only three genes including prt, wbaVA1 and wzxA1 from S. Paratyphi A presence enable S. Typhimurium to sufficiently express O2 antigen polysaccharide. We also constructed a series of live attenuated S. Typhimurium vaccine candidates expressing heterologous O2 O-antigens, and a mouse model was used to evaluate the immunogenicity of live vaccines. ELISA data showed that vaccine candidates could induce a comparatively high level of S. Paratyphi A and/or S. Typhimurium LPS-specific IgG and IgA responses in murine model, and IgG2a levels were consistently higher than IgG1 levels. Moreover, the functional properties of serum antibodies were evaluated using in vitro C3 complement deposition and opsonophagocytic assays. Our work highlights the potential for developing S. Typhimurium live vaccines against S. Paratyphi A.
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Affiliation(s)
- Qing Liu
- College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Pei Li
- College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Hongyan Luo
- College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Roy Curtiss
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, FL, USA
| | - Qingke Kong
- College of Animal Science and Technology, Southwest University, Chongqing, China
- Department of Infectious Diseases and Immunology, University of Florida, Gainesville, FL, USA
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13
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Salerno-Goncalves R, Kayastha D, Fasano A, Levine MM, Sztein MB. Crosstalk between leukocytes triggers differential immune responses against Salmonella enterica serovars Typhi and Paratyphi. PLoS Negl Trop Dis 2019; 13:e0007650. [PMID: 31412039 PMCID: PMC6709971 DOI: 10.1371/journal.pntd.0007650] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 08/26/2019] [Accepted: 07/23/2019] [Indexed: 12/30/2022] Open
Abstract
Enteric fevers, caused by the Salmonella enterica serovars Typhi (ST), Paratyphi A (PA) and Paratyphi B (PB), are life-threatening illnesses exhibiting very similar clinical symptoms but with distinct epidemiologies, geographical distributions and susceptibilities to antimicrobial treatment. Nevertheless, the mechanisms by which the host recognizes pathogens with high levels of homology, such as these bacterial serovars, remain poorly understood. Using a three-dimensional organotypic model of the human intestinal mucosa and PA, PB, and ST, we observed significant differences in the secretion patterns of pro-inflammatory cytokines and chemokines elicited by these serovars. These cytokines/chemokines were likely to be co-regulated and influenced the function of epithelial cells, such as the production of IL-8. We also found differing levels of polymorphonuclear leukocyte (PMN) migration among various infection conditions that either included or excluded lymphocytes and macrophages (Mϕ), strongly suggesting feedback mechanisms among these cells. Blocking experiments showed that IL-1β, IL-6, IL-8, TNF-α and CCL3 cytokines were involved in the differential regulation of migration patterns. We conclude that the crosstalk among the lymphocytes, Mϕ, PMN and epithelial cells is cytokine/chemokine-dependent and bacterial-serotype specific, and plays a pivotal role in orchestrating the functional efficiency of the innate cells and migratory characteristics of the leukocytes.
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Affiliation(s)
- Rosangela Salerno-Goncalves
- Center for Vaccine Development and Global Health, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Darpan Kayastha
- Center for Vaccine Development and Global Health, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Alessio Fasano
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital for Children, Boston, MA, United States of America
| | - Myron M. Levine
- Center for Vaccine Development and Global Health, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Marcelo B. Sztein
- Center for Vaccine Development and Global Health, Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States of America
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14
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Wahid R, Kotloff KL, Levine MM, Sztein MB. Cell mediated immune responses elicited in volunteers following immunization with candidate live oral Salmonella enterica serovar Paratyphi A attenuated vaccine strain CVD 1902. Clin Immunol 2019; 201:61-69. [PMID: 30849494 DOI: 10.1016/j.clim.2019.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 02/22/2019] [Accepted: 03/03/2019] [Indexed: 01/01/2023]
Abstract
The incidence of Salmonella enterica serovar Paratyphi A (PA) infection is on the rise and no licensed vaccines are available. We evaluated cell mediated immune (CMI) responses elicited in volunteers following immunization with a single dose (109 or 1010 cfu) of a novel attenuated live oral PA-vaccine strain (CVD 1902). Results showed increases in PA-lipopolysaccharide-specific IgG- and/or IgA B-memory cells and production of IFN-γ, TNF-α, IL-10, IL-23 and RANTES following stimulation with PA-antigens by peripheral blood mononuclear cells obtained 28 days post immunization. Flow cytometry assays revealed that vaccine elicited PA-specific CD8+ and/or CD4+ T effector/memory cells were predominantly multifunctional concomitantly expressing CD107a and/or producing IFN-γ, TNF-α and/or IL-2. Similar proportions of these MF cells expressed, or not, the gut homing marker integrin α4β7. The results suggest that immunization with CVD 1902 elicits CMI responses against PA supporting its further evaluation as a potential vaccine candidate against paratyphoid A fever.
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Affiliation(s)
- Rezwanul Wahid
- Department of Pediatrics, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Karen L Kotloff
- Department of Pediatrics, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Medicine, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Myron M Levine
- Department of Pediatrics, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Medicine, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Marcelo B Sztein
- Department of Pediatrics, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Medicine, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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Improving Our Understanding of Salmonella enterica Serovar Paratyphi B through the Engineering and Testing of a Live Attenuated Vaccine Strain. mSphere 2018; 3:3/6/e00474-18. [PMID: 30487152 PMCID: PMC6262260 DOI: 10.1128/msphere.00474-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We developed a live attenuated Salmonella enterica serovar Paratyphi B vaccine that conferred protection in mice against challenge with S. Paratyphi B sensu stricto and S. Paratyphi B Java, which are the causes of enteric fever and gastroenteritis, respectively. Currently, the incidence of invasive S. Paratyphi B sensu stricto infections is low; however, the development of new conjugate vaccines against other enteric fever serovars could lead to the emergence of S. Paratyphi B to fill the niche left by these other pathogens. As such, an effective S. Paratyphi B vaccine would be a useful tool in the armamentarium against Salmonella infections. Comparative genomics confirmed the serovar-specific groupings of these isolates and revealed that there are a limited number of genetic differences between the sensu stricto and Java strains, which are mostly hypothetical and phage-encoded proteins. The observed level of genomic similarity likely explains why we observe some cross-protection. Enteric fever is caused by three Salmonella enterica serovars: Typhi, Paratyphi A, and Paratyphi B sensu stricto. Although vaccines against two of these serovars are licensed (Typhi) or in clinical development (Paratyphi A), as yet there are no candidates for S. Paratyphi B. To gain genomic insight into these serovars, we sequenced 38 enteric fever-associated strains from Chile and compared these with reference genomes. Each of the serovars was separated genomically based on the core genome. Genomic comparisons identified loci that were aberrant between serovars Paratyphi B sensu stricto and Paratyphi B Java, which is typically associated with gastroenteritis; however, the majority of these were annotated as hypothetical or phage related and thus were not ideal vaccine candidates. With the genomic information in hand, we engineered a live attenuated S. Paratyphi B sensu stricto vaccine strain, CVD 2005, which was capable of protecting mice from both homologous challenge and heterologous challenge with S. Paratyphi B Java. These findings extend our understanding of S. Paratyphi B and provide a viable vaccine option for inclusion in a trivalent live attenuated enteric fever vaccine formulation. IMPORTANCE We developed a live attenuated Salmonella enterica serovar Paratyphi B vaccine that conferred protection in mice against challenge with S. Paratyphi B sensu stricto and S. Paratyphi B Java, which are the causes of enteric fever and gastroenteritis, respectively. Currently, the incidence of invasive S. Paratyphi B sensu stricto infections is low; however, the development of new conjugate vaccines against other enteric fever serovars could lead to the emergence of S. Paratyphi B to fill the niche left by these other pathogens. As such, an effective S. Paratyphi B vaccine would be a useful tool in the armamentarium against Salmonella infections. Comparative genomics confirmed the serovar-specific groupings of these isolates and revealed that there are a limited number of genetic differences between the sensu stricto and Java strains, which are mostly hypothetical and phage-encoded proteins. The observed level of genomic similarity likely explains why we observe some cross-protection.
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Why Is Eradicating Typhoid Fever So Challenging: Implications for Vaccine and Therapeutic Design. Vaccines (Basel) 2018; 6:vaccines6030045. [PMID: 30042307 PMCID: PMC6160957 DOI: 10.3390/vaccines6030045] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 07/19/2018] [Accepted: 07/23/2018] [Indexed: 01/22/2023] Open
Abstract
Salmonella enterica serovar Typhi (S. Typhi) and S. Paratyphi, namely typhoidal Salmonellae, are the cause of (para) typhoid fever, which is a devastating systemic infectious disease in humans. In addition, the spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) S. Typhi in many low and middle-income countries poses a significant risk to human health. While currently available typhoid vaccines and therapeutics are efficacious, they have some limitations. One important limitation is the lack of controlling individuals who chronically carry S. Typhi. However, due to the strict host specificity of S. Typhi to humans, S. Typhi research is hampered. As a result, our understanding of S. Typhi pathogenesis is incomplete, thereby delaying the development and improvement of prevention and treatment strategies. Nonetheless, to better combat and contain S. Typhi, it is vital to develop a vaccine and therapy for controlling both acutely and chronically infected individuals. This review discusses how scientists are trying to combat typhoid fever, why it is so challenging to do so, which approaches show promise, and what we know about the pathogenesis of S. Typhi chronic infection.
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17
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Fuche FJ, Jones JA, Ramachandran G, Higginson EE, Simon R, Tennant SM. Deletions in guaBA and htrA but not clpX or rfaL constitute a live-attenuated vaccine strain of Salmonella Newport to protect against serogroup C 2-C 3 Salmonella in mice. Hum Vaccin Immunother 2018; 15:1427-1435. [PMID: 29927725 PMCID: PMC6663134 DOI: 10.1080/21645515.2018.1491499] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Non-typhoidal Salmonella (NTS) are a leading cause of foodborne infections worldwide, and serogroups B, C1, C2-C3 and D are the most common serogroups associated with human disease. While live vaccine candidates that protect against S. Typhimurium (serogroup B) and S. Enteritidis (serogroup D) have been described by us and others, far less effort has been directed towards vaccines that target either serogroup C1 or C2-C3Salmonella. Here we describe a Salmonella Newport-based live-attenuated vaccine (serogroup C2-C3). Deletion of the genes clpX or rfaL, previously used in live vaccines to attenuate S. Typhimurium and/or S. Enteritidis, failed to attenuate S. Newport. However, we found that deletion of either guaBA or htrA raised the 50% lethal dose of S. Newport in an intraperitoneal infection model in BALB/c mice. Our live-attenuated vaccine candidate CVD 1966 (S. Newport ΔguaBA ΔhtrA) elicited strong antibody responses against COPS, flagellin and outer membrane proteins when administered intraperitoneally or orally. Following lethal challenge with the parental virulent strain of S. Newport, we observed vaccine efficacies of 53% for immunization via the intraperitoneal route and 47% for immunization via the oral route. Following intraperiteonal immunization, the vaccine also significantly reduced the bacterial burden of challenge organisms in the liver and spleen. Interestingly, reducing the LPS chain length by deleting rfaL did not induce a stronger immune response towards surface antigens, and failed to elicit any protection against lethal homologous challenge. In conclusion, we have developed a live-attenuated Salmonella serogroup C2-C3 vaccine that we are further evaluating.
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Affiliation(s)
- Fabien J Fuche
- a Center for Vaccine Development and Institute for Global Health, Department of Medicine , University of Maryland School of Medicine , Baltimore , MD , USA
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18
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Necchi F, Saul A, Rondini S. Setup of luminescence-based serum bactericidal assay against Salmonella Paratyphi A. J Immunol Methods 2018; 461:117-121. [PMID: 29969587 DOI: 10.1016/j.jim.2018.06.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Revised: 06/10/2018] [Accepted: 06/29/2018] [Indexed: 10/28/2022]
Abstract
Increasing awareness of Salmonella Paratyphi A's contribution to enteric fever episodes throughout Asia has led to the development of new S. Paratyphi A vaccines. Assays are needed to measure functional antibodies elicited by the new vaccine candidates to assess their immunogenicity and potential protective capacities. Serum bactericidal assay (SBA) is the method of choice to measure functional antibody titers against various bacterial pathogens, but it is rarely been used for large dataset and clinical samples because it is time consuming and labor-intensive. Recently we developed a high-throughput luminescence-based SBA method, against different pathogens, including Salmonella Typhimurium and Enteritidis, Shigella flexneri serovars 2a and 3a, Shigella sonnei and Neisseria meningitidis. Here we further demonstrated the applicability of such method with invasive isolates of S. Paratyphi A to assess the complement-mediated antibody-dependent killing of both preclinical and clinical standard sera. As already found for other organisms, titers obtained by the luminescence-based SBA strongly correlated with those obtained by the conventional agar plate-based assay. The SBA assay described here is a useful tool for measuring functional antibodies elicited by Salmonella vaccines, with the potential of being applied to immunogenicity assessment in clinical trials.
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Affiliation(s)
- Francesca Necchi
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy.
| | - Allan Saul
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy
| | - Simona Rondini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy
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19
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Arnold KB, Chung AW. Prospects from systems serology research. Immunology 2017; 153:279-289. [PMID: 29139548 PMCID: PMC5795183 DOI: 10.1111/imm.12861] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/02/2017] [Accepted: 11/04/2017] [Indexed: 12/28/2022] Open
Abstract
Antibodies are highly functional glycoproteins capable of providing immune protection through multiple mechanisms, including direct pathogen neutralization and the engagement of their Fc portions with surrounding effector immune cells that induce anti-pathogenic responses. Small modifications to multiple antibody biophysical features induced by vaccines can significantly alter functional immune outcomes, though it is difficult to predict which combinations confer protective immunity. In order to give insight into the highly complex and dynamic processes that drive an effective humoral immune response, here we discuss recent applications of 'Systems Serology', a new approach that uses data-driven (also called 'machine learning') computational analysis and high-throughput experimental data to infer networks of important antibody features associated with protective humoral immunity and/or Fc functional activity. This approach offers the ability to understand humoral immunity beyond single correlates of protection, assessing the relative importance of multiple biophysical modifications to antibody features with multivariate computational approaches. Systems Serology has the exciting potential to help identify novel correlates of protection from infection and may generate a more comprehensive understanding of the mechanisms behind protection, including key relationships between specific Fc functions and antibody biophysical features (e.g. antigen recognition, isotype, subclass and/or glycosylation events). Reviewed here are some of the experimental and computational technologies available for Systems Serology research and evidence that the application has broad relevance to multiple different infectious diseases including viruses, bacteria, fungi and parasites.
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Affiliation(s)
- Kelly B Arnold
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Amy W Chung
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Vic., Australia
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20
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Animal Models for Salmonellosis: Applications in Vaccine Research. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2016; 23:746-56. [PMID: 27413068 DOI: 10.1128/cvi.00258-16] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Salmonellosis remains an important cause of human disease worldwide. While there are several licensed vaccines for Salmonella enterica serovar Typhi, these vaccines are generally ineffective against other Salmonella serovars. Vaccines that target paratyphoid and nontyphoidal Salmonella serovars are very much in need. Preclinical evaluation of candidate vaccines is highly dependent on the availability of appropriate scientific tools, particularly animal models. Many different animal models exist for various Salmonella serovars, from whole-animal models to smaller models, such as those recently established in insects. Here, we discuss various mouse, rat, rabbit, calf, primate, and insect models for Salmonella infection, all of which have their place in research. However, choosing the right model is imperative in selecting the best vaccine candidates for further clinical testing. In this minireview, we summarize the various animal models that are used to assess salmonellosis, highlight some of the advantages and disadvantages of each, and discuss their value in vaccine development.
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21
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Opsonophagocytic Assay To Evaluate Immunogenicity of Nontyphoidal Salmonella Vaccines. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2016; 23:520-523. [PMID: 27030587 DOI: 10.1128/cvi.00106-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 03/23/2016] [Indexed: 11/20/2022]
Abstract
Nontyphoidal Salmonella (NTS) invasive infections are an important cause of morbidity and mortality in sub-Saharan Africa. Several vaccines are in development to prevent these infections. We describe an NTS opsonophagocytic killing assay that uses HL-60 cells and baby rabbit complement to quantify functional antibodies elicited by candidate NTS vaccines.
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22
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Zhu C, Xiong K, Chen Z, Hu X, Li J, Wang Y, Rao X, Cong Y. Construction of an attenuated Salmonella enterica serovar Paratyphi A vaccine strain harboring defined mutations in htrA and yncD. Microbiol Immunol 2016; 59:443-51. [PMID: 26084199 DOI: 10.1111/1348-0421.12276] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 06/09/2015] [Accepted: 06/12/2015] [Indexed: 11/27/2022]
Abstract
The global epidemic features of enteric fever have changed greatly in recent years. The incidence of enteric fever caused by Salmonella enterica serovar Paratyphi A has progressively increased. In some areas of Asia, infections with S. Paratyphi A have exceeded those with S. Typhi, resulting in S. Paratyphi A becoming the main causative agent of enteric fever. However, two currently licensed typhoid vaccines do not confer adequate cross-protection against S. Paratyphi A infection. Therefore, development of specific vaccines against enteric fever caused by S. Paratyphi A is urgently needed. In the present study, an attenuated strain was constructed by double deletion of the htrA and yncD genes in a wild-type strain of S. Paratyphi A and its safety and immunogenicity assessed. In a mouse model, the 50% lethal dose of the double deletion mutant and the wild-type strain were 3.0 × 10(8) CFU and 1.9 × 10(3) CFU, respectively, suggesting that the double deletion resulted in remarkably decreased bacterial virulence. Bacterial colonization of the double deletion mutant in the livers and spleens of infected mice was strikingly less than that of the wild-type strain. A single nasal administration of the attenuated vaccine candidate elicited high concentrations of anti-LPS and anti-flagellin IgG in a mouse model and protected immunized mice against lethal challenge with the wild-type strain. Thus, our findings suggest that the attenuated vaccine strain is a promising candidate worthy of further evaluation both as a human enteric fever vaccine and as a vaccine delivery vector for heterologous antigens.
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Affiliation(s)
- Chunyue Zhu
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
| | - Kun Xiong
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
| | - Zhijin Chen
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
| | - Xiaomei Hu
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
| | - Jianhua Li
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
| | - Yiran Wang
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
| | - Xiancai Rao
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
| | - Yanguang Cong
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, China
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23
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Principi N, Esposito S. Preventing invasive salmonellosis in children through vaccination. Expert Rev Vaccines 2016; 15:897-905. [PMID: 27140662 DOI: 10.1080/14760584.2016.1183484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Vaccination is an important strategy to control endemic enteric fever (EF) and to interrupt transmission during outbreaks. The main aim of this paper is to discuss the efficacy of available EF vaccines in children and to highlight novel vaccination possibilities against EF and non-typhoid invasive salmonelloses. AREAS COVERED Two types of typhoid vaccines are presently available in the industrialized world. One of these vaccines is administered parenterally and is based on the virulence-associated (Vi) capsular polysaccaride of Salmonella typhi. The second vaccine is based on a live attenuated strain of the pathogen and is given orally. In addition, a Vi-tetanus toxoid conjugated vaccine is currently licensed in India; however, it is not available anywhere else. Expert commentary: Unfortunately, only typhoid fever is addressed by the currently licensed typhoid vaccines. Moreover, they are unsuitable for infants and remain a possible aid for reducing the risk of EF only in older subjects. They should be used in developing countries with endemic EF. New vaccines able to confer long-term protection to subjects in the first years of life and those with immature immune systems could significantly reduce incidence rates of EF in younger children. Vi-conjugate preparations are promising solutions in this regard.
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Affiliation(s)
- Nicola Principi
- a Paediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation , Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico , Milan , Italy
| | - Susanna Esposito
- a Paediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation , Università degli Studi di Milano, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico , Milan , Italy
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24
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Martin LB, Simon R, MacLennan CA, Tennant SM, Sahastrabuddhe S, Khan MI. Status of paratyphoid fever vaccine research and development. Vaccine 2016; 34:2900-2902. [PMID: 27083427 DOI: 10.1016/j.vaccine.2016.03.106] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 03/30/2016] [Indexed: 01/08/2023]
Abstract
Salmonella enterica serovars Typhi and Paratyphi (S. Paratyphi) A and B cause enteric fever in humans. Of the paratyphoid group, S. Paratyphi A is the most common serovar. In 2000, there were an estimated 5.4 million cases of S. Paratyphi A worldwide. More recently paratyphoid fever has accounted for an increasing fraction of all cases of enteric fever. Although vaccines for typhoid fever have been developed and in use for decades, vaccines for paratyphoid fever have not yet been licensed. Several S. Paratyphi A vaccines, however, are in development and based on either whole cell live-attenuated strains or repeating units of the lipopolysaccharide O-antigen (O:2) conjugated to different protein carriers. An O-specific polysaccharide (O:2) of S. Paratyphi A conjugated to tetanus toxoid (O:2-TT), for example, has been determined to be safe and immunogenic after one dose in Phase I and Phase II trials. Two other conjugated vaccine candidates linked to diphtheria toxin and a live-attenuated oral vaccine candidate are currently in preclinical development. As promising vaccine candidates are advanced along the development pipeline, an adequate supply of vaccines will need to be ensured to meet growing demand, particularly in the most affected countries.
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Affiliation(s)
- Laura B Martin
- GSK Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
| | - Raphael Simon
- Center for Vaccine Development and Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Calman A MacLennan
- Jenner Institute, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford OX3 7DQ, United Kingdom; Wellcome Trust Sanger Institute, Wellcome Trust Genomes Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - Sharon M Tennant
- Center for Vaccine Development and Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - M Imran Khan
- Center of Excellence for Women and Child Health, The Aga Khan University, Stadium Road, Karachi 74800, Pakistan.
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25
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Goh YS, Armour KL, Clark MR, Grant AJ, Mastroeni P. Igg Subclasses Targeting the Flagella of Salmonella enterica Serovar Typhimurium Can Mediate Phagocytosis and Bacterial Killing. ACTA ACUST UNITED AC 2016; 7. [PMID: 27366588 DOI: 10.4172/2157-7560.1000322] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Invasive non-typhoidal Salmonella are a common cause of invasive disease in immuno-compromised individuals and in children. Multi-drug resistance poses challenges to disease control, with a critical need for effective vaccines. Flagellin is an attractive vaccine candidate due to surface exposure and high epitope copy number, but its potential as a target for opsonophacytic antibodies is unclear. We examined the effect of targeting flagella with different classes of IgG on the interaction between Salmonella Typhimurium and a human phagocyte-like cell line, THP-1. We tagged the FliC flagellar protein with a foreign CD52 mimotope (TSSPSAD) and bacteria were opsonized with a panel of humanised CD52 antibodies with the same antigen-binding V-region, but different constant regions. We found that IgG binding to flagella increases bacterial phagocytosis and reduces viable intracellular bacterial numbers. Opsonisation with IgG3, followed by IgG1, IgG4, and IgG2, resulted in the highest level of bacterial uptake and in the highest reduction in the intracellular load of viable bacteria. Taken together, our data provide proof-of-principle evidence that targeting flagella with antibodies can increase the antibacterial function of host cells, with IgG3 being the most potent subclass. These data will assist the rational design of urgently needed, optimised vaccines against iNTS disease.
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Affiliation(s)
- Yun Shan Goh
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom
| | - Kathryn L Armour
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom
| | - Michael R Clark
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, United Kingdom
| | - Andrew J Grant
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom
| | - Pietro Mastroeni
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom
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26
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Xiong K, Chen Z, Zhu C, Li J, Hu X, Rao X, Cong Y. Safety and immunogenicity of an attenuated Salmonella enterica serovar Paratyphi A vaccine candidate. Int J Med Microbiol 2015; 305:563-71. [PMID: 26239100 DOI: 10.1016/j.ijmm.2015.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 07/02/2015] [Accepted: 07/22/2015] [Indexed: 02/08/2023] Open
Abstract
Enteric fever caused by Salmonella enterica serovar Paratyphi A has progressively increased in recent years and became a global health issue. Currently licensed typhoid vaccines do not confer adequate cross-immunoprotection against S. Paratyphi A infection. Therefore, vaccines specifically against enteric fever caused by S. Paratyphi A are urgently needed. In the present study, an attenuated vaccine strain was constructed from S. Paratyphi A CMCC50093 by the deletions of aroC and yncD. The obtained strain SPADD01 showed reduced survival within THP-1 cells and less bacterial burden in spleens and livers of infected mice compared with the wild-type strain. The 50% lethal doses of SPADD01 and the wild-type strain were assessed using a murine infection model. The virulence of SPADD01 is approximately 40,000-fold less than that of the wild-type strain. In addition, SPADD01 showed an excellent immunogenicity in mouse model. Single intranasal inoculation elicited striking humoral and mucosal immune responses in mice and yielded effective protection against lethal challenge of the wild-type strain. A high level of cross-reactive humoral immune response against LPS of Salmonella enterica serovar Typhi was also detected in immunized mice. However, SPADD01 vaccination only conferred a low level of cross-protection against S. Typhi. Our data suggest that SPADD01 is a promising vaccine candidate against S. Paratyphi A infection and deserves further evaluation in clinical trial. To date, no study has demonstrated a good cross-protection between serovars of S. Typhi and S. Paratyphi A, suggesting that the dominant protective antigens of both serovars are likely different and need to be defined in future study.
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Affiliation(s)
- Kun Xiong
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, PR China.
| | - Zhijin Chen
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, PR China.
| | - Chunyue Zhu
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, PR China.
| | - Jianhua Li
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, PR China.
| | - Xiaomei Hu
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, PR China.
| | - Xiancai Rao
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, PR China.
| | - Yanguang Cong
- Department of Microbiology, Third Military Medical University, Chongqing, 400038, PR China.
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Montanaro J, Inic-Kanada A, Ladurner A, Stein E, Belij S, Bintner N, Schlacher S, Schuerer N, Mayr UB, Lubitz W, Leisch N, Barisani-Asenbauer T. Escherichia coli Nissle 1917 bacterial ghosts retain crucial surface properties and express chlamydial antigen: an imaging study of a delivery system for the ocular surface. DRUG DESIGN DEVELOPMENT AND THERAPY 2015; 9:3741-54. [PMID: 26229437 PMCID: PMC4516183 DOI: 10.2147/dddt.s84370] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
To target chronic inflammatory ocular surface diseases, a drug delivery platform is needed that is safe, possesses immunomodulatory properties, and can be used either for drug delivery, or as a foreign antigen carrier. A new therapeutic approach that we have previously proposed uses nonliving bacterial ghosts (BGs) as a carrier-delivery system which can be engineered to carry foreign antigens and/or be loaded with therapeutic drugs. The parent strain chosen for development of our BG delivery system is the probiotic Escherichia coli strain Nissle 1917 (EcN), whose intrinsic properties trigger the innate immune system with the flagella and fimbriae used to attach and stimulate epithelial cells. In previous studies, we have shown that EcN BGs are safe for the ocular surface route, but evidence that EcN BGs retain flagella and fimbriae after transformation, has never been visually confirmed. In this study, we used different visualization techniques to determine whether flagella and fimbriae are retained on EcN BGs engineered either for drug delivery or as a foreign antigen carrier. We have also shown by immunoelectron microscopy that EcN retains two foreign antigens after processing to become EcN BGs. Furthermore, we demonstrated that BGs derived from EcN and expressing a foreign antigen attachment to conjunctival epithelial cells in vitro without causing reduced cell viability. These results are an important step in constructing a delivery system based on a nonliving probiotic that is suitable for use in ocular surface diseases pairing immunomodulation and targeted delivery.
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Affiliation(s)
- Jacqueline Montanaro
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
| | - Aleksandra Inic-Kanada
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
| | - Angela Ladurner
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
| | - Elisabeth Stein
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
| | - Sandra Belij
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
| | - Nora Bintner
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
| | - Simone Schlacher
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
| | - Nadine Schuerer
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
| | | | | | - Nikolaus Leisch
- Department of Ecogenomics and Systems Biology, University of Vienna, Vienna, Austria
| | - Talin Barisani-Asenbauer
- Laura Bassi Centres of Expertise, OCUVAC - Centre of Ocular Inflammation and Infection, Centre for Pathophysiology, Infectiology, and Immunology, Medical University of Vienna, Vienna, Austria
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McCullagh D, Dobinson HC, Darton T, Campbell D, Jones C, Snape M, Stevens Z, Plested E, Voysey M, Kerridge S, Martin LB, Angus B, Pollard AJ. Understanding paratyphoid infection: study protocol for the development of a human model of Salmonella enterica serovar Paratyphi A challenge in healthy adult volunteers. BMJ Open 2015; 5:e007481. [PMID: 26082464 PMCID: PMC4480031 DOI: 10.1136/bmjopen-2014-007481] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 01/09/2023] Open
Abstract
INTRODUCTION This study will develop the first human challenge model of paratyphoid infection which may then be taken forward to evaluate paratyphoid vaccine candidates. Salmonella Paratyphi A is believed to cause a quarter of the estimated 20 million cases of enteric fever annually. Epidemiological evidence also suggests that an increasing proportion of the enteric fever burden is attributable to S. Paratyphi infection meriting further attention and interest in vaccine development. Assessment of paratyphoid vaccine efficacy in preclinical studies is complicated by the lack of a small animal model and the human-restricted nature of the infection. The use of experimental human infection in healthy volunteers provides an opportunity to address these problems in a cost-effective manner. METHODS AND ANALYSIS Volunteers will ingest virulent S. Paratyphi A bacteria (NVGH308 strain) with a bicarbonate buffer solution to establish the infectious dose resulting in an 'attack rate' of 60-75%. Using an a priori decision-making algorithm, the challenge dose will be escalated or de-escalated to achieve the target attack rate, with the aim of reaching the study end point while exposing as few individuals as possible to infection. The attack rate will be determined by the proportion of paratyphoid infection in groups of 20 healthy adult volunteers, with infection being defined by one or more positive blood cultures (microbiological end point) and/or fever, defined as an oral temperature exceeding 38 °C sustained for at least 12 h (clinical end point); 20-80 participants will be required. Challenge participants will start a 2-week course of an oral antibiotic on diagnosis of infection, or after 14 days follow-up. ETHICS AND DISSEMINATION The strict eligibility criterion aims to minimise risk to participants and their close contacts. Ethical approval has been obtained. The results will be disseminated in a peer-reviewed journal and presented at international congresses. TRIAL REGISTRATION NUMBER NCT02100397.
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Affiliation(s)
- David McCullagh
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Hazel C Dobinson
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Thomas Darton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Danielle Campbell
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Claire Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Matthew Snape
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Zoe Stevens
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Emma Plested
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Merryn Voysey
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
- Primary Care Clinical Trials Unit, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, Oxfordshire, UK
| | - Simon Kerridge
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
| | - Laura B Martin
- Novartis Vaccines Institute for Global Health, Siena, Italy
| | - Brian Angus
- Nuffield Department of Medicine, University of Oxford, Oxford, Oxfordshire, UK
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, and the NIHR Oxford Biomedical Research Centre, Oxford, Oxfordshire, UK
- Primary Care Clinical Trials Unit, Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, Oxfordshire, UK
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Stepanova LA, Kotlyarov RY, Kovaleva AA, Potapchuk MV, Korotkov AV, Sergeeva MV, Kasianenko MA, Kuprianov VV, Ravin NV, Tsybalova LM, Skryabin KG, Kiselev OI. Protection against multiple influenza A virus strains induced by candidate recombinant vaccine based on heterologous M2e peptides linked to flagellin. PLoS One 2015; 10:e0119520. [PMID: 25799221 PMCID: PMC4370815 DOI: 10.1371/journal.pone.0119520] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 01/29/2015] [Indexed: 02/02/2023] Open
Abstract
Matrix 2 protein ectodomain (M2e) is considered a promising candidate for a broadly protective influenza vaccine. M2e-based vaccines against human influenza A provide only partial protection against avian influenza viruses because of differences in the M2e sequences. In this work, we evaluated the possibility of obtaining equal protection and immune response by using recombinant protein on the basis of flagellin as a carrier of the M2e peptides of human and avian influenza A viruses. Recombinant protein was generated by the fusion of two tandem copies of consensus M2e sequence from human influenza A and two copies of M2e from avian A/H5N1 viruses to flagellin (Flg-2M2eh2M2ek). Intranasal immunisation of Balb/c mice with recombinant protein significantly elicited anti-M2e IgG in serum, IgG and sIgA in BAL. Antibodies induced by the fusion protein Flg-2M2eh2M2ek bound efficiently to synthetic peptides corresponding to the human consensus M2e sequence as well as to the M2e sequence of A/Chicken/Kurgan/05/05 RG (H5N1) and recognised native M2e epitopes exposed on the surface of the MDCK cells infected with A/PR/8/34 (H1N1) and A/Chicken/Kurgan/05/05 RG (H5N1) to an equal degree. Immunisation led to both anti-M2e IgG1 and IgG2a response with IgG1 prevalence. We observed a significant intracellular production of IL-4, but not IFN-γ, by CD4+ T-cells in spleen of mice following immunisation with Flg-2M2eh2M2ek. Immunisation with the Flg-2M2eh2M2ek fusion protein provided similar protection from lethal challenge with human influenza A viruses (H1N1, H3N2) and avian influenza virus (H5N1). Immunised mice experienced significantly less weight loss and decreased lung viral titres compared to control mice. The data obtained show the potential for the development of an M2e-flagellin candidate influenza vaccine with broad spectrum protection against influenza A viruses of various origins.
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Affiliation(s)
- Liudmila A. Stepanova
- Department of Influenza Vaccines, Research Institute of Influenza, Ministry of Health of the Russian Federation, St. Petersburg, Russia
- * E-mail:
| | | | - Anna A. Kovaleva
- Department of Influenza Vaccines, Research Institute of Influenza, Ministry of Health of the Russian Federation, St. Petersburg, Russia
| | - Marina V. Potapchuk
- Department of Influenza Vaccines, Research Institute of Influenza, Ministry of Health of the Russian Federation, St. Petersburg, Russia
| | - Alexandr V. Korotkov
- Department of Influenza Vaccines, Research Institute of Influenza, Ministry of Health of the Russian Federation, St. Petersburg, Russia
| | - Mariia V. Sergeeva
- Department of Influenza Vaccines, Research Institute of Influenza, Ministry of Health of the Russian Federation, St. Petersburg, Russia
| | - Marina A. Kasianenko
- Department of Influenza Vaccines, Research Institute of Influenza, Ministry of Health of the Russian Federation, St. Petersburg, Russia
| | | | - Nikolai V. Ravin
- Centre “Bioengineering”, Russian Academy of Sciences, Moscow, Russia
- GenNanotech Ltd, St. Petersburg, Russia
| | - Liudmila M. Tsybalova
- Department of Influenza Vaccines, Research Institute of Influenza, Ministry of Health of the Russian Federation, St. Petersburg, Russia
| | | | - Oleg I. Kiselev
- Department of Influenza Vaccines, Research Institute of Influenza, Ministry of Health of the Russian Federation, St. Petersburg, Russia
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Abstract
This chapter reviews papers mostly written since 2005 that report results using live attenuated bacterial vectors to deliver after administration through mucosal surfaces, protective antigens, and DNA vaccines, encoding protective antigens to induce immune responses and/or protective immunity to pathogens that colonize on or invade through mucosal surfaces. Papers that report use of such vaccine vector systems for parenteral vaccination or to deal with nonmucosal pathogens or do not address induction of mucosal antibody and/or cellular immune responses are not reviewed.
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Sztein MB, Salerno-Goncalves R, McArthur MA. Complex adaptive immunity to enteric fevers in humans: lessons learned and the path forward. Front Immunol 2014; 5:516. [PMID: 25386175 PMCID: PMC4209864 DOI: 10.3389/fimmu.2014.00516] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 10/03/2014] [Indexed: 01/26/2023] Open
Abstract
Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever, and S. Paratyphi A and B, causative agents of paratyphoid fever, are major public health threats throughout the world. Although two licensed typhoid vaccines are currently available, they are only moderately protective and immunogenic necessitating the development of novel vaccines. A major obstacle in the development of improved typhoid, as well as paratyphoid vaccines is the lack of known immunological correlates of protection in humans. Considerable progress has been made in recent years in understanding the complex adaptive host responses against S. Typhi. Although the induction of S. Typhi-specific antibodies (including their functional properties) and memory B cells, as well as their cross-reactivity with S. Paratyphi A and S. Paratyphi B has been shown, the role of humoral immunity in protection remains undefined. Cell mediated immunity (CMI) is likely to play a dominant role in protection against enteric fever pathogens. Detailed measurements of CMI performed in volunteers immunized with attenuated strains of S. Typhi have shown, among others, the induction of lymphoproliferation, multifunctional type 1 cytokine production, and CD8(+) cytotoxic T-cell responses. In addition to systemic responses, the local microenvironment of the gut is likely to be of paramount importance in protection from these infections. In this review, we will critically assess current knowledge regarding the role of CMI and humoral immunity following natural S. Typhi and S. Paratyphi infections, experimental challenge, and immunization in humans. We will also address recent advances regarding cross-talk between the host's gut microbiota and immunization with attenuated S. Typhi, mechanisms of systemic immune responses, and the homing potential of S. Typhi-specific B- and T-cells to the gut and other tissues.
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Affiliation(s)
- Marcelo B Sztein
- Department of Pediatrics, Center for Vaccine Development (CVD), University of Maryland School of Medicine , Baltimore, MD , USA
| | - Rosangela Salerno-Goncalves
- Department of Pediatrics, Center for Vaccine Development (CVD), University of Maryland School of Medicine , Baltimore, MD , USA
| | - Monica A McArthur
- Department of Pediatrics, Center for Vaccine Development (CVD), University of Maryland School of Medicine , Baltimore, MD , USA
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Hiraizumi M, Tagawa Y. Isolation and characterization of flagellar filament from zoospores of Dermatophilus congolensis. Vet Microbiol 2014; 173:141-6. [PMID: 25132009 DOI: 10.1016/j.vetmic.2014.07.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 11/19/2022]
Abstract
Highly motile zoospores from Dermatophilus congolensis bovine isolates from clinical dermatophilosis in Japan were obtained by culturing at 27°C in an ambient atmosphere on heart infusion agar supplemented with 5% defibrinated sheep blood for 72h or in heart infusion broth for 48h with gentle shaking. After vigorous mechanical agitation of the zoospore suspension, the flagellar filaments detached from motile zoospores and were isolated in the clear gelatinous part of the final pellet by differential centrifugation. Typical morphology of a flagellar filament, with a width of approximately 15nm, was observed in the isolated flagellar filament by electron microscopy. A single major protein (flagellin) band with an apparent molecular mass of 35kDa was detected in the flagellar filament of D. congolensis strain AM-1 and that of 33kDa was detected in strain IT-2 by SDS-PAGE. In immunoblot analysis of whole-cell proteins from seven isolates of D. congolensis, antiserum to strain AM-1 zoospores reacted with the 35-kDa antigen band of strain AM-1, but not with any antigen band of other strains in a similar molecular mass range. In contrast, antiserum to strain IT-2 zoospores reacted with antigen bands at 33kDa from six strains, except strain AM-1. Similar strain-specific reactions of these anti-zoospore sera with isolated flagellar filaments from strains AM-1 and IT-2 were confirmed by immunoblot, indicating the presence of antigenic variations of flagellins of D. congolensis zoospores.
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Affiliation(s)
- Mieko Hiraizumi
- Aomori Prefectural Mutsu Livestock Hygiene Service Center, 2-18-15 Kanaya, Mutsu, Aomori 035-0072, Japan
| | - Yuichi Tagawa
- National Institute of Animal Health, NARO, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
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Teh CSJ, Chua KH, Thong KL. Paratyphoid fever: splicing the global analyses. Int J Med Sci 2014; 11:732-41. [PMID: 24904229 PMCID: PMC4045793 DOI: 10.7150/ijms.7768] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 03/05/2014] [Indexed: 11/24/2022] Open
Abstract
The incidence of enteric fever caused by Salmonella enterica serovar Paratyphi A (S. Paratyphi A) is increasing in many parts of the world. Although there is no major outbreak of paratyphoid fever in recent years, S. Paratyphi A infection still remains a public health problem in many tropical countries. Therefore, surveillance studies play an important role in monitoring infections and the emergence of multidrug resistance, especially in endemic countries such as India, Nepal, Pakistan and China. In China, enteric fever was caused predominantly by S. Paratyphi A rather than by Salmonella enterica serovar Typhi (S. Typhi). Sometimes, S. Paratyphi A infection can evolve into a carrier state which increases the risk of transmission for travellers. Hence, paratyphoid fever is usually classified as a "travel-associated" disease. To date, diagnosis of paratyphoid fever based on the clinical presentation is not satisfactory as it resembles other febrile illnesses, and could not be distinguished from S. Typhi infection. With the availability of Whole Genome Sequencing technology, the genomes of S. Paratyphi A could be studied in-depth and more specific targets for detection will be revealed. Hence, detection of S. Paratyphi A with Polymerase Chain Reaction (PCR) method appears to be a more reliable approach compared to the Widal test. On the other hand, due to increasing incidence of S. Paratyphi A infections worldwide, the need to produce a paratyphoid vaccine is essential and urgent. Hence various vaccine projects that involve clinical trials have been carried out. Overall, this review provides the insights of S. Paratyphi A, including the bacteriology, epidemiology, management and antibiotic susceptibility, diagnoses and vaccine development.
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Affiliation(s)
- Cindy Shuan Ju Teh
- 1. Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur
| | - Kek Heng Chua
- 2. Department of Biomedical Science, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur
| | - Kwai Lin Thong
- 3. Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur
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MacLennan CA, Martin LB, Micoli F. Vaccines against invasive Salmonella disease: current status and future directions. Hum Vaccin Immunother 2014; 10:1478-93. [PMID: 24804797 PMCID: PMC4185946 DOI: 10.4161/hv.29054] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Though primarily enteric pathogens, Salmonellae are responsible for a considerable yet under-appreciated global burden of invasive disease. In South and South-East Asia, this manifests as enteric fever caused by serovars Typhi and Paratyphi A. In sub-Saharan Africa, a similar disease burden results from invasive nontyphoidal Salmonellae, principally serovars Typhimurium and Enteritidis. The existing Ty21a live-attenuated and Vi capsular polysaccharide vaccines target S. Typhi and are not effective in young children where the burden of invasive Salmonella disease is highest. After years of lack of investment in new Salmonella vaccines, recent times have seen increased interest in the area led by emerging-market manufacturers, global health vaccine institutes and academic partners. New glycoconjugate vaccines against S. Typhi are becoming available with similar vaccines against other invasive serovars in development. With other new vaccines under investigation, including live-attenuated, protein-based and GMMA vaccines, now is an exciting time for the Salmonella vaccine field.
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Affiliation(s)
- Calman A MacLennan
- Novartis Vaccines Institute for Global Health; Siena, Italy; Medical Research Council Centre for Immune Regulation and Clinical Immunology Service; Institute of Biomedical Research, School of Immunity and Infection; College of Medicine and Dental Sciences; University of Birmingham; Birmingham, UK
| | - Laura B Martin
- Novartis Vaccines Institute for Global Health; Siena, Italy
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Vaccination with a single CD4 T cell peptide epitope from a Salmonella type III-secreted effector protein provides protection against lethal infection. Infect Immun 2014; 82:2424-33. [PMID: 24686055 DOI: 10.1128/iai.00052-14] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Salmonella infections affect millions worldwide and remain a significant cause of morbidity and mortality. It is known from mouse studies that CD4 T cells are essential mediators of immunity against Salmonella infection, yet it is not clear whether targeting CD4 T cell responses directly with peptide vaccines against Salmonella can be effective in combating infection. Additionally, it is not known whether T cell responses elicited against Salmonella secreted effector proteins can provide protective immunity against infection. In this study, we investigated both of these possibilities using prime-boost immunization of susceptible mice with a single CD4 T cell peptide epitope from Salmonella secreted effector protein I (SseI), a component of the Salmonella type III secretion system. This immunization conferred significant protection against lethal oral infection, equivalent to that conferred by whole heat-killed Salmonella bacteria. Surprisingly, a well-characterized T cell epitope from the flagellar protein FliC afforded no protection compared to immunization with an irrelevant control peptide. The protective response appeared to be most associated with polyfunctional CD4 T cells raised against the SseI peptide, since no antibodies were produced against any of the peptides and very little CD8 T cell response was observed. Overall, this study demonstrates that eliciting CD4 T cell responses against components of the Salmonella type III secretion system can contribute to protection against infection and should be considered in the design of future Salmonella subunit vaccines.
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Serum bactericidal assays to evaluate typhoidal and nontyphoidal Salmonella vaccines. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:712-21. [PMID: 24623629 DOI: 10.1128/cvi.00115-14] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Invasive Salmonella infections for which improved or new vaccines are being developed include enteric fever caused by Salmonella enterica serovars Typhi, Paratyphi A, and Paratyphi B and sepsis and meningitis in young children in sub-Saharan Africa caused by nontyphoidal Salmonella (NTS) serovars, particularly S. enterica serovars Typhimurium and Enteritidis. Assays are needed to measure functional antibodies elicited by the new vaccines to assess their immunogenicities and potential protective capacities. We developed in vitro assays to quantify serum bactericidal antibody (SBA) activity induced by S. Typhi, S. Paratyphi A, S. Typhimurium, and S. Enteritidis vaccines in preclinical studies. Complement from various sources was tested in assays designed to measure antibody-dependent complement-mediated killing. Serum from rabbits 3 to 4 weeks of age provided the best complement source compared to serum from pigs, goats, horses, bovine calves, or rabbits 8 to 12 weeks of age. For S. Enteritidis, S. Typhimurium, and S. Typhi SBA assays to be effective, bacteria had to be harvested at log phase. In contrast, S. Paratyphi A was equally susceptible to killing whether it was grown to the stationary or log phase. The typhoidal serovars were more susceptible to complement-mediated killing than were the nontyphoidal serovars. Lastly, the SBA endpoint titers correlated with serum IgG anti-lipopolysaccharide (LPS) titers in mice immunized with mucosally administered S. Typhimurium, S. Enteritidis, and S. Paratyphi A but not S. Typhi live attenuated vaccines. The SBA assay described here is a useful tool for measuring functional antibodies elicited by Salmonella vaccine candidates.
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Waddington CS, Darton TC, Pollard AJ. The challenge of enteric fever. J Infect 2014; 68 Suppl 1:S38-50. [DOI: 10.1016/j.jinf.2013.09.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2013] [Indexed: 11/27/2022]
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Tarahomjoo S. Utilizing bacterial flagellins against infectious diseases and cancers. Antonie van Leeuwenhoek 2013; 105:275-88. [PMID: 24276957 DOI: 10.1007/s10482-013-0075-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 11/12/2013] [Indexed: 12/31/2022]
Abstract
The flagellum is the organelle providing motility to bacterial cells and its activity is coupled to the cellular chemotaxis machinery. The flagellar filament is the largest portion of the flagellum, which consists of repeating subunits of the protein flagellin. Receptors of the innate immune system including Toll like receptor 5, ICE protease activating factor, and neuronal apoptosis inhibitory protein 5 signal in response to bacterial flagellins. In addition to inducing innate immune responses, bacterial flagellins mediate the development of adaptive immune responses to both flagellins and coadministered antigens. Therefore, these proteins have intensively been investigated for the vaccine development and the immunotherapy. This review describes the utilization of bacterial flagellins for the construction of vaccines against infectious diseases and cancer immunotherapy. Furthermore, the key factors affecting the performance of these systems are highlighted.
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Affiliation(s)
- Shirin Tarahomjoo
- Department of Biotechnology, Razi Vaccine and Serum Research Institute, 31975/148, Karaj, Iran,
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The role of the bacterial flagellum in adhesion and virulence. BIOLOGY 2013; 2:1242-67. [PMID: 24833223 PMCID: PMC4009794 DOI: 10.3390/biology2041242] [Citation(s) in RCA: 326] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/27/2013] [Accepted: 09/30/2013] [Indexed: 12/11/2022]
Abstract
The bacterial flagellum is a complex apparatus assembled of more than 20 different proteins. The flagellar basal body traverses the cell wall, whereas the curved hook connects the basal body to the whip-like flagellar filament that protrudes several µm from the bacterial cell. The flagellum has traditionally been regarded only as a motility organelle, but more recently it has become evident that flagella have a number of other biological functions. The major subunit, flagellin or FliC, of the flagellum plays a well-documented role in innate immunity and as a dominant antigen of the adaptive immune response. Importantly, flagella have also been reported to function as adhesins. Whole flagella have been indicated as significant in bacterial adhesion to and invasion into host cells. In various pathogens, e.g., Escherichia coli, Pseudomonas aeruginosa and Clostridium difficile, flagellin and/or the distally located flagellar cap protein have been reported to function as adhesins. Recently, FliC of Shiga-toxigenic E. coli was shown to be involved in cellular invasion via lipid rafts. Here, we examine the latest or most important findings regarding flagellar adhesive and invasive properties, especially focusing on the flagellum as a potential virulence factor.
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Abstract
PURPOSE OF REVIEW Strains of Salmonella enterica subsp. enterica are amongst the most commonly identified invasive bacterial pathogens in resource-poor settings, and cause significant mortality, particularly in children. In this study we review recent progress in the development of vaccines against S. Typhi, S. Paratyphi and nontyphoidal Salmonella for children. RECENT FINDINGS Typhoid remains common and S. Paratyphi A is increasingly recognized as a cause of enteric fever in Asia. In rural Africa, nontyphoidal salmonellae are among the most common invasive bacterial infections, although S. Typhi predominates in some urban centres. Licensed vaccines against typhoid have moderate but useful efficacy but neither of the two available vaccines can be used in infants. Although Ty21a may afford some cross-protection against S. Paratyphi B, there are no vaccines that specifically target paratyphoid or any nontyphoidal Salmonella. Several live attenuated vaccines are under development and may offer some advantages over Ty21a. Vi-conjugate vaccines should offer children excellent protection from typhoid once licensed. SUMMARY There are few effective vaccines against Salmonella sp. and those that do exist target only one serovar, S. Typhi. Research is urgently needed to combat emerging agents of enteric fever such as S. Paratyphi A as well as nontyphoidal serovars, which commonly cause invasive disease in Africa.
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Highly specific and cost-efficient detection of Salmonella Paratyphi A combining aptamers with single-walled carbon nanotubes. SENSORS 2013; 13:6865-81. [PMID: 23698275 PMCID: PMC3690085 DOI: 10.3390/s130506865] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 04/22/2013] [Accepted: 05/17/2013] [Indexed: 01/20/2023]
Abstract
In this paper, a panel of single-stranded DNA aptamers with high affinity and specificity against Salmonella Paratyphi A was selected from an enriched oligonucleotide pool by a whole-cell-Systematic Evolution of Ligands by Exponential Enrichment (SELEX) procedure, during which four other Salmonella serovars were used as counter-selection targets. It was determined through a fluorescence assay that the selected aptamers had high binding ability and specificity to this pathogen. The dissociation constant of these aptamers were up to nanomolar range, and aptamer Apt22 with the lowest Kd (47 ± 3 nM) was used in cell imaging experiments. To detect this bacteria with high specificity and cost-efficiently, a novel useful detection method was also constructed based on the noncovalent self-assembly of single-walled carbon nanotubes (SWNTs) and DNAzyme-labeled aptamer detection probes. The amounts of target bacteria could be quantified by exploiting chemoluminescence intensity changes at 420 nm and the detection limit of the method was 103 cfu/mL. This study demonstrated the applicability of Salmonella specific aptamers and their potential for use in the detection of Salmonella in food, clinical and environmental samples.
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Micoli F, Rondini S, Gavini M, Pisoni I, Lanzilao L, Colucci AM, Giannelli C, Pippi F, Sollai L, Pinto V, Berti F, MacLennan CA, Martin LB, Saul A. A scalable method for O-antigen purification applied to various Salmonella serovars. Anal Biochem 2013; 434:136-45. [PMID: 23142430 PMCID: PMC3967520 DOI: 10.1016/j.ab.2012.10.038] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 10/25/2012] [Accepted: 10/26/2012] [Indexed: 11/18/2022]
Abstract
The surface lipopolysaccharide of gram-negative bacteria is both a virulence factor and a B cell antigen. Antibodies against O-antigen of lipopolysaccharide may confer protection against infection, and O-antigen conjugates have been designed against multiple pathogens. Here, we describe a simplified methodology for extraction and purification of the O-antigen core portion of Salmonella lipopolysaccharide, suitable for large-scale production. Lipopolysaccharide extraction and delipidation are performed by acetic acid hydrolysis of whole bacterial culture and can take place directly in a bioreactor, without previous isolation and inactivation of bacteria. Further O-antigen core purification consists of rapid filtration and precipitation steps, without using enzymes or hazardous chemicals. The process was successfully applied to various Salmonella enterica serovars (Paratyphi A, Typhimurium, and Enteritidis), obtaining good yields of high-quality material, suitable for conjugate vaccine preparations.
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Affiliation(s)
- F Micoli
- Novartis Vaccines Institute for Global Health, 53100 Siena, Italy.
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Abstract
PURPOSE OF REVIEW This review summarizes the recent advances in vaccination against Salmonella enterica serovar Typhi and highlights the data supporting the development of next generation vaccines to address paratyphoid fever and invasive nontyphoidal Salmonella (iNTS) disease. RECENT FINDINGS There has been increasing awareness of the disease burden caused by S. Typhi particularly in Africa and greater recognition of S. Paratyphi A's contribution to enteric fever episodes throughout Asia. Groups have been working to improve the existing typhoid vaccines and provide comprehensive data on the feasibility of their implementation in endemic settings. These data have resulted in modifications to the recommendations for typhoid vaccination in traveller markets and endemic settings, and has also led to the development of S. Paratyphi A vaccine components that can be combined with existing typhoid vaccines to generate bivalent formulations against enteric fever. The epidemiology of iNTS serovars as cause of appreciable morbidity and mortality in Africa, and the need for vaccines, has also become more widely appreciated. SUMMARY Current typhoid vaccines, although moderately effective for short periods of time, cannot be used in all age groups and only target one of the clinically relevant Salmonella serovars. Greater effort must be placed on the development and implementation of improved vaccines for the disease burden resulting from Typhi, Paratyphi A or iNTS infections.
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Micoli F, Rondini S, Gavini M, Lanzilao L, Medaglini D, Saul A, Martin LB. O:2-CRM(197) conjugates against Salmonella Paratyphi A. PLoS One 2012; 7:e47039. [PMID: 23144798 PMCID: PMC3492368 DOI: 10.1371/journal.pone.0047039] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 09/07/2012] [Indexed: 11/18/2022] Open
Abstract
Enteric fevers remain a common and serious disease, affecting mainly children and adolescents in developing countries. Salmonella enterica serovar Typhi was believed to cause most enteric fever episodes, but several recent reports have shown an increasing incidence of S. Paratyphi A, encouraging the development of a bivalent vaccine to protect against both serovars, especially considering that at present there is no vaccine against S. Paratyphi A. The O-specific polysaccharide (O:2) of S. Paratyphi A is a protective antigen and clinical data have previously demonstrated the potential of using O:2 conjugate vaccines. Here we describe a new conjugation chemistry to link O:2 and the carrier protein CRM(197), using the terminus 3-deoxy-D-manno-octulosonic acid (KDO), thus leaving the O:2 chain unmodified. The new conjugates were tested in mice and compared with other O:2-antigen conjugates, synthesized adopting previously described methods that use CRM(197) as carrier protein. The newly developed conjugation chemistry yielded immunogenic conjugates with strong serum bactericidal activity against S. Paratyphi A.
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Goh YS, MacLennan CA. Invasive African nontyphoidal Salmonella requires high levels of complement for cell-free antibody-dependent killing. J Immunol Methods 2012; 387:121-9. [PMID: 23085530 DOI: 10.1016/j.jim.2012.10.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2012] [Revised: 10/09/2012] [Accepted: 10/11/2012] [Indexed: 11/18/2022]
Abstract
Nontyphoidal isolates of Salmonella (NTS), particularly Salmonella Typhimurium, are a major cause of invasive bacteremia in Africa. Despite this, no vaccine against NTS is currently available for use in humans. If a NTS vaccine is to be developed in a timely manner, there is a need to develop assays to assess its in vivo efficacy. Assessment of potential efficacy of candidate vaccines in preclinical models is important for proof-of-concept and reduces attrition of vaccines in clinical trials. Serum bactericidal assays (SBA) are often used to assess the functional activity of vaccine-induced antibody responses targeted against Gram-negative bacteria with results given as the maximum dilution of serum that can effect bacterial killing. Previously we have found evidence for a protective role for antibody-induced complement-mediated killing of NTS in African children using an undiluted whole serum SBA. However, endogenous complement in diluted human sera is limiting and insufficient to effect bactericidal activity against S. Typhimurium beyond two two-fold dilutions. In the current study, we examined the requirements for SBA against NTS using baby rabbit serum (BRS) as an exogenous source of complement. We found that the amount of complement required for antibody-mediated bactericidal activity is much higher for the invasive African S. Typhimurium isolate D23580, compared with the laboratory S. Typhimurium LT2 and Salmonella Paratyphi A CVD1901. While 20% BRS was sufficient to kill LT2 and CVD1901, 75% BRS was needed to kill D23580. Our findings demonstrate that one concentration of exogenous complement is not suitable for SBA against all Salmonella isolates. To develop SBA to assess the in vivo efficacy of Salmonella vaccines, it is necessary to optimize the assay for the Salmonella isolates against which the vaccine is targeted.
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Affiliation(s)
- Yun Shan Goh
- Novartis Vaccines Institute for Global Health, Via Fiorentina 1, 53100 Siena, Italy
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Live oral typhoid vaccine Ty21a induces cross-reactive humoral immune responses against Salmonella enterica serovar Paratyphi A and S. Paratyphi B in humans. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 19:825-34. [PMID: 22492745 DOI: 10.1128/cvi.00058-12] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Enteric fever caused by Salmonella enterica serovar Paratyphi A infection has emerged as an important public health problem. Recognizing that in randomized controlled field trials oral immunization with attenuated S. enterica serovar Typhi live vaccine Ty21a conferred significant cross-protection against S. Paratyphi B but not S. Paratyphi A disease, we undertook a clinical study to ascertain whether humoral immune responses could explain the field trial results. Ty21a immunization of adult residents of Maryland elicited predominantly IgA antibody-secreting cells (ASC) that recognize S. Typhi lipopolysaccharide (LPS). Cross-reactivity to S. Paratyphi A LPS was significantly lower than that to S. Paratyphi B LPS. ASC producing IgG and IgA that bind LPS from each of these Salmonella serovars expressed CD27 and integrin α4β7 (gut homing), with a significant proportion coexpressing CD62L (secondary lymphoid tissue homing). No significant differences were observed in serum antibody against LPS of the different serovars. Levels of IgA B memory (B(M)) cells to S. Typhi LPS were significantly higher than those against S. Paratyphi A or B LPS, with no differences observed between S. Paratyphi A and B. The response of IgA B(M) to outer membrane proteins (OMP) from S. Typhi was significantly stronger than that to OMP of S. Paratyphi A but similar to that to OMP of S. Paratyphi B. The percentages of IgG or IgA B(M) responders to LPS or OMP from these Salmonella strains were similar. Whereas cross-reactive humoral immune responses to S. Paratyphi A or B antigens are demonstrable following Ty21a immunization, they cannot explain the efficacy data gleaned from controlled field trials.
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