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Lu T, Das S, Howlader DR, Picking WD, Picking WL. Shigella Vaccines: The Continuing Unmet Challenge. Int J Mol Sci 2024; 25:4329. [PMID: 38673913 PMCID: PMC11050647 DOI: 10.3390/ijms25084329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 04/09/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Shigellosis is a severe gastrointestinal disease that annually affects approximately 270 million individuals globally. It has particularly high morbidity and mortality in low-income regions; however, it is not confined to these regions and occurs in high-income nations when conditions allow. The ill effects of shigellosis are at their highest in children ages 2 to 5, with survivors often exhibiting impaired growth due to infection-induced malnutrition. The escalating threat of antibiotic resistance further amplifies shigellosis as a serious public health concern. This review explores Shigella pathology, with a primary focus on the status of Shigella vaccine candidates. These candidates include killed whole-cells, live attenuated organisms, LPS-based, and subunit vaccines. The strengths and weaknesses of each vaccination strategy are considered. The discussion includes potential Shigella immunogens, such as LPS, conserved T3SS proteins, outer membrane proteins, diverse animal models used in Shigella vaccine research, and innovative vaccine development approaches. Additionally, this review addresses ongoing challenges that necessitate action toward advancing effective Shigella prevention and control measures.
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Affiliation(s)
- Ti Lu
- Department of Veterinary Pathobiology and Bond Life Science Center, University of Missouri, Columbia, MO 65201, USA; (D.R.H.); (W.D.P.)
| | - Sayan Das
- Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201, USA;
| | - Debaki R. Howlader
- Department of Veterinary Pathobiology and Bond Life Science Center, University of Missouri, Columbia, MO 65201, USA; (D.R.H.); (W.D.P.)
| | - William D. Picking
- Department of Veterinary Pathobiology and Bond Life Science Center, University of Missouri, Columbia, MO 65201, USA; (D.R.H.); (W.D.P.)
| | - Wendy L. Picking
- Department of Veterinary Pathobiology and Bond Life Science Center, University of Missouri, Columbia, MO 65201, USA; (D.R.H.); (W.D.P.)
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Hossain MJ, Svennerholm AM, Carlin N, D’Alessandro U, Wierzba TF. A Perspective on the Strategy for Advancing ETVAX ®, An Anti-ETEC Diarrheal Disease Vaccine, into a Field Efficacy Trial in Gambian Children: Rationale, Challenges, Lessons Learned, and Future Directions. Microorganisms 2023; 12:90. [PMID: 38257916 PMCID: PMC10819518 DOI: 10.3390/microorganisms12010090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/22/2023] [Accepted: 12/23/2023] [Indexed: 01/24/2024] Open
Abstract
For the first time in over 20 years, an Enterotoxigenic Escherichia coli (ETEC) vaccine candidate, ETVAX®, has advanced into a phase 2b field efficacy trial for children 6-18 months of age in a low-income country. ETVAX® is an inactivated whole cell vaccine that has gone through a series of clinical trials to provide a rationale for the design elements of the Phase 2b trial. This trial is now underway in The Gambia and will be a precursor to an upcoming pivotal phase 3 trial. To reach this point, numerous findings were brought together to define factors such as safe and immunogenic doses for children, and the possible benefit of a mucosal adjuvant, double mutant labile toxin (dmLT). Considering the promising but still underexplored potential of inactivated whole cells in oral vaccination, we present a perspective compiling key observations from past ETVAX® trials that informed The Gambian trial design. This report will update the trial's status and explore future directions for ETEC vaccine trials. Our aim is to provide not only an update on the most advanced ETEC vaccine candidate but also to offer insights beneficial for the development of other much-needed oral whole-cell vaccines against enteric and other pathogens.
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Affiliation(s)
- M. Jahangir Hossain
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, Banjul P.O. Box 273, The Gambia
| | - Ann-Mari Svennerholm
- Department of Microbiology and Immunology, Gothenburg University Research Institute (GUVAX), Gothenburg University, 40530 Gothenburg, Sweden
| | - Nils Carlin
- Scandinavian Biopharma, Industrivägen 1, 17148 Solna, Sweden
| | - Umberto D’Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, Banjul P.O. Box 273, The Gambia
| | - Thomas F. Wierzba
- Section on Infectious Diseases, Department of Internal Medicine, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
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Shahnaij M, Amin MB, Hoque MM, Mondol AS, Rana KJ, Azmi IJ, Talukder KA. Characterization of Shigella flexneri Serotype 6 Strains Isolated from Bangladesh and Identification of a New Phylogenetic Cluster. J Bacteriol 2023; 205:e0040622. [PMID: 36927058 PMCID: PMC10127597 DOI: 10.1128/jb.00406-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 02/16/2023] [Indexed: 03/18/2023] Open
Abstract
A significant cause of shigellosis in Bangladesh and other developing countries is Shigella flexneri serotype 6. This serotype has been subtyped, on the basis of the absence or presence of a group-specific antigen, E1037, into S. flexneri 6a and 6b, respectively. Here, we provided rationales for the subclassification, using several phenotypic and molecular tools. A set of S. flexneri 6a and 6b strains isolated between 1997 and 2015 were characterized by analyzing their biochemical properties, plasmid profiles, virulence markers, pulsed-field gel electrophoresis (PFGE) results, and ribotype. Additionally, the genomic relatedness of these subserotypes was investigated with global isolates of serotype 6 using publicly available genomes. Both subserotypes of S. flexneri 6 agglutinated with monoclonal antiserum against S. flexneri (MASF) B and type VI-specific antiserum (MASF VI) and were PCR positive for O-antigen flippase-specific genes and virulence markers (ipaH, ial, sen, and sigA). Unlike S. flexneri 6a strains, S. flexneri 6b strains seroagglutinated with anti-E1037 antibodies, MASF IV-I. Notably, these two antigenically distinct subserotypes were clonally diverse, showing two distinct PFGE patterns following the digestion of chromosomal DNA with either XbaI or IceuI. In addition, hybridization of a 16S rRNA gene probe with HindIII-digested genomic DNA yielded two distinguishing ribotypes. Genomic comparison of S. flexneri subserotype 6a and 6b strains from Bangladesh indicated that, although these strains were in genomic synteny, the majority of them formed a unique phylogroup (PG-4) that was missing for the global isolates. This study supports the subserotyping and emphasizes the need for global monitoring of the S. flexneri subserotypes 6a and 6b. IMPORTANCE Shigella flexneri serotype 6 is one of the predominant serotypes among shigellosis cases in Bangladesh. Characterization of a novel subserotype of S. flexneri 6 (VI:E1037), agglutinated with type 6-specific antibody and anti-E1037, indicates a unique evolutionary ancestry. PFGE genotyping supports the finding that these two antigenically distinct subserotypes are clonally diverse. A phylogenetic study based on single-nucleotide polymorphism (SNP) data revealed that these two subserotypes were in genomic synteny, although their genomes were reduced. Interestingly, a majority of the S. flexneri 6 strains isolated from Bangladesh form a novel phylogenetic cluster. Therefore, this report underpins the global monitoring and tracking of the novel subserotype.
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Affiliation(s)
- Mohammad Shahnaij
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Mohammed Badrul Amin
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - M. Mozammel Hoque
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Abdus Salam Mondol
- Department of Public Health Nutrition, Primeasia University, Dhaka, Bangladesh
| | - Kazi Jewel Rana
- Department of Biochemistry and Molecular Biology, University of Dhaka, Dhaka, Bangladesh
| | - Ishrat J. Azmi
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
| | - Kaisar A. Talukder
- Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh
- Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Santosh, Bangladesh
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Toward a Shigella Vaccine: Opportunities and Challenges to Fight an Antimicrobial-Resistant Pathogen. Int J Mol Sci 2023; 24:ijms24054649. [PMID: 36902092 PMCID: PMC10003550 DOI: 10.3390/ijms24054649] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/04/2023] Open
Abstract
Shigellosis causes more than 200,000 deaths worldwide and most of this burden falls on Low- and Middle-Income Countries (LMICs), with a particular incidence in children under 5 years of age. In the last decades, Shigella has become even more worrisome because of the onset of antimicrobial-resistant strains (AMR). Indeed, the WHO has listed Shigella as one of the priority pathogens for the development of new interventions. To date, there are no broadly available vaccines against shigellosis, but several candidates are being evaluated in preclinical and clinical studies, bringing to light very important data and information. With the aim to facilitate the understanding of the state-of-the-art of Shigella vaccine development, here we report what is known about Shigella epidemiology and pathogenesis with a focus on virulence factors and potential antigens for vaccine development. We discuss immunity after natural infection and immunization. In addition, we highlight the main characteristics of the different technologies that have been applied for the development of a vaccine with broad protection against Shigella.
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Pokharel P, Dhakal S, Dozois CM. The Diversity of Escherichia coli Pathotypes and Vaccination Strategies against This Versatile Bacterial Pathogen. Microorganisms 2023; 11:344. [PMID: 36838308 PMCID: PMC9965155 DOI: 10.3390/microorganisms11020344] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 01/24/2023] [Accepted: 01/25/2023] [Indexed: 02/03/2023] Open
Abstract
Escherichia coli (E. coli) is a gram-negative bacillus and resident of the normal intestinal microbiota. However, some E. coli strains can cause diseases in humans, other mammals and birds ranging from intestinal infections, for example, diarrhea and dysentery, to extraintestinal infections, such as urinary tract infections, respiratory tract infections, meningitis, and sepsis. In terms of morbidity and mortality, pathogenic E. coli has a great impact on public health, with an economic cost of several billion dollars annually worldwide. Antibiotics are not usually used as first-line treatment for diarrheal illness caused by E. coli and in the case of bloody diarrhea, antibiotics are avoided due to the increased risk of hemolytic uremic syndrome. On the other hand, extraintestinal infections are treated with various antibiotics depending on the site of infection and susceptibility testing. Several alarming papers concerning the rising antibiotic resistance rates in E. coli strains have been published. The silent pandemic of multidrug-resistant bacteria including pathogenic E. coli that have become more difficult to treat favored prophylactic approaches such as E. coli vaccines. This review provides an overview of the pathogenesis of different pathotypes of E. coli, the virulence factors involved and updates on the major aspects of vaccine development against different E. coli pathotypes.
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Affiliation(s)
- Pravil Pokharel
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), 531 Boul des Prairies, Laval, QC H7V 1B7, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Sabin Dhakal
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), 531 Boul des Prairies, Laval, QC H7V 1B7, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Charles M. Dozois
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), 531 Boul des Prairies, Laval, QC H7V 1B7, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, Saint-Hyacinthe, QC J2S 2M2, Canada
- Pasteur Network, Laval, QC H7V 1B7, Canada
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6
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Walker RI, Bourgeois AL. Oral inactivated whole cell vaccine for mucosal immunization: ETVAX case study. Front Immunol 2023; 14:1125102. [PMID: 36936951 PMCID: PMC10018008 DOI: 10.3389/fimmu.2023.1125102] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 02/03/2023] [Indexed: 03/06/2023] Open
Abstract
Oral immunization is an effective strategy for inducing protective immunity against mucosal enteric pathogens. Although live-attenuated as well as subunit approaches have been explored for vaccination against enteric pathogens, inactivated whole bacterial cells may also be effective in introducing protective immunity. Successfully accomplishing this goal with inactivated whole bacterial cells will require that a complex antigenic repertoire be presented in controlled immunogenic amounts, in a safe and relatively simple and self-contained delivery format. The benefit from immunization with whole cell vaccines can be further enhanced through genetic engineering to over-express selected antigens and also by the use of mucosal adjuvants to direct a more robust immunologic response. These steps are being taken for the development of ETVAX, the most clinically advanced vaccine candidate against the major enteric pathogen, enterotoxigenic Escherichia coli (ETEC) with significant positive impact.
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Huan YW, Fa-Arun J, Wang B. The Role of O-antigen in P1 Transduction of Shigella flexneri and Escherichia coli with its Alternative S' Tail Fibre. J Mol Biol 2022; 434:167829. [PMID: 36116540 DOI: 10.1016/j.jmb.2022.167829] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 09/03/2022] [Accepted: 09/12/2022] [Indexed: 11/30/2022]
Abstract
Enterobacteria phage P1 expresses two types of tail fibre, S and S'. Despite the wide usage of phage P1 for transduction, the host range and the receptor for its alternative S' tail fibre was never determined. Here, a ΔS-cin Δpac E. coli P1 lysogenic strain was generated to allow packaging of phagemid DNA into P1 phage having either S or S' tail fibre. P1(S') could transduce phagemid DNA into Shigella flexneri 2a 2457O, Shigella flexneri 5a M90T and Escherichia coli O3 efficiently. Mutational analysis of the O-antigen assembly genes and LPS inhibition assays indicated that P1(S') transduction requires at least one O-antigen unit. E. coli O111:B4 LPS produced a high neutralising effect against P1(S') transduction, indicating that this E. coli strain could be susceptible to P1(S')-mediated transduction. Mutations in the O-antigen modification genes of S. flexneri 2a 2457O and S. flexneri 5a M90T did not cause significant changes to P1(S') transduction efficiency. A higher transduction efficiency of P1(S') improved the delivery of a cas9 antimicrobial phagemid into both S. flexneri 2457O and M90T. These findings provide novel insights into P1 tropism-switching, by identifying the bacterial strains which are susceptible to P1(S')-mediated transduction, as well as demonstrating its potential for delivering a DNA sequence-specific Cas9 antimicrobial into clinically relevant S. flexneri.
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Affiliation(s)
- Yang W Huan
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, United Kingdom
| | - Jidapha Fa-Arun
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FF, United Kingdom
| | - Baojun Wang
- College of Chemical and Biological Engineering & ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310058, China; Research Centre of Biological Computation, Zhejiang Laboratory, Hangzhou 311100, China.
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Choy RKM, Bourgeois AL, Ockenhouse CF, Walker RI, Sheets RL, Flores J. Controlled Human Infection Models To Accelerate Vaccine Development. Clin Microbiol Rev 2022; 35:e0000821. [PMID: 35862754 PMCID: PMC9491212 DOI: 10.1128/cmr.00008-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The timelines for developing vaccines against infectious diseases are lengthy, and often vaccines that reach the stage of large phase 3 field trials fail to provide the desired level of protective efficacy. The application of controlled human challenge models of infection and disease at the appropriate stages of development could accelerate development of candidate vaccines and, in fact, has done so successfully in some limited cases. Human challenge models could potentially be used to gather critical information on pathogenesis, inform strain selection for vaccines, explore cross-protective immunity, identify immune correlates of protection and mechanisms of protection induced by infection or evoked by candidate vaccines, guide decisions on appropriate trial endpoints, and evaluate vaccine efficacy. We prepared this report to motivate fellow scientists to exploit the potential capacity of controlled human challenge experiments to advance vaccine development. In this review, we considered available challenge models for 17 infectious diseases in the context of the public health importance of each disease, the diversity and pathogenesis of the causative organisms, the vaccine candidates under development, and each model's capacity to evaluate them and identify correlates of protective immunity. Our broad assessment indicated that human challenge models have not yet reached their full potential to support the development of vaccines against infectious diseases. On the basis of our review, however, we believe that describing an ideal challenge model is possible, as is further developing existing and future challenge models.
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Affiliation(s)
- Robert K. M. Choy
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | - A. Louis Bourgeois
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | | | - Richard I. Walker
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | | | - Jorge Flores
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
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Nothaft H, Bian X, Shajahan A, Miller WG, Bolick DT, Guerrant RL, Azadi P, Ng KKS, Szymanski CM. Detecting Glucose Fluctuations in the Campylobacter jejuni N-Glycan Structure. ACS Chem Biol 2021; 16:2690-2701. [PMID: 34726367 DOI: 10.1021/acschembio.1c00498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Campylobacter jejuni is a significant cause of human gastroenteritis worldwide, and all strains express an N-glycan that is added to at least 80 different proteins. We characterized 98 C. jejuni isolates from infants from 7 low- and middle-income countries and identified 4 isolates unreactive with our N-glycan-specific antiserum that was raised against the C. jejuni heptasaccharide composed of GalNAc-GalNAc-GalNAc(Glc)-GalNAc-GalNAc-diNAcBac. Mass spectrometric analyses indicated these isolates express a hexasaccharide lacking the glucose branch. Although all 4 strains encode the PglI glucosyltransferase (GlcTF), one aspartate in the DXDD motif was missing, an alteration also present in ∼4% of all available PglI sequences. Deleting this residue from an active PglI resulted in a nonfunctional GlcTF when the protein glycosylation system was reconstituted in E. coli, while replacement with Glu/Ala was not deleterious. Molecular modeling proposed a mechanism for how the DXDD residues and the structure/length beyond the motif influence activity. Mouse vaccination with an E. coli strain expressing the full-length heptasaccharide produced N-glycan-specific antibodies and a corresponding reduction in Campylobacter colonization and weight loss following challenge. However, the antibodies did not recognize the hexasaccharide and were unable to opsonize C. jejuni isolates lacking glucose, suggesting this should be considered when designing N-glycan-based vaccines to prevent campylobacteriosis.
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Affiliation(s)
- Harald Nothaft
- Department of Medical Microbiology and Immunology, University of Alberta, Katz Group Centre, Edmonton, Alberta T6G 2E9, Canada
| | - Xiaoming Bian
- Department of Microbiology, University of Georgia, 527 Biological Sciences Building, Athens, Georgia 30602, United States
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
| | - Asif Shajahan
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
| | - William G. Miller
- Produce Safety and Microbiology Research Unit, Agricultural Research Service, United States Department of Agriculture, 800 Buchanan Street, Albany, California 94710, United States
| | - David T. Bolick
- Center for Global Health Equity, Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States
| | - Richard L. Guerrant
- Center for Global Health Equity, Division of Infectious Diseases and International Health, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
| | - Kenneth K. S. Ng
- Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada
| | - Christine M. Szymanski
- Department of Medical Microbiology and Immunology, University of Alberta, Katz Group Centre, Edmonton, Alberta T6G 2E9, Canada
- Department of Microbiology, University of Georgia, 527 Biological Sciences Building, Athens, Georgia 30602, United States
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, United States
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Recent Progress in Shigella and Burkholderia pseudomallei Vaccines. Pathogens 2021; 10:pathogens10111353. [PMID: 34832508 PMCID: PMC8621228 DOI: 10.3390/pathogens10111353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 12/28/2022] Open
Abstract
Significant advancement has been made in the development of vaccines against bacterial pathogens. However, several roadblocks have been found during the evaluation of vaccines against intracellular bacterial pathogens. Therefore, new lessons could be learned from different vaccines developed against unrelated intracellular pathogens. Bacillary dysentery and melioidosis are important causes of morbidity and mortality in developing nations, which are caused by the intracellular bacteria Shigella and Burkholderia pseudomallei, respectively. Although the mechanisms of bacterial infection, dissemination, and route of infection do not provide clues about the commonalities of the pathogenic infectious processes of these bacteria, a wide variety of vaccine platforms recently evaluated suggest that in addition to the stimulation of antibodies, identifying protective antigens and inducing T cell responses are some additional required elements to induce effective protection. In this review, we perform a comparative evaluation of recent candidate vaccines used to combat these two infectious agents, emphasizing the common strategies that can help investigators advance effective and protective vaccines to clinical trials.
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Citiulo F, Necchi F, Mancini F, Rossi O, Aruta MG, Gasperini G, Alfini R, Rondini S, Micoli F, Rappuoli R, Saul A, Martin LB. Rationalizing the design of a broad coverage Shigella vaccine based on evaluation of immunological cross-reactivity among S. flexneri serotypes. PLoS Negl Trop Dis 2021; 15:e0009826. [PMID: 34644291 PMCID: PMC8589205 DOI: 10.1371/journal.pntd.0009826] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 11/12/2021] [Accepted: 09/21/2021] [Indexed: 11/21/2022] Open
Abstract
No vaccine to protect against an estimated 238,000 shigellosis deaths per year is widely available. S. sonnei is the most prevalent Shigella, and multiple serotypes of S. flexneri, which change regionally and globally, also cause significant disease. The leading Shigella vaccine strategies are based on the delivery of serotype specific O-antigens. A strategy to minimize the complexity of a broadly-protective Shigella vaccine is to combine components from S. sonnei with S. flexneri serotypes that induce antibodies with maximum cross-reactivity between different serotypes. We used the GMMA-technology to immunize animal models and generate antisera against 14 S. flexneri subtypes from 8 different serotypes that were tested for binding to and bactericidal activity against a panel of 11 S. flexneri bacteria lines. Some immunogens induced broadly cross-reactive antibodies that interacted with most of the S. flexneri in the panel, while others induced antibodies with narrower specificity. Most cross-reactivity could not be assigned to modifications of the O-antigen, by glucose, acetate or phosphoethanolamine, common to several of the S. flexneri serotypes. This allowed us to revisit the current dogma of cross-reactivity among S. flexneri serotypes suggesting that a broadly protective vaccine is feasible with limited number of appropriately selected components. Thus, we rationally designed a 4-component vaccine selecting GMMA from S. sonnei and S. flexneri 1b, 2a and 3a. The resulting formulation was broadly cross-reactive in mice and rabbits, inducing antibodies that killed all S. flexneri serotypes tested. This study provides the framework for a broadly-protective Shigella vaccine which needs to be verified in human trials. A strategy to optimize the composition for a broadly-protective Shigella vaccine is to combine components directed against S. sonnei with S. flexneri serotypes to induce antibody responses with the maximum cross-reactivity between different serotypes. Based on mouse and rabbit immunogenicity, we selected 4 GMMA-immunogens, derived from S. sonnei and S. flexneri 1b, 2a and 3a, able to induce antibodies that were broadly bactericidal against most epidemiologically significant S. flexneri strains in mice and rabbits. This was not predicted on the basis of O-antigen modifications conferring serotype or group specificities and allowed revisiting the dogma of cross-protection among S. flexneri serotypes. Overall, this study provides a framework for the rational design of a broadly-protective vaccine that will be evaluated in upcoming human vaccine trials. It also tackles a key issue regarding Shigella vaccine development that is balancing a sufficient number of antigenic components in the vaccine to provide adequate coverage of serotype diversity while minimizing complexity.
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Affiliation(s)
- Francesco Citiulo
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
- * E-mail:
| | - Francesca Necchi
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | - Francesca Mancini
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | - Omar Rossi
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | | | | | - Renzo Alfini
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | | | - Francesca Micoli
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | | | - Allan Saul
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
| | - Laura B. Martin
- GSK Vaccines Institute for Global Health S.r.l. (GVGH), Siena, Italy
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Thorsing M, Krogh TJ, Vitved L, Nawrocki A, Jakobsen R, Larsen MR, Chakraborty S, Bourgeois AL, Andersen AZ, Boysen A. Linking inherent O-Linked Protein Glycosylation of YghJ to Increased Antigen Potential. Front Cell Infect Microbiol 2021; 11:705468. [PMID: 34490144 PMCID: PMC8417355 DOI: 10.3389/fcimb.2021.705468] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/23/2021] [Indexed: 11/13/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a WHO priority pathogen and vaccine target which causes infections in low-income and middle-income countries, travelers visiting endemic regions. The global urgent demand for an effective preventive intervention has become more pressing as ETEC strains have become increasingly multiple antibiotic resistant. However, the vaccine development pipeline has been slow to address this urgent need. To date, vaccine development has focused mainly on canonical antigens such as colonization factors and expressed toxins but due to genomic plasticity of this enteric pathogen, it has proven difficult to develop effective vaccines. In this study, we investigated the highly conserved non-canonical vaccine candidate YghJ/SsLE. Using the mass spectrometry-based method BEMAP, we demonstrate that YghJ is hyperglycosylated in ETEC and identify 54 O-linked Set/Thr residues within the 1519 amino acid primary sequence. The glycosylation sites are evenly distributed throughout the sequence and do not appear to affect the folding of the overall protein structure. Although the glycosylation sites only constitute a minor subpopulation of the available epitopes, we observed a notable difference in the immunogenicity of the glycosylated YghJ and the non-glycosylated protein variant. We can demonstrate by ELISA that serum from patients enrolled in an ETEC H10407 controlled infection study are significantly more reactive with glycosylated YghJ compared to the non-glycosylated variant. This study provides an important link between O-linked glycosylation and the relative immunogenicity of bacterial proteins and further highlights the importance of this observation in considering ETEC proteins for inclusion in future broad coverage subunit vaccine candidates.
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Affiliation(s)
| | | | - Lars Vitved
- Department of Cancer and Inflammation Research, University of Southern Denmark, Odense, Denmark
| | - Arkadiusz Nawrocki
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | | | - Martin R. Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Subhra Chakraborty
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - A. Louis Bourgeois
- Center for Vaccine Innovation and Access, PATH, Washington, DC, United States
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13
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Mo J, Gao L, Zhang N, Xie J, Li D, Shan T, Fan L. Structural and quantitative alterations of gut microbiota in experimental small bowel obstruction. PLoS One 2021; 16:e0255651. [PMID: 34347831 PMCID: PMC8336877 DOI: 10.1371/journal.pone.0255651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 07/21/2021] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVE To investigate structural and quantitative alterations of gut microbiota in an experimental model of small bowel obstruction. METHOD A rat model of small bowel obstruction was established by using a polyvinyl chloride ring surgically placed surrounding the terminal ileum. The alterations of gut microbiota were studied after intestinal obstruction. Intraluminal fecal samples proximal to the obstruction were collected at different time points (24, 48 and 72 hours after obstruction) and analyzed by 16s rDNA high-throughput sequencing technology and quantitative PCR (qPCR) for target bacterial groups. Furthermore, intestinal claudin-1 mRNA expression was examined by real-time polymerase chain reaction analysis, and serum sIgA, IFABP and TFF3 levels were determined by enzyme-linked immunosorbent assay. RESULTS Small bowel obstruction led to significant bacterial overgrowth and profound alterations in gut microbiota composition and diversity. At the phylum level, the 16S rDNA sequences showed a marked decrease in the relative abundance of Firmicutes and increased abundance of Proteobacteria, Verrucomicrobia and Bacteroidetes. The qPCR analysis showed the absolute quantity of total bacteria increased significantly within 24 hours but did not change distinctly from 24 to 72 hours. Further indicators of intestinal mucosa damage and were observed as claudin-1 gene expression, sIgA and TFF3 levels decreased and IFABP level increased with prolonged obstruction. CONCLUSION Small bowel obstruction can cause significant structural and quantitative alterations of gut microbiota and induce disruption of gut mucosa barrier.
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MESH Headings
- Animals
- Bacteroidetes/genetics
- Claudin-1/genetics
- DNA, Bacterial/genetics
- DNA, Bacterial/isolation & purification
- DNA, Ribosomal/genetics
- DNA, Ribosomal/isolation & purification
- Disease Models, Animal
- Feces/microbiology
- Firmicutes/genetics
- Gastrointestinal Microbiome/genetics
- Gene Expression
- Ileum/microbiology
- Ileum/pathology
- Immunoglobulin A, Secretory/blood
- Immunoglobulin A, Secretory/metabolism
- Intestinal Mucosa/immunology
- Intestinal Mucosa/metabolism
- Intestinal Mucosa/microbiology
- Intestinal Obstruction/blood
- Intestinal Obstruction/microbiology
- Male
- Phylogeny
- Proteobacteria/genetics
- RNA, Ribosomal, 16S/genetics
- Rats
- Rats, Wistar
- Verrucomicrobia/genetics
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Affiliation(s)
- Jiali Mo
- Graduate school of Tianjin Medical University, Tianjin, China
| | - Lei Gao
- Graduate school of Tianjin Medical University, Tianjin, China
| | - Nan Zhang
- Department of Gastrointestinal Surgery, Nankai Hospital, Tianjin, China
| | - Jiliang Xie
- Department of Gastrointestinal Surgery, Nankai Hospital, Tianjin, China
| | - Donghua Li
- Department of Pharmacology, Tianjin Nankai Hospital, Tianjin, China
| | - Tao Shan
- Department of Gastrointestinal Surgery, Nankai Hospital, Tianjin, China
| | - Liuyang Fan
- Graduate school of Tianjin Medical University, Tianjin, China
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14
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Walker R, Kaminski RW, Porter C, Choy RKM, White JA, Fleckenstein JM, Cassels F, Bourgeois L. Vaccines for Protecting Infants from Bacterial Causes of Diarrheal Disease. Microorganisms 2021; 9:1382. [PMID: 34202102 PMCID: PMC8303436 DOI: 10.3390/microorganisms9071382] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 12/22/2022] Open
Abstract
The global diarrheal disease burden for Shigella, enterotoxigenic Escherichia coli (ETEC), and Campylobacter is estimated to be 88M, 75M, and 75M cases annually, respectively. A vaccine against this target trio of enteric pathogens could address about one-third of diarrhea cases in children. All three of these pathogens contribute to growth stunting and have demonstrated increasing resistance to antimicrobial agents. Several combinations of antigens are now recognized that could be effective for inducing protective immunity against each of the three target pathogens in a single vaccine for oral administration or parenteral injection. The vaccine combinations proposed here would result in a final product consistent with the World Health Organization's (WHO) preferred product characteristics for ETEC and Shigella vaccines, and improve the vaccine prospects for support from Gavi, the Vaccine Alliance, and widespread uptake by low- and middle-income countries' (LMIC) public health stakeholders. Broadly protective antigens will enable multi-pathogen vaccines to be efficiently developed and cost-effective. This review describes how emerging discoveries for each pathogen component of the target trio could be used to make vaccines, which could help reduce a major cause of poor health, reduced cognitive development, lost economic productivity, and poverty in many parts of the world.
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Affiliation(s)
- Richard Walker
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA;
| | - Robert W. Kaminski
- Department of Diarrheal Disease Research, Walter Reed Institute of Research, Silver Spring, MD 20910, USA;
| | - Chad Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD 20910, USA;
| | - Robert K. M. Choy
- Center for Vaccine Innovation and Access, PATH, San Francisco, CA 94108, USA;
| | - Jessica A. White
- Center for Vaccine Innovation and Access, PATH, Seattle, WA 98121, USA; (J.A.W.); (F.C.)
| | - James M. Fleckenstein
- Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA;
- Medicine Service, Saint Louis VA Health Care System, St. Louis, MO 63106, USA
| | - Fred Cassels
- Center for Vaccine Innovation and Access, PATH, Seattle, WA 98121, USA; (J.A.W.); (F.C.)
| | - Louis Bourgeois
- Center for Vaccine Innovation and Access, PATH, Washington, DC 20001, USA;
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15
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Bazhenova A, Gao F, Bolgiano B, Harding SE. Glycoconjugate vaccines against Salmonella enterica serovars and Shigella species: existing and emerging methods for their analysis. Biophys Rev 2021; 13:221-246. [PMID: 33868505 PMCID: PMC8035613 DOI: 10.1007/s12551-021-00791-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 02/25/2021] [Indexed: 12/26/2022] Open
Abstract
The global spread of enteric disease, the increasingly limited options for antimicrobial treatment and the need for effective eradication programs have resulted in an increased demand for glycoconjugate enteric vaccines, made with carbohydrate-based membrane components of the pathogen, and their precise characterisation. A set of physico-chemical and immunological tests are employed for complete vaccine characterisation and to ensure their consistency, potency, safety and stability, following the relevant World Health Organization and Pharmacopoeia guidelines. Variable requirements for analytical methods are linked to conjugate structure, carrier protein nature and size and O-acetyl content of polysaccharide. We investigated a key stability-indicating method which measures the percent free saccharide of Salmonella enterica subspecies enterica serovar Typhi capsular polysaccharide, by detergent precipitation, depolymerisation and HPAEC-PAD quantitation. Together with modern computational approaches, a more precise design of glycoconjugates is possible, allowing for improvements in solubility, structural conformation and stability, and immunogenicity of antigens, which may be applicable to a broad spectrum of vaccines. More validation experiments are required to establish the most effective and suitable methods for glycoconjugate analysis to bring uniformity to the existing protocols, although the need for product-specific approaches will apply, especially for the more complex vaccines. An overview of current and emerging analytical approaches for the characterisation of vaccines against Salmonella Typhi and Shigella species is described in this paper. This study should aid the development and licensing of new glycoconjugate vaccines aimed at the prevention of enteric diseases.
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Affiliation(s)
- Aleksandra Bazhenova
- School of Biosciences, University of Nottingham, Sutton Bonington, Loughborough, LE12 5RD UK
| | - Fang Gao
- Division of Bacteriology, National Institute for Biological Standards and Control (NIBSC), Blanche Lane, South Mimms, Potters Bar, EN6 3QG UK
| | - Barbara Bolgiano
- Division of Bacteriology, National Institute for Biological Standards and Control (NIBSC), Blanche Lane, South Mimms, Potters Bar, EN6 3QG UK
| | - Stephen E. Harding
- School of Biosciences, University of Nottingham, Sutton Bonington, Loughborough, LE12 5RD UK
- Museum of Cultural History, University of Oslo, Postboks 6762 St. Olavs plass, 0130 Oslo, Norway
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16
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Abstract
Enteric viral and bacterial infections continue to be a leading cause of mortality and morbidity in young children in low-income and middle-income countries, the elderly, and immunocompromised individuals. Vaccines are considered an effective and practical preventive approach against the predominantly fecal-to-oral transmitted gastroenteritis particularly in the resource-limited countries or regions where implementation of sanitation systems and supply of safe drinking water are not quickly achievable. While vaccines are available for a few enteric pathogens including rotavirus and cholera, there are no vaccines licensed for many other enteric viral and bacterial pathogens. Challenges in enteric vaccine development include immunological heterogeneity among pathogen strains or isolates, a lack of animal challenge models to evaluate vaccine candidacy, undefined host immune correlates to protection, and a low protective efficacy among young children in endemic regions. In this article, we briefly updated the progress and challenges in vaccines and vaccine development for the leading enteric viral and bacterial pathogens including rotavirus, human calicivirus, Shigella, enterotoxigenic Escherichia coli (ETEC), cholera, nontyphoidal Salmonella, and Campylobacter, and introduced a novel epitope- and structure-based vaccinology platform known as MEFA (multiepitope fusion antigen) and the application of MEFA for developing broadly protective multivalent vaccines against heterogenous pathogens.
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Affiliation(s)
- Hyesuk Seo
- University of Illinois at Urbana-Champaign, Department of Pathobiology, Urbana, Illinois, USA
| | - Qiangde Duan
- University of Yangzhou, Institute of Comparative Medicine, Yangzhou, PR China
| | - Weiping Zhang
- University of Illinois at Urbana-Champaign, Department of Pathobiology, Urbana, Illinois, USA,CONTACT Weiping Zhang, University of Illinois at Urbana-Champaign, Department of Pathobiology, Urbana, Illinois, USA
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17
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Heterologous expression of Intimin and IpaB fusion protein in Lactococcus lactis and its mucosal delivery elicit protection against pathogenicity of Escherichia coli O157 and Shigella flexneri in a murine model. Int Immunopharmacol 2020; 85:106617. [PMID: 32464569 DOI: 10.1016/j.intimp.2020.106617] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/16/2020] [Accepted: 05/17/2020] [Indexed: 12/12/2022]
Abstract
Escherichia coli O157:H7 and Shigella flexneri are the predominant diarrhoeal pathogens and those strains producing Shiga toxins cause life-threatening sequelae including hemolytic uremic syndrome (HUS) upon their entry into the host. Intimate adherence of E. coli O157 and invasion of S. flexneri in the host intestinal epithelial cells is mainly mediated by Intimin and IpaB proteins, respectively. In this study, we have synthesized chimera of immunodominant regions of Intimin (eae) and IpaB (ipaB) designated as EI and expressed it in Lactococcus lactis (LL-EI) to develop a combinatorial oral vaccine candidate. Immune parameters and protective efficacy of orally administered LL-EI were assessed in the murine model. Significant EI-specific serum IgG, IgA, and fecal IgA antibody titer were observed in the LL-EI group. Considerable increase in EI-specific splenocyte proliferation and a concurrent upregulation of both Th1 and Th2 cytokines was observed in LL-EI immunized mice. Flow cytometry analysis also revealed a significant increase in CD4 and CD8 cell counts in LL-EI immunized group compared to PBS, LL control group.In vitro studies using LL-EI immunized mice sera showed substantial protection against bacterial adhesion and invasion caused by E. coli O157 and Shigella flexneri¸ respectively. LL-EI immunized group challenged with E. coli O157 ceased fecal shedding within 6 days, and mice challenged with S. flexneri showed 93% survival with minimal bacterial load in the lungs. Our results indicate that LL-EI immunization elicits systemic, mucosal and cell-mediated immune responses, and can be a promising candidate for oral vaccine development against these pathogens.
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18
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Beg S, Alharbi KS, Alruwaili NK, Alotaibi NH, Almalki WH, Alenezi SK, Altowayan WM, Alshammari MS, Rahman M. Nanotherapeutic systems for delivering cancer vaccines: recent advances. Nanomedicine (Lond) 2020; 15:1527-1537. [PMID: 32410483 DOI: 10.2217/nnm-2020-0046] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
With an increase in the global burden of cancer-related deaths, the quest for developing new therapeutic solutions has taken momentum. In this regard, the idea of using cancer vaccines came to existence approximately 30 years ago, where gene therapy interventions have shown significant improvement in the therapeutic outcomes against several types of cancers. Cancer vaccines usually encounter a number of challenges with limited targeting ability to the tumors. Nanocarriers have been studied as a technological innovation for tumor targeting of gene therapeutics. This article provides a critical insight into the recent progress made in nanotherapeutic strategies for genetic vaccine delivery for treatment against various types of cancers. Moreover, the article intends to provide a summary of the research work being done on this topic.
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Affiliation(s)
- Sarwar Beg
- Department of Pharmaceutics, School of Pharmaceutical Education & Research, Jamia Hamdard, New Delhi, India
| | - Khalid S Alharbi
- Department of Pharmacology, College of Pharmacy, Jouf University, Sakakah, Saudi Arabia
| | - Nabil K Alruwaili
- Department of Pharmaceutics, College of Pharmacy, Jouf University, Sakakah, Saudi Arabia
| | - Nasser Hadal Alotaibi
- Department of Clinical Pharmacy, College of Pharmacy, Jouf University, Sakakah, Saudi Arabia
| | - Waleed H Almalki
- Department of Pharmacology & Toxicology, College of Pharmacy, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Sattam K Alenezi
- Department of Pharmacology & Toxicology, Unaizah College of Pharmacy, Qassim University, Qassim, Saudi Arabia
| | - Waleed M Altowayan
- Department of Pharmacy Practice, College of Pharmacy, Qassim University, Qassim, Saudi Arabia
| | - Mohammed S Alshammari
- Department of Pharmacy Practice, Unaizah College of Pharmacy, Qassim University, Qassim, Saudi Arabia
| | - Mahfoozur Rahman
- Department of Pharmaceutical Sciences, SIHAS, Faculty of Health Science, Sam Higginbottom University of Agriculture, Technology & Sciences, Allahabad, India
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19
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Ranjbar R, Farahani A. Shigella: Antibiotic-Resistance Mechanisms And New Horizons For Treatment. Infect Drug Resist 2019; 12:3137-3167. [PMID: 31632102 PMCID: PMC6789722 DOI: 10.2147/idr.s219755] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 08/28/2019] [Indexed: 12/17/2022] Open
Abstract
Shigella spp. are a common cause of diarrheal disease and have remained an important pathogen responsible for increased rates of morbidity and mortality caused by dysentery each year around the globe. Antibiotic treatment of Shigella infections plays an essential role in reducing prevalence and death rates of the disease. However, treatment of these infections remains a challenge, due to the global rise in broad-spectrum resistance to many antibiotics. Drug resistance in Shigella spp. can result from many mechanisms, such as decrease in cellular permeability, extrusion of drugs by active efflux pumps, and overexpression of drug-modifying and -inactivating enzymes or target modification by mutation. Therefore, there is an increasing need for identification and evolution of alternative therapeutic strategies presenting innovative avenues against Shigella infections, as well as paying further attention to this infection. The current review focuses on various antibiotic-resistance mechanisms of Shigella spp. with a particular emphasis on epidemiology and new mechanisms of resistance and their acquisition, and also discusses the status of novel strategies for treatment of Shigella infection and vaccine candidates currently under evaluation in preclinical or clinical phases.
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Affiliation(s)
- Reza Ranjbar
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Abbas Farahani
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
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