1
|
Kulkarni PS, Potey AV, Bharati S, Kunhihitlu A, Narasimha B, Yallapa S, Dharmadhikari A, Gavade V, Kamat CD, Mallya A, Sarma AD, Goel S, Pisal SS, Poonawalla CS, Venkatesan R, Jones E, Flaxman A, Kim YC, Pollard AJ. The safety and immunogenicity of a bivalent conjugate vaccine against Salmonella enterica Typhi and Paratyphi A in healthy Indian adults: a phase 1, randomised, active-controlled, double-blind trial. Lancet 2024; 403:1554-1562. [PMID: 38555928 DOI: 10.1016/s0140-6736(24)00249-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 01/12/2024] [Accepted: 02/06/2024] [Indexed: 04/02/2024]
Abstract
BACKGROUND Enteric fever caused by Salmonella enterica Typhi and Salmonella Paratyphi A is an important public health problem, especially in low-income and middle-income countries with limited access to safe water and sanitation. We present results from, to our knowledge, the first ever human study of a bivalent paratyphoid A-typhoid conjugate vaccine (Sii-PTCV). METHODS In this double-blind phase 1 study, 60 healthy Indian adults were randomly assigned (1:1) to receive a single intramuscular dose of either Sii-PTCV or typhoid conjugate vaccine (Typbar-TCV). Safety was assessed by observing solicited adverse events for 1 week, unsolicited events for 1 month, and serious adverse events (SAEs) over 6 months. Immunogenicity at 1 month and 6 months was assessed by measuring anti-capsular polysaccharide antigen Vi (anti-Vi) IgG and IgA against Salmonella Typhi and anti-lipopolysaccharide (LPS) IgG against Salmonella Paratyphi A by ELISA, and functional antibodies using serum bactericidal assay (SBA) against Salmonella Paratyphi A. This study is registered with Clinical Trial Registry-India (CTRI/2022/06/043608) and is completed. FINDINGS 60 participants were enrolled. Of these 60 participants, 57 (95%) participants were male and three (5%) participants were female. Solicited adverse events were observed in 27 (90%) of 30 participants who received Sii-PTCV and 26 (87%) of 30 participants who received Typbar-TCV. The most common local solicited event was pain in 27 (90%) participants who received Sii-PTCV and in 23 (77%) participants who received Typbar-TCV. The most common solicited systemic event was myalgia in five (17%) participants who received Sii-PTCV, whereas four (13%) participants who received Typbar-TCV had myalgia and four (13%) had headache. No vaccine-related unsolicited adverse events or SAEs were reported. The seroconversion rates on day 29 were 96·7% (95% CI 82·8-99·9) with Sii-PTCV and 100·0% (88·4-100·0) with Typbar-TCV for anti-Vi IgG; 93·3% (77·9-99·2) with Sii-PTCV and 100·0% (88·4-100·0) with Typbar-TCV for anti-Vi IgA; 100·0% (88·4-100·0) with Sii-PTCV and 3·3% (0·1-17·2) with Typbar-TCV for anti-LPS (paratyphoid); and 93·3% (77·9-99·2) with Sii-PTCV and 0% (0·0-11·6) with Typbar-TCV for SBA titres (paratyphoid). Paratyphoid anti-LPS immune responses were sustained at day 181. INTERPRETATION Sii-PTCV was safe and immunogenic for both typhoid and paratyphoid antigens indicating its potential for providing comprehensive protection against enteric fever. FUNDING Serum Institute of India.
Collapse
|
2
|
Smith C, Smith E, Rydlova A, Varro R, Hinton JCD, Gordon MA, Choy RKM, Liu X, Pollard AJ, Chiu C, Cooke GS, Gibani MM. Protocol for the challenge non-typhoidal Salmonella (CHANTS) study: a first-in-human, in-patient, double-blind, randomised, safety and dose-escalation controlled human infection model in the UK. BMJ Open 2024; 14:e076477. [PMID: 38199617 PMCID: PMC10806722 DOI: 10.1136/bmjopen-2023-076477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
INTRODUCTION Invasive non-typhoidal Salmonella (iNTS) serovars are a major cause of community-acquired bloodstream infections in sub-Saharan Africa (SSA). In this setting, Salmonella enterica serovar Typhimurium accounts for two-thirds of infections and is associated with an estimated case fatality rate of 15%-20%. Several iNTS vaccine candidates are in early-stage assessment which-if found effective-would provide a valuable public health tool to reduce iNTS disease burden. The CHANTS study aims to develop a first-in-human Salmonella Typhimurium controlled human infection model, which can act as a platform for future vaccine evaluation, in addition to providing novel insights into iNTS disease pathogenesis. METHODS AND ANALYSIS This double-blind, safety and dose-escalation study will randomise 40-80 healthy UK participants aged 18-50 to receive oral challenge with one of two strains of S. Typhimurium belonging to the ST19 (strain 4/74) or ST313 (strain D23580) lineages. 4/74 is a global strain often associated with diarrhoeal illness predominantly in high-income settings, while D23580 is an archetypal strain representing invasive disease-causing isolates found in SSA. The primary objective is to determine the minimum infectious dose (colony-forming unit) required for 60%-75% of participants to develop clinical or microbiological features of systemic salmonellosis. Secondary endpoints are to describe and compare the clinical, microbiological and immunological responses following challenge. Dose escalation or de-escalation will be undertaken by continual-reassessment methodology and limited within prespecified safety thresholds. Exploratory objectives are to describe mechanisms of iNTS virulence, identify putative immune correlates of protection and describe host-pathogen interactions in response to infection. ETHICS AND DISSEMINATION Ethical approval has been obtained from the NHS Health Research Authority (London-Fulham Research Ethics Committee 21/PR/0051; IRAS Project ID 301659). The study findings will be disseminated in international peer-reviewed journals and presented at national/international stakeholder meetings. Study outcome summaries will be provided to both funders and participants. TRIAL REGISTRATION NUMBER NCT05870150.
Collapse
Affiliation(s)
- Christopher Smith
- Department of Infectious Disease, Imperial College London, London, UK
| | - Emma Smith
- Department of Infectious Disease, Imperial College London, London, UK
| | - Anna Rydlova
- Department of Infectious Disease, Imperial College London, London, UK
| | - Robert Varro
- Department of Infectious Disease, Imperial College London, London, UK
| | - Jay C D Hinton
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Melita A Gordon
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
- Malawi Liverpool Wellcome Trust Clinical Research Programme, Kamuzu University of Health Sciences, Blantyre, Southern Region, Malawi
| | | | - Xinxue Liu
- Oxford Vaccine Group, Department of Paediatrics, Oxford University, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, Oxford University, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Christopher Chiu
- Department of Infectious Disease, Imperial College London, London, UK
| | - Graham S Cooke
- Department of Infectious Disease, Imperial College London, London, UK
| | - Malick M Gibani
- Department of Infectious Disease, Imperial College London, London, UK
| |
Collapse
|
3
|
Meiring JE, Khanam F, Basnyat B, Charles RC, Crump JA, Debellut F, Holt KE, Kariuki S, Mugisha E, Neuzil KM, Parry CM, Pitzer VE, Pollard AJ, Qadri F, Gordon MA. Typhoid fever. Nat Rev Dis Primers 2023; 9:71. [PMID: 38097589 DOI: 10.1038/s41572-023-00480-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/06/2023] [Indexed: 12/18/2023]
Abstract
Typhoid fever is an invasive bacterial disease associated with bloodstream infection that causes a high burden of disease in Africa and Asia. Typhoid primarily affects individuals ranging from infants through to young adults. The causative organism, Salmonella enterica subsp. enterica serovar Typhi is transmitted via the faecal-oral route, crossing the intestinal epithelium and disseminating to systemic and intracellular sites, causing an undifferentiated febrile illness. Blood culture remains the practical reference standard for diagnosis of typhoid fever, where culture testing is available, but novel diagnostic modalities are an important priority under investigation. Since 2017, remarkable progress has been made in defining the global burden of both typhoid fever and antimicrobial resistance; in understanding disease pathogenesis and immunological protection through the use of controlled human infection; and in advancing effective vaccination programmes through strategic multipartner collaboration and targeted clinical trials in multiple high-incidence priority settings. This Primer thus offers a timely update of progress and perspective on future priorities for the global scientific community.
Collapse
Affiliation(s)
- James E Meiring
- Division of Clinical Medicine, School of Medicine and Population Health, University of Sheffield, Sheffield, UK
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi
| | - Farhana Khanam
- International Centre for Diarrhoel Disease Research, Dhaka, Bangladesh
| | - Buddha Basnyat
- Oxford University Clinical Research Unit, Kathmandu, Nepal
| | - Richelle C Charles
- Massachusetts General Hospital, Harvard Medical School, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - John A Crump
- Centre for International Health, University of Otago, Dunedin, New Zealand
| | | | - Kathryn E Holt
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Samuel Kariuki
- Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Emmanuel Mugisha
- Center for Vaccine Innovation and Access, PATH, Seattle, WA, USA
| | - Kathleen M Neuzil
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Christopher M Parry
- Department of Clinical Sciences and Education, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Virginia E Pitzer
- Department of Epidemiology of Microbial Diseases and Public Health Modelling Unit, Yale School of Public Health, Yale University, New Haven, CT, USA
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Firdausi Qadri
- International Centre for Diarrhoel Disease Research, Dhaka, Bangladesh
| | - Melita A Gordon
- Malawi-Liverpool-Wellcome Programme, Blantyre, Malawi.
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK.
| |
Collapse
|
4
|
Martin LB, Khanam F, Qadri F, Khalil I, Sikorski MJ, Baker S. Vaccine value profile for Salmonella enterica serovar Paratyphi A. Vaccine 2023; 41 Suppl 2:S114-S133. [PMID: 37951691 DOI: 10.1016/j.vaccine.2023.01.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 12/27/2022] [Accepted: 01/23/2023] [Indexed: 11/14/2023]
Abstract
In Asia, there are an estimated 12 million annual cases of enteric fever, a potentially fatal systemic bacterial infection caused by Salmonella enterica serovars Typhi (STy) and Paratyphi A (SPA). The recent availability of typhoid conjugate vaccines (TCV), an increasing incidence of disease caused by SPA and growing antimicrobial resistance (AMR) across the genus Salmonella makes a bivalent STy/SPA vaccine a useful public health proposition. The uptake of a stand-alone paratyphoid vaccine is likely low thus, there is a pipeline of bivalent STy/SPA candidate vaccines. Several candidates are close to entering clinical trials, which if successful should facilitate a more comprehensive approach for enteric fever control. Additionally, the World Health Organization (WHO) has made advancing the development of vaccines that protect young children and working aged adults against both agents of enteric fever a priority objective. This "Vaccine Value Profile" (VVP) addresses information related predominantly to invasive disease caused by SPA prevalent in Asia. Information is included on stand-alone SPA candidate vaccines and candidate vaccines targeting SPA combined with STy. Out of scope for the first version of this VVP is a wider discussion on the development of a universal Salmonella combination candidate vaccine, addressing both enteric fever and invasive non-typhoidal Salmonella disease, for use globally. This VVP is a detailed, high-level assessment of existing, publicly available information to inform and contextualize the public health, economic, and societal potential of pipeline vaccines and vaccine-like products for SPA. Future versions of this VVP will be updated to reflect ongoing activities such as vaccine development strategies and "Full Vaccine Value Assessment" that will inform the value proposition of an SPA vaccine. This VVP was developed by an expert working group from academia, non-profit organizations, public-private partnerships, and multi-lateral organizations as well as in collaboration with stakeholders from the WHO South-East Asian Region. All contributors have extensive expertise on various elements of the VVP for SPA and collectively aimed to identify current research and knowledge gaps.
Collapse
Affiliation(s)
- Laura B Martin
- Independent Consultant (current affiliation US Pharmacopeia Convention), USA.
| | - Farhana Khanam
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Bangladesh.
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Bangladesh.
| | | | | | - Stephen Baker
- University of Cambridge School of Clinical Medicine, UK.
| |
Collapse
|
5
|
Barton A, Hill J, O'Connor D, Jones C, Jones E, Camara S, Shrestha S, Jin C, Gibani MM, Dobinson HC, Waddington C, Darton TC, Blohmke CJ, Pollard AJ. Early transcriptional responses to human enteric fever challenge. Infect Immun 2023; 91:e0010823. [PMID: 37725060 PMCID: PMC10581002 DOI: 10.1128/iai.00108-23] [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: 03/23/2023] [Accepted: 06/29/2023] [Indexed: 09/21/2023] Open
Abstract
Enteric fever, caused by oral infection with typhoidal Salmonella serovars, presents as a non-specific febrile illness preceded by an incubation period of 5 days or more. The enteric fever human challenge model provides a unique opportunity to investigate the innate immune response during this incubation period, and how this response is altered by vaccination with the Vi polysaccharide or conjugate vaccine. We find that on the same day as ingestion of typhoidal Salmonella, there is already evidence of an immune response, with 199 genes upregulated in the peripheral blood transcriptome 12 hours post-challenge (false discovery rate <0.05). Gene sets relating to neutrophils, monocytes, and innate immunity were over-represented (false discovery rate <0.05). Estimating cell proportions from gene expression data suggested a possible increase in activated monocytes 12 hours post-challenge (P = 0.036, paired Wilcoxon signed-rank test). Furthermore, plasma TNF-α rose following exposure (P = 0.011, paired Wilcoxon signed-rank test). There were no significant differences in gene expression (false discovery rate <0.05) in the 12 hours response between those who did and did not subsequently develop clinical or blood culture confirmed enteric fever or between vaccination groups. Together, these results demonstrate early perturbation of the peripheral blood transcriptome after enteric fever challenge and provide initial insight into early mechanisms of protection.
Collapse
Affiliation(s)
- Amber Barton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Jennifer Hill
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Daniel O'Connor
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Claire Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Elizabeth Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Susana Camara
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Sonu Shrestha
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Celina Jin
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Pathology, Royal Melbourne Hospital, Melbourne, Australia
- Infectious Diseases and Immune Defence Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Malick M. Gibani
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infectious Disease, Imperial College, London, United Kingdom
| | - Hazel C. Dobinson
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Claire Waddington
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infectious Disease, Imperial College, London, United Kingdom
| | - Thomas C. Darton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infection, Immunity and Cardiovascular Disease and The Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Christoph J. Blohmke
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Andrew J. Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| |
Collapse
|
6
|
Niewold P, Dijkstra DJ, Cai Y, Goletti D, Palmieri F, van Meijgaarden KE, Verreck FAW, Akkerman OW, Hofland RW, Delemarre EM, Nierkens S, Verheul MK, Pollard AJ, van Dissel JT, Ottenhoff THM, Trouw LA, Joosten SA. Identification of circulating monocytes as producers of tuberculosis disease biomarker C1q. Sci Rep 2023; 13:11617. [PMID: 37464009 DOI: 10.1038/s41598-023-38889-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 07/17/2023] [Indexed: 07/20/2023] Open
Abstract
Tuberculosis (TB) is a prevalent disease causing an estimated 1.6 million deaths and 10.6 million new cases annually. Discriminating TB disease from differential diagnoses can be complex, particularly in the field. Increased levels of complement component C1q in serum have been identified as a specific and accessible biomarker for TB disease but the source of C1q in circulation has not been identified. Here, data and samples previously collected from human cohorts, a clinical trial and a non-human primate study were used to identify cells producing C1q in circulation. Cell subset frequencies were correlated with serum C1q levels and combined with single cell RNA sequencing and flow cytometry analyses. This identified monocytes as C1q producers in circulation, with a pronounced expression of C1q in classical and intermediate monocytes and variable expression in non-classical monocytes.
Collapse
Affiliation(s)
- Paula Niewold
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, the Netherlands.
| | - Douwe J Dijkstra
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | - Yi Cai
- Guangdong Key Laboratory of Regional Immunity and Diseases, Department of Pathogen Biology, Shenzhen University Medical School, Shenzhen, China
| | - Delia Goletti
- Translational Research Unit, Department of Epidemiology and Preclinical Research, National Institute for Infectious Diseases, Rome, Italy
| | - Fabrizio Palmieri
- Respiratory Infectious Diseases Unit, Clinical Department, National Institute for Infectious Diseases, Rome, Italy
| | | | - Frank A W Verreck
- Section of TB Research & Immunology, Department of Parasitology, Biomedical Primate Research Centre (BPRC), Rijswijk, the Netherlands
| | - Onno W Akkerman
- Department of Pulmonary Disease and Tuberculosis, University of Groningen, Groningen, the Netherlands
- Tuberculosis Center Beatrixoord, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Regina W Hofland
- Department of Pulmonary Diseases and Tuberculosis, University Medical Center Utrecht, Utrecht, the Netherlands
| | | | - Stefan Nierkens
- Center for Translational Immunology, UMC Utrecht, Utrecht, the Netherlands
- Princess Máxima Center for Pediatric Oncology, Utrecht, the Netherlands
| | - Marije K Verheul
- Oxford Vaccine Group, Department of Pediatrics, University of Oxford and NIHR Oxford Biomedical Research Centre, Oxford, UK
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, 3720 BA, The Netherlands
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Pediatrics, University of Oxford and NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Jaap T van Dissel
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, the Netherlands
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, 3720 BA, The Netherlands
| | - Tom H M Ottenhoff
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, the Netherlands
| | - Leendert A Trouw
- Department of Immunology, Leiden University Medical Center, Leiden, the Netherlands
| | - Simone A Joosten
- Department of Infectious Diseases, Leiden University Medical Center, Leiden, the Netherlands
| |
Collapse
|
7
|
McCann N, Emary K, Singh N, Mclean F, Camara S, Jones E, Kim YC, Liu X, Greenland M, Conlin K, Hill J, Verheul M, Robinson H, Angus B, Ramasamy MN, Levine MM, Pollard AJ. Accelerating clinical development of a live attenuated vaccine against Salmonella Paratyphi A (VASP): study protocol for an observer-participant-blind randomised control trial of a novel oral vaccine using a human challenge model of Salmonella Paratyphi A infection in healthy adult volunteers. BMJ Open 2023; 13:e068966. [PMID: 37225278 DOI: 10.1136/bmjopen-2022-068966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
INTRODUCTION This is the first efficacy study of an oral live attenuated vaccine against Salmonella Paratyphi A using a human challenge model of paratyphoid infection. S. Paratyphi A is responsible for 3.3 million cases of enteric fever every year, with over 19 000 deaths. Although improvements to sanitation and access to clean water are vital to reduce the burden of this condition, vaccination offers a cost-effective, medium-term solution. Efficacy trials of potential S. Paratyphi vaccine candidates in the field are unlikely to be feasible given the large number of participants required. Human challenge models therefore offer a unique, cost-effective solution to test efficacy of such vaccines. METHODS AND ANALYSIS This is an observer-blind, randomised, placebo-controlled trial phase I/II of the oral live-attenuated vaccine against S. Paratyphi A, CVD 1902. Volunteers will be randomised 1:1 to receive two doses of CVD 1902 or placebo, 14 days apart. One month following second vaccination all volunteers will ingest S. Paratyphi A bacteria with a bicarbonate buffer solution. They will be reviewed daily in the following 14 days and diagnosed with paratyphoid infection if the predefined microbiological or clinical diagnostic criteria are met. All participants will be treated with antibiotics on diagnosis, or at day 14 postchallenge if not diagnosed. The vaccine efficacy will be determined by comparing the relative attack rate, that is, the proportion of those diagnosed with paratyphoid infection, in the vaccine and placebo groups. ETHICS AND DISSEMINATION Ethical approval for this study has been obtained from the Berkshire Medical Research Ethics Committee (REC ref 21/SC/0330). The results will be disseminated via publication in a peer-reviewed journal and presentation at international conferences. TRIAL REGISTRATION NUMBER ISRCTN15485902.
Collapse
Affiliation(s)
- Naina McCann
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Katherine Emary
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Nisha Singh
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Florence Mclean
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Susana Camara
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Elizabeth Jones
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Young Chan Kim
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Xinxue Liu
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Melanie Greenland
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Kerry Conlin
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Jennifer Hill
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Marije Verheul
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Hannah Robinson
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Brian Angus
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Maheshi N Ramasamy
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| | - Myron M Levine
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Andrew J Pollard
- Department of Paediatrics, Oxford Vaccine Group, University of Oxford, Oxford, UK
- NIHR Oxford Biomedical Research Centre, Oxford, UK
| |
Collapse
|
8
|
Sztein MB, Booth JS. Controlled human infectious models, a path forward in uncovering immunological correlates of protection: Lessons from enteric fevers studies. Front Microbiol 2022; 13:983403. [PMID: 36204615 PMCID: PMC9530043 DOI: 10.3389/fmicb.2022.983403] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/24/2022] [Indexed: 11/13/2022] Open
Abstract
Enteric infectious diseases account for more than a billion disease episodes yearly worldwide resulting in approximately 2 million deaths, with children under 5 years old and the elderly being disproportionally affected. Enteric pathogens comprise viruses, parasites, and bacteria; the latter including pathogens such as Salmonella [typhoidal (TS) and non-typhoidal (nTS)], cholera, Shigella and multiple pathotypes of Escherichia coli (E. coli). In addition, multi-drug resistant and extensively drug-resistant (XDR) strains (e.g., S. Typhi H58 strain) of enteric bacteria are emerging; thus, renewed efforts to tackle enteric diseases are required. Many of these entero-pathogens could be controlled by oral or parenteral vaccines; however, development of new, effective vaccines has been hampered by lack of known immunological correlates of protection (CoP) and limited knowledge of the factors contributing to protective responses. To fully comprehend the human response to enteric infections, an invaluable tool that has recently re-emerged is the use of controlled human infection models (CHIMs) in which participants are challenged with virulent wild-type (wt) organisms. CHIMs have the potential to uncover immune mechanisms and identify CoP to enteric pathogens, as well as to evaluate the efficacy of therapeutics and vaccines in humans. CHIMs have been used to provide invaluable insights in the pathogenesis, host-pathogen interaction and evaluation of vaccines. Recently, several Oxford typhoid CHIM studies have been performed to assess the role of multiple cell types (B cells, CD8+ T, Tregs, MAIT, Monocytes and DC) during S. Typhi infection. One of the key messages that emerged from these studies is that baseline antigen-specific responses are important in that they can correlate with clinical outcomes. Additionally, volunteers who develop typhoid disease (TD) exhibit higher levels and more activated cell types (e.g., DC and monocytes) which are nevertheless defective in discrete signaling pathways. Future critical aspects of this research will involve the study of immune responses to enteric infections at the site of entry, i.e., the intestinal mucosa. This review will describe our current knowledge of immunity to enteric fevers caused byS. Typhi and S. Paratyphi A, with emphasis on the contributions of CHIMs to uncover the complex immunological responses to these organisms and provide insights into the determinants of protective immunity.
Collapse
Affiliation(s)
- Marcelo B. Sztein
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
- *Correspondence: Marcelo B. Sztein,
| | - Jayaum S. Booth
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
- Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD, United States
- Jayaum S. Booth,
| |
Collapse
|
9
|
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.
Collapse
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,
| |
Collapse
|
10
|
Clarkson KA, Porter CK, Talaat KR, Kapulu MC, Chen WH, Frenck RW, Bourgeois AL, Kaminski RW, Martin LB. Shigella-Controlled Human Infection Models: Current and Future Perspectives. Curr Top Microbiol Immunol 2022. [PMID: 35616717 PMCID: PMC7616482 DOI: 10.1007/82_2021_248] [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] [Indexed: 10/18/2022]
Abstract
Shigella-controlled human infection models (CHIMs) are an invaluable tool utilized by the vaccine community to combat one of the leading global causes of infectious diarrhea, which affects infants, children and adults regardless of socioeconomic status. The impact of shigellosis disproportionately affects children in low- and middle-income countries (LMICs) resulting in cognitive and physical stunting, perpetuating a cycle that must be halted. Shigella-CHIMs not only facilitate the early evaluation of enteric countermeasures and up-selection of the most promising products but also provide insight into mechanisms of infection and immunity that are not possible utilizing animal models or in vitro systems. The greater understanding of shigellosis obtained in CHIMs builds and empowers the development of new generation solutions to global health issues which are unattainable in the conventional laboratory and clinical settings. Therefore, refining, mining and expansion of safe and reproducible infection models hold the potential to create effective means to end diarrheal disease and associated co-morbidities associated with Shigella infection.
Collapse
Affiliation(s)
- Kristen A Clarkson
- Department of Diarrheal Disease Research, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Chad K Porter
- Enteric Disease Department, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Kawsar R Talaat
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, 624 North Broadway Street Hampton House, Baltimore, MD, 21205, USA
| | - Melissa C Kapulu
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi County Hospital, Off Bofa Road, Kilifi, 80108, Kenya
| | - Wilbur H Chen
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 West Baltimore Street, Baltimore, MD, 21201, USA
| | - Robert W Frenck
- Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - A Louis Bourgeois
- PATH Center for Vaccine Innovation and Access, 455 Massachusetts Avenue NW, Washington, DC, 20001, USA
| | - Robert W Kaminski
- Department of Diarrheal Disease Research, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Laura B Martin
- GSK Vaccines Institute for Global Health, Via Fiorentina 1, 53100, Siena, Italy.
| |
Collapse
|
11
|
Barton A, Hill J, Bibi S, Chen L, Jones C, Jones E, Camara S, Shrestha S, Jin C, Gibani MM, Dobinson H, Waddington C, Darton TC, Blohmke CJ, Pollard AJ. Genetic Susceptibility to Enteric Fever in Experimentally Challenged Human Volunteers. Infect Immun 2022; 90:e0038921. [PMID: 35254093 PMCID: PMC9022534 DOI: 10.1128/iai.00389-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 01/24/2022] [Indexed: 12/16/2022] Open
Abstract
Infections with Salmonella enterica serovars Typhi and Paratyphi A cause an estimated 14 million cases of enteric fever annually. Here, the controlled nature of challenge studies is exploited to identify genetic variants associated with enteric fever susceptibility. Human challenge participants were genotyped by Illumina OmniExpress-24 BeadChip array (n = 176) and/or transcriptionally profiled by RNA sequencing (n = 174). While the study was underpowered to detect any single nucleotide polymorphisms (SNPs) significant at the whole-genome level, two SNPs within CAPN14 and MIATNB were identified with P < 10-5 for association with development of symptoms or bacteremia following oral S. Typhi or S. Paratyphi A challenge. Imputation of classical human leukocyte antigen (HLA) types from genomic and transcriptomic data identified HLA-B*27:05, previously associated with nontyphoidal Salmonella-induced reactive arthritis, as the HLA type most strongly associated with enteric fever susceptibility (P = 0.011). Gene sets relating to the unfolded protein response/heat shock and endoplasmic reticulum-associated protein degradation were overrepresented in HLA-B*27:05+ participants following challenge. Furthermore, intracellular replication of S. Typhi is higher in C1R cells transfected with HLA-B*27:05 (P = 0.02). These data suggest that activation of the unfolded protein response by HLA-B*27:05 misfolding may create an intracellular environment conducive to S. Typhi replication, increasing susceptibility to enteric fever.
Collapse
Affiliation(s)
- Amber Barton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Clinical Research Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jennifer Hill
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Sagida Bibi
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Liye Chen
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
| | - Claire Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Elizabeth Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Susana Camara
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Sonu Shrestha
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Celina Jin
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Malick M. Gibani
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Hazel Dobinson
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Claire Waddington
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Thomas C. Darton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
- Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
- Florey Institute for Host-Pathogen Interactions, University of Sheffield, Sheffield, United Kingdom
| | - Christoph J. Blohmke
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Andrew J. Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| |
Collapse
|
12
|
Ryckman T, Karthikeyan AS, Kumar D, Cao Y, Kang G, Goldhaber-Fiebert JD, John J, Lo NC, Andrews JR. Comparison of Strategies for Typhoid Conjugate Vaccine Introduction in India: A Cost-Effectiveness Modeling Study. J Infect Dis 2021; 224:S612-S624. [PMID: 35238367 PMCID: PMC8892534 DOI: 10.1093/infdis/jiab150] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Typhoid fever causes substantial global mortality, with almost half occurring in India. New typhoid vaccines are highly effective and recommended by the World Health Organization for high-burden settings. There is a need to determine whether and which typhoid vaccine strategies should be implemented in India. METHODS We assessed typhoid vaccination using a dynamic compartmental model, parameterized by and calibrated to disease and costing data from a recent multisite surveillance study in India. We modeled routine and 1-time campaign strategies that target different ages and settings. The primary outcome was cost-effectiveness, measured by incremental cost-effectiveness ratios (ICERs) benchmarked against India's gross national income per capita (US$2130). RESULTS Both routine and campaign vaccination strategies were cost-saving compared to the status quo, due to averted costs of illness. The preferred strategy was a nationwide community-based catchup campaign targeting children aged 1-15 years alongside routine vaccination, with an ICER of $929 per disability-adjusted life-year averted. Over the first 10 years of implementation, vaccination could avert 21-39 million cases and save $1.6-$2.2 billion. These findings were broadly consistent across willingness-to-pay thresholds, epidemiologic settings, and model input distributions. CONCLUSIONS Despite high initial costs, routine and campaign typhoid vaccination in India could substantially reduce mortality and was highly cost-effective.
Collapse
Affiliation(s)
- Theresa Ryckman
- Stanford Health Policy, Center for Health Policy and Center for Primary Care and Outcomes Research, Stanford University School of Medicine and the Freeman Spogli Institute, Stanford, California, USA
| | - Arun S Karthikeyan
- Wellcome Trust Research Laboratory, Christian Medical College, Vellore, Tamil Nadu, India
| | - Dilesh Kumar
- Wellcome Trust Research Laboratory, Christian Medical College, Vellore, Tamil Nadu, India
| | - Yanjia Cao
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| | - Gagandeep Kang
- Wellcome Trust Research Laboratory, Christian Medical College, Vellore, Tamil Nadu, India
| | - Jeremy D Goldhaber-Fiebert
- Stanford Health Policy, Center for Health Policy and Center for Primary Care and Outcomes Research, Stanford University School of Medicine and the Freeman Spogli Institute, Stanford, California, USA
| | - Jacob John
- Department of Community Health, Christian Medical College, Vellore, Tamil Nadu, India
| | - Nathan C Lo
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA
| | - Jason R Andrews
- Division of Infectious Diseases and Geographic Medicine, Stanford University School of Medicine, Stanford, California, USA
| |
Collapse
|
13
|
Porter CK, Talaat KR, Isidean SD, Kardinaal A, Chakraborty S, Gutiérrez RL, Sack DA, Bourgeois AL. The Controlled Human Infection Model for Enterotoxigenic Escherichia coli. Curr Top Microbiol Immunol 2021. [PMID: 34669040 DOI: 10.1007/82_2021_242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The controlled human infection model (CHIM) for enterotoxigenic Escherichia coli (ETEC) has been instrumental in defining ETEC as a causative agent of acute watery diarrhea, providing insights into disease pathogenesis and resistance to illness, and enabling preliminary efficacy evaluations for numerous products including vaccines, immunoprophylactics, and drugs. Over a dozen strains have been evaluated to date, with a spectrum of clinical signs and symptoms that appear to replicate the clinical illness seen with naturally occurring ETEC. Recent advancements in the ETEC CHIM have enhanced the characterization of clinical, immunological, and microbiological outcomes. It is anticipated that omics-based technologies applied to ETEC CHIMs will continue to broaden our understanding of host-pathogen interactions and facilitate the development of primary and secondary prevention strategies.
Collapse
Affiliation(s)
- Chad K Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, 20910, USA.
| | - Kawsar R Talaat
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Sandra D Isidean
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, 20910, USA
- Henry M. Jackson Foundation, Bethesda, MD, 20817, USA
| | - Alwine Kardinaal
- NIZO Food Research, Ede, P.O. Box 20, 6710 BA EDE, Kernhemseweg 2, 6718 ZB EDE, The Netherlands
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Ramiro L Gutiérrez
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, 20910, USA
| | - David A Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - A Louis Bourgeois
- PATH|Center for Vaccine Innovation and Access, 455 Massachusetts Avenue NW, Suite 1000, Washington, DC, 20001, USA
| |
Collapse
|
14
|
Liu MA, Kidambi A, Reeves PR. The low level of O antigen in Salmonella enterica Paratyphi A is due to inefficiency of the glycosyltransferase WbaV. FEMS Microbiol Lett 2021; 368:6105216. [PMID: 33476372 DOI: 10.1093/femsle/fnab009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/18/2021] [Indexed: 11/14/2022] Open
Abstract
The group A O antigen is the major surface polysaccharide of Salmonella enterica serovar Paratyphi A (SPA), and the focal point for most current vaccine development efforts. The SPA O-antigen repeat (O unit) is structurally similar to the group D1 O unit of S. enterica serovar Typhi, differing only in the presence of a terminal side-branch paratose (Par) in place of tyvelose (Tyv), both of which are attached by the glycosyltransferase WbaV. The two O-antigen gene clusters are also highly similar, but with a loss-of-function mutation in the group A tyv gene and the tandem amplification of wbaV in most SPA strains. In this study, we show that SPA strains consistently produce less O antigen than their group D1 counterparts and use an artificial group A strain (D1 Δtyv) to show this is due to inefficient Par attachment by WbaV. We also demonstrate that group A O-antigen production can be increased by overexpression of the wbaV gene in both the D1 Δtyv strain and two multi-wbaV SPA strains. These findings should be broadly applicable in ongoing vaccine development pipelines, where efficient isolation and purification of large quantities of O antigen is of critical importance.
Collapse
Affiliation(s)
- Michael A Liu
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Aditi Kidambi
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| | - Peter R Reeves
- School of Life and Environmental Sciences, The University of Sydney, NSW 2006, Australia
| |
Collapse
|