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Martin LB, Tack B, Marchello CS, Sikorski MJ, Owusu-Dabo E, Nyirenda T, Mogasale V, Crump JA. Vaccine value profile for invasive non-typhoidal Salmonella disease. Vaccine 2024; 42:S101-S124. [PMID: 39003017 DOI: 10.1016/j.vaccine.2024.04.045] [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: 04/12/2024] [Accepted: 04/14/2024] [Indexed: 07/15/2024]
Abstract
Invasive non-typhoidal Salmonella (iNTS) disease is an under-recognized high-burden disease causing major health and socioeconomic issues in sub-Saharan Africa (sSA), predominantly among immune-naïve infants and young children, including those with recognized comorbidities such as HIV infection. iNTS disease is primarily caused by Salmonella enterica serovar Typhimurium sequence type (ST) 313 and 'African-restricted clades' of Salmonella Enteritidis ST11 that have emerged across the African continent as a series of epidemics associated with acquisition of new antimicrobial resistance. Due to genotypes with a high prevalence of antimicrobial resistance and scarcity of therapeutic options, these NTS serovars are designated by the World Health Organization as a priority pathogen for research and development of interventions, including vaccines, to address and reduce NTS associated bacteremia and meningitis in sSA. Novel and traditional vaccine technologies are being applied to develop vaccines against iNTS disease, and the results of the first clinical trials in the infant target population should become available in the near future. The "Vaccine Value Profile" (VVP) addresses information related predominantly to invasive disease caused by Salmonella Enteritidis and Salmonella Typhimurium prevalent in sSA. Information is included on stand-alone iNTS disease candidate vaccines and candidate vaccines targeting iNTS disease combined with another invasive serotype, Salmonella Typhi, that is also common across sSA. Out of scope for the first version of this VVP is a wider discussion on either diarrheagenic NTS disease (dNTS) also associated with Salmonella Enteritidis and Salmonella Typhimurium or the development of a multivalent Salmonella vaccines targeting key serovars for use globally. This VVP for vaccines to prevent iNTS disease is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic, and societal value of pipeline vaccines and vaccine-like products. Future versions of this VVP will be updated to reflect ongoing activities such as vaccine development strategies and a "Full Vaccine Value Assessment" that will inform the value proposition of an iNTS disease vaccine. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships, and multi-lateral organizations, and in collaboration with stakeholders from the World Health Organization African Region. All contributors have extensive expertise on various elements of the iNTS disease VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.
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Affiliation(s)
| | - Bieke Tack
- Department of Clinical Sciences, Institute of Tropical Medicine Antwerp, Belgium and Department of Microbiology, Immunology and Transplantation, KU Leuven, Belgium.
| | | | - Michael J Sikorski
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
| | | | | | | | - John A Crump
- Centre for International Health, University of Otago, New Zealand.
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History of Human Challenge Studies. HUMAN CHALLENGE STUDIES IN ENDEMIC SETTINGS 2021. [PMCID: PMC7431914 DOI: 10.1007/978-3-030-41480-1_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The intentional infection of human beings with pathogens with the aim of achieving benefits (chiefly, the prevention of more severe disease) has occurred for centuries; the (semi-)systematic testing and recording of such methods dates to the 18th Century in England.
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Phoba MF, Barbé B, Ley B, Van Puyvelde S, Post A, Mattheus W, Deborggraeve S, Lunguya O, Jacobs J. High genetic similarity between non-typhoidal Salmonella isolated from paired blood and stool samples of children in the Democratic Republic of the Congo. PLoS Negl Trop Dis 2020; 14:e0008377. [PMID: 32614856 PMCID: PMC7331982 DOI: 10.1371/journal.pntd.0008377] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 05/08/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Non-typhoidal Salmonella (NTS) serotypes Typhimurium and Enteritidis are a major cause of bloodstream infections in children in sub-Saharan Africa but their reservoir is unknown. We compared pairs of NTS blood and stool isolates (with the same NTS serotype recovered in the same patient) for genetic similarity. METHODS Between November 2013 and April 2017, hospital-admitted children (29 days to 14 years) with culture-confirmed NTS bloodstream infections were enrolled in a cross-sectional study at Kisantu Hospital, DR Congo. Stool cultures for Salmonella were performed on a subset of enrolled children, as well as on a control group of non-febrile hospital-admitted children. Pairs of blood and stool NTS isolates were assessed for genetic similarity by multiple-locus variable-number of tandem repeats (MLVA) and genomics analysis. RESULTS A total of 299 children with NTS grown from blood cultures (Typhimurium 68.6%, Enteritidis 30.4%, other NTS 1.0%) had a stool sample processed; in 105 (35.1%) of them NTS was detected (Typhimurium 70.5%, Enteritidis 25.7%, other NTS 3.8%). A total of 87/105 (82.9%) pairs of blood and stool NTS isolates were observed (representing 29.1% of the 299 children). Among 1598 controls, the proportion of NTS stool excretion was 2.1% (p < 0.0001). MLVA types among paired isolates were identical in 82/87 (94.3%) pairs (27.4% of the 299 children; 61/66 (92.4%) in Typhimurium and 21/21 (100%) in Enteritidis pairs). Genomics analysis confirmed high genetic similarity within 41/43 (95.3%) pairs, showing a median SNP difference of 1 (range 0-77) and 1 (range 0-4) for Typhimurium and Enteritidis pairs respectively. Typhimurium and Enteritidis isolates belonged to sequence types ST313 lineage II and ST11 respectively. CONCLUSION Nearly 30% of children with NTS bloodstream infection showed stool excretion of an NTS isolate with high genetic similarity, adding to the evidence of humans as a potential reservoir for NTS.
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Affiliation(s)
- Marie-France Phoba
- Department of Microbiology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo
- Department of Microbiology, University Hospital of Kinshasa, Democratic Republic of the Congo
| | - Barbara Barbé
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Benedikt Ley
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Sandra Van Puyvelde
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Annelies Post
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Wesley Mattheus
- Department of Human Bacterial Diseases, Sciensano, Brussels, Belgium
| | - Stijn Deborggraeve
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Octavie Lunguya
- Department of Microbiology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo
- Department of Microbiology, University Hospital of Kinshasa, Democratic Republic of the Congo
| | - Jan Jacobs
- Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- Department of Microbiology, Immunology and Transplantation, KU Leuven, Leuven, Belgium
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Raymond M, Gibani MM, Day NPJ, Cheah PY. Typhoidal Salmonella human challenge studies: ethical and practical challenges and considerations for low-resource settings. Trials 2019; 20:704. [PMID: 31852488 PMCID: PMC6921376 DOI: 10.1186/s13063-019-3844-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Typhoidal Salmonella is a major global problem affecting more than 12 million people annually. Controlled human infection models (CHIMs) in high-resource settings have had an important role in accelerating the development of conjugate vaccines against Salmonella Typhi. The typhoidal Salmonella model has an established safety profile in over 2000 volunteers in high-income settings, and trial protocols, with modification, could be readily transferred to new study sites. To date, a typhoidal Salmonella CHIM has not been conducted in a low-resource setting, although it is being considered. Our article describes the challenges posed by a typhoidal Salmonella CHIM in the high-resource setting of Oxford and explores considerations for an endemic setting. Development of CHIMs in endemic settings is scientifically justifiable as it remains unclear whether findings from challenge studies performed in high-resource non-endemic settings can be extrapolated to endemic settings, where the burden of invasive Salmonella is highest. Volunteers are likely to differ across a range of important variables such as previous Salmonella exposure, diet, intestinal microbiota, and genetic profile. CHIMs in endemic settings arguably are ethically justifiable as affected communities are more likely to gain benefit from the study. Local training and research capacity may be bolstered. Safety was of primary importance in the Oxford model. Risk of harm to the individual was mitigated by careful inclusion and exclusion criteria; close monitoring with online diary and daily visits; 24/7 on-call staffing; and access to appropriate hospital facilities with capacity for in-patient admission. Risk of harm to the community was mitigated by exclusion of participants with contact with vulnerable persons; stringent hygiene and sanitation precautions; and demonstration of clearance of Salmonella infection from stool following antibiotic treatment. Safety measures should be more stringent in settings where health systems, transport networks, and sanitation are less robust. We compare the following issues between high- and low-resource settings: scientific justification, risk of harm to the individual and community, benefits to the individual and community, participant understanding, compensation, and regulatory requirements. We conclude that, with careful consideration of country-specific ethical and practical issues, a typhoidal Salmonella CHIM in an endemic setting is possible.
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Affiliation(s)
- Meriel Raymond
- Oxford Vaccine Group Centre for Clinical Vaccinology and Tropical Medicine (CCVTM), Churchill Hospital, Old Road, Headington, Oxford, OX3 7LE, UK
| | - Malick M Gibani
- Oxford Vaccine Group Centre for Clinical Vaccinology and Tropical Medicine (CCVTM), Churchill Hospital, Old Road, Headington, Oxford, OX3 7LE, UK
| | - Nicholas P J Day
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand.,Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Phaik Yeong Cheah
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand. .,Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK. .,Nuffield Departmemt of Population Health, The Ethox Centere, University of Oxford, Old Road, Oxford, OX3 7LF, UK.
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Awofisayo-Okuyelu A, Pratt A, McCarthy N, Hall I. Within-host mathematical modelling of the incubation period of Salmonella Typhi. ROYAL SOCIETY OPEN SCIENCE 2019; 6:182143. [PMID: 31598273 PMCID: PMC6774937 DOI: 10.1098/rsos.182143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
Mechanistic mathematical models are often employed to understand the dynamics of infectious diseases within a population or within a host. They provide estimates that may not be otherwise available. We have developed a within-host mathematical model in order to understand how the pathophysiology of Salmonella Typhi contributes to its incubation period. The model describes the process of infection from ingestion to the onset of clinical illness using a set of ordinary differential equations. The model was parametrized using estimated values from human and mouse experimental studies and the incubation period was estimated as 9.6 days. A sensitivity analysis was also conducted to identify the parameters that most affect the derived incubation period. The migration of bacteria to the caecal lymph node was observed as a major bottle neck for infection. The sensitivity analysis indicated the growth rate of bacteria in late phase systemic infection and the net population of bacteria in the colon as parameters that most influence the incubation period. We have shown in this study how mathematical models aid in the understanding of biological processes and can be used in estimating parameters of infectious diseases.
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Affiliation(s)
- Adedoyin Awofisayo-Okuyelu
- National Institute of Health Research Health Protection Research Unit in Gastrointestinal Infections, University of Oxford, Oxford, UK
- Department of Zoology, University of Oxford, Oxford, UK
| | - Adrian Pratt
- Emergency Response Department Science and Technology (ERD S&T), Health Protection Directorate, Public Health England, Porton Down, UK
| | - Noel McCarthy
- National Institute of Health Research Health Protection Research Unit in Gastrointestinal Infections, University of Oxford, Oxford, UK
- Department of Zoology, University of Oxford, Oxford, UK
- Warwick Medical School, University of Warwick, Coventry, UK
| | - Ian Hall
- School of Mathematics, University of Manchester, Manchester, UK
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Juel HB, Thomaides-Brears HB, Darton TC, Jones C, Jones E, Shrestha S, Sie R, Eustace A, Galal U, Kurupati P, Van TT, Thieu NTV, Baker S, Blohmke CJ, Pollard AJ. Salmonella Typhi Bactericidal Antibodies Reduce Disease Severity but Do Not Protect against Typhoid Fever in a Controlled Human Infection Model. Front Immunol 2018; 8:1916. [PMID: 29387052 PMCID: PMC5776093 DOI: 10.3389/fimmu.2017.01916] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 12/14/2017] [Indexed: 01/12/2023] Open
Abstract
Effective vaccines against Salmonella Typhi, a major cause of febrile illness in tropical regions, can have a significant effect as a disease control measure. Earlier work has shown that immunization with either of two Salmonella Typhi vaccines, licensed Ty21a or candidate M01ZH09, did not provide full immunity in a controlled human infection model. Here, we describe the human humoral immune responses to these oral vaccines and their functional role in protection after challenge with S. Typhi. Serum, obtained from healthy volunteers before and after vaccination with Ty21a or M01ZH09 or placebo and before and after oral challenge with wild-type S. Typhi, was assessed for bactericidal activity. Single-dose vaccination with M01ZH09 induced an increase in serum bactericidal antibodies (p = 0.001) while three doses of Ty21a did not. No association between bactericidal activity and protection against typhoid after challenge was seen in either vaccine arm. Bactericidal activity after vaccination correlated significantly with delayed disease onset (p = 0.013), lower bacterial burden (p = 0.006), and decreased disease severity scores (p = 0.021). Depletion of antibodies directed against lipopolysaccharide significantly reduced bactericidal activity (p = 0.009). We conclude that antibodies induced after ingestion of oral live-attenuated typhoid vaccines or after challenge with wild-type S. Typhi exhibit bactericidal activity. This bactericidal activity is mediated by anti-O:LPS antibodies and significantly reduces clinical symptoms but does not provide sterile immunity. This directs future vaccine studies toward other antigens or mechanisms of protection against typhoid.
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Affiliation(s)
- Helene B Juel
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.,Statens Serum Institut, Copenhagen, Denmark
| | - Helena B Thomaides-Brears
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Thomas C Darton
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.,Department of Infection, Immunity and Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Claire Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Elizabeth Jones
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Sonu Shrestha
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Rebecca Sie
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Andrew Eustace
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Ushma Galal
- Nuffield Department of Primary Care Health Sciences, Clinical Trials Unit, University of Oxford, Oxford, United Kingdom
| | - Prathiba Kurupati
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Tan T Van
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Nga T V Thieu
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam
| | - Stephen Baker
- The Hospital for Tropical Diseases, Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.,The Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Christoph J Blohmke
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, The NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
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Gordon SB, Rylance J, Luck A, Jambo K, Ferreira DM, Manda-Taylor L, Bejon P, Ngwira B, Littler K, Seager Z, Gibani M, Gmeiner M, Roestenberg M, Mlombe Y. A framework for Controlled Human Infection Model (CHIM) studies in Malawi: Report of a Wellcome Trust workshop on CHIM in Low Income Countries held in Blantyre, Malawi. Wellcome Open Res 2017; 2:70. [PMID: 29018841 PMCID: PMC5627502 DOI: 10.12688/wellcomeopenres.12256.1] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2017] [Indexed: 11/29/2022] Open
Abstract
Controlled human infection model (CHIM) studies have pivotal importance in vaccine development, being useful for proof of concept, pathogenesis, down-selection and immunogenicity studies. To date, however, they have seldom been carried out in low and middle income countries (LMIC), which is where the greatest burden of vaccine preventable illness is found. This workshop discussed the benefits and barriers to CHIM studies in Malawi. Benefits include improved vaccine effectiveness and host country capacity development in clinical, laboratory and governance domains. Barriers include acceptability, safety and regulatory issues. The report suggests a framework by which ethical, laboratory, scientific and governance issues may be addressed by investigators considering or planning CHIM in LMIC.
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Affiliation(s)
- Stephen B Gordon
- The Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Jamie Rylance
- The Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Amy Luck
- Vaccines, Wellcome Trust, London, NW1 2BE, UK
| | - Kondwani Jambo
- The Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | | | | | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Zoe Seager
- Vaccines, Wellcome Trust, London, NW1 2BE, UK
| | - Malick Gibani
- Oxford Vaccines Group, Department of Paediatrics, Children's Hospital, Oxford, OX3 9DU, UK
| | - Markus Gmeiner
- The Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | | | - Yohannie Mlombe
- College of Medicine Research Ethics Committee, John Chiphangwi Learning Resource Centre, Blantyre, Malawi
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