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Gasperini G, Massai L, De Simone D, Raso MM, Palmieri E, Alfini R, Rossi O, Ravenscroft N, Kuttel MM, Micoli F. O-Antigen decorations in Salmonella enterica play a key role in eliciting functional immune responses against heterologous serovars in animal models. Front Cell Infect Microbiol 2024; 14:1347813. [PMID: 38487353 PMCID: PMC10937413 DOI: 10.3389/fcimb.2024.1347813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 02/15/2024] [Indexed: 03/17/2024] Open
Abstract
Introduction Different serovars of Salmonella enterica cause systemic diseases in humans including enteric fever, caused by S. Typhi and S. Paratyphi A, and invasive nontyphoidal salmonellosis (iNTS), caused mainly by S. Typhimurium and S. Enteritidis. No vaccines are yet available against paratyphoid fever and iNTS but different strategies, based on the immunodominant O-Antigen component of the lipopolysaccharide, are currently being tested. The O-Antigens of S. enterica serovars share structural features including the backbone comprising mannose, rhamnose and galactose as well as further modifications such as O-acetylation and glucosylation. The importance of these O-Antigen decorations for the induced immunogenicity and cross-reactivity has been poorly characterized. Methods These immunological aspects were investigated in this study using Generalized Modules for Membrane Antigens (GMMA) as delivery systems for the different O-Antigen variants. This platform allowed the rapid generation and in vivo testing of defined and controlled polysaccharide structures through genetic manipulation of the O-Antigen biosynthetic genes. Results Results from mice and rabbit immunization experiments highlighted the important role played by secondary O-Antigen decorations in the induced immunogenicity. Moreover, molecular modeling of O-Antigen conformations corroborated the likelihood of cross-protection between S. enterica serovars. Discussion Such results, if confirmed in humans, could have a great impact on the design of a simplified vaccine composition able to maximize functional immune responses against clinically relevant Salmonella enterica serovars.
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Affiliation(s)
| | - Luisa Massai
- GSK Vaccines Institute for Global Health (GVGH), Siena, Italy
| | | | | | - Elena Palmieri
- GSK Vaccines Institute for Global Health (GVGH), Siena, Italy
| | - Renzo Alfini
- GSK Vaccines Institute for Global Health (GVGH), Siena, Italy
| | - Omar Rossi
- GSK Vaccines Institute for Global Health (GVGH), Siena, Italy
| | - Neil Ravenscroft
- Department of Chemistry, University of Cape Town, Rondebosch, South Africa
| | - Michelle M. Kuttel
- Department of Computer Science, University of Cape Town, Rondebosch, South Africa
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2
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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.
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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.
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Boero E, Vezzani G, Micoli F, Pizza M, Rossi O. Functional assays to evaluate antibody-mediated responses against Shigella: a review. Front Cell Infect Microbiol 2023; 13:1171213. [PMID: 37260708 PMCID: PMC10227456 DOI: 10.3389/fcimb.2023.1171213] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/27/2023] [Indexed: 06/02/2023] Open
Abstract
Shigella is a major global pathogen and the etiological agent of shigellosis, a diarrheal disease that primarily affects low- and middle-income countries. Shigellosis is characterized by a complex, multistep pathogenesis during which bacteria use multiple invasion proteins to manipulate and invade the intestinal epithelium. Antibodies, especially against the O-antigen and some invasion proteins, play a protective role as titres against specific antigens inversely correlate with disease severity; however, the context of antibody action during pathogenesis remains to be elucidated, especially with Shigella being mostly an intracellular pathogen. In the absence of a correlate of protection, functional assays rebuilding salient moments of Shigella pathogenesis can improve our understanding of the role of protective antibodies in blocking infection and disease. In vitro assays are important tools to build correlates of protection. Only recently animal models to recapitulate human pathogenesis, often not in full, have been established. This review aims to discuss in vitro assays to evaluate the functionality of anti-Shigella antibodies in polyclonal sera in light of the multistep and multifaced Shigella infection process. Indeed, measurement of antibody level alone may limit the evaluation of full vaccine potential. Serum bactericidal assay (SBA), and other functional assays such as opsonophagocytic killing assays (OPKA), and adhesion/invasion inhibition assays (AIA), are instead physiologically relevant and may provide important information regarding the role played by these effector mechanisms in protective immunity. Ultimately, the review aims at providing scientists in the field with new points of view regarding the significance of functional assays of choice which may be more representative of immune-mediated protection mechanisms.
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Affiliation(s)
- Elena Boero
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Siena, Italy
| | - Giacomo Vezzani
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Siena, Italy
| | - Francesca Micoli
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Siena, Italy
| | - Mariagrazia Pizza
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Siena, Italy
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Omar Rossi
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., Siena, Italy
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4
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Aruta MG, De Simone D, Dale H, Chirwa E, Kadwala I, Mbewe M, Banda H, Gordon M, Pizza M, Berlanda Scorza F, Nyirenda T, Canals R, Rossi O. Development and Characterization of a Luminescence-Based High-Throughput Serum Bactericidal Assay (L-SBA) to Assess Bactericidal Activity of Human Sera against Nontyphoidal Salmonella. Methods Protoc 2022; 5:100. [PMID: 36548142 PMCID: PMC9783057 DOI: 10.3390/mps5060100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/30/2022] [Accepted: 12/07/2022] [Indexed: 12/23/2022] Open
Abstract
Salmonella Typhimurium and Salmonella Enteritidis are leading causative agents of invasive nontyphoidal Salmonella (iNTS) disease, which represents one of the major causes of death and morbidity in sub-Saharan Africa, still partially underestimated. Large sero-epidemiological studies are necessary to unravel the burden of disease and guide the introduction of vaccines that are not yet available. Even if no correlate of protection has been determined so far for iNTS, the evaluation of complement-mediated functionality of antibodies generated towards natural infection or elicited upon vaccination may represent a big step towards this achievement. Here we present the setup and the intra-laboratory characterization in terms of repeatability, intermediate precision, linearity, and specificity of a high-throughput luminescence-based serum bactericidal assay (L-SBA). This method could be useful to perform sero-epidemiological studies across iNTS endemic countries and for evaluation of antibodies raised against iNTS vaccine candidates in upcoming clinical trials.
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Affiliation(s)
- Maria Grazia Aruta
- GSK Vaccines Institute for Global Health Srl, Via Fiorentina 1, 53100 Siena, Italy
| | - Daniele De Simone
- GSK Vaccines Institute for Global Health Srl, Via Fiorentina 1, 53100 Siena, Italy
| | - Helen Dale
- Malawi Liverpool Wellcome Trust Programme, Queen Elizabeth Central Hospital, College of Medicine, Blantyre 30096, Malawi
- Pathology Department, Kamuzu University of Health Sciences, Blantyre 312225, Malawi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Esmelda Chirwa
- Malawi Liverpool Wellcome Trust Programme, Queen Elizabeth Central Hospital, College of Medicine, Blantyre 30096, Malawi
- Pathology Department, Kamuzu University of Health Sciences, Blantyre 312225, Malawi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Innocent Kadwala
- Malawi Liverpool Wellcome Trust Programme, Queen Elizabeth Central Hospital, College of Medicine, Blantyre 30096, Malawi
- Pathology Department, Kamuzu University of Health Sciences, Blantyre 312225, Malawi
| | - Maurice Mbewe
- Malawi Liverpool Wellcome Trust Programme, Queen Elizabeth Central Hospital, College of Medicine, Blantyre 30096, Malawi
- Pathology Department, Kamuzu University of Health Sciences, Blantyre 312225, Malawi
| | - Happy Banda
- Malawi Liverpool Wellcome Trust Programme, Queen Elizabeth Central Hospital, College of Medicine, Blantyre 30096, Malawi
- Pathology Department, Kamuzu University of Health Sciences, Blantyre 312225, Malawi
| | - Melita Gordon
- Malawi Liverpool Wellcome Trust Programme, Queen Elizabeth Central Hospital, College of Medicine, Blantyre 30096, Malawi
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L69 3BX, UK
| | - Mariagrazia Pizza
- GSK Vaccines Institute for Global Health Srl, Via Fiorentina 1, 53100 Siena, Italy
| | | | - Tonney Nyirenda
- Pathology Department, Kamuzu University of Health Sciences, Blantyre 312225, Malawi
| | - Rocío Canals
- GSK Vaccines Institute for Global Health Srl, Via Fiorentina 1, 53100 Siena, Italy
| | - Omar Rossi
- GSK Vaccines Institute for Global Health Srl, Via Fiorentina 1, 53100 Siena, Italy
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5
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Mancini F, Micoli F, Rossi O. Setup and Characterization of a High-Throughput Luminescence-Based Serum Bactericidal Assay (L-SBA) to Determine Functionality of Human Sera against Shigella flexneri. BIOTECH 2022; 11:biotech11030029. [PMID: 35997337 PMCID: PMC9396978 DOI: 10.3390/biotech11030029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/19/2022] [Accepted: 07/25/2022] [Indexed: 12/02/2022] Open
Abstract
Shigellosis represents a major public health problem worldwide. The morbidity of the disease, especially in children in developing countries, together with the increase of antimicrobial resistance make a vaccine against Shigella an urgent medical need. Several vaccines under development are targeting Shigella lipopolysaccharide (LPS), whose extreme diversity renders necessary the development of multivalent vaccines. Immunity against Shigella LPS can elicit antibodies capable of killing bacteria in a serotype-specific manner. Therefore, although a correlation of protection against shigellosis has not been established, demonstration of vaccine-elicited antibody bactericidal activity may provide one means of vaccine protection against Shigella. To facilitate Shigella vaccine development, we have set up a high-throughput serum bactericidal assay based on luminescence readout (L-SBA), which has been already used to determine the functionality of antibodies against S. sonnei in multiple clinical trials. Here we present the setup and intra-laboratory characterization of L-SBA against three epidemiologically relevant Shigella flexneri serotypes using human sera. We assessed the linearity, repeatability and reproducibility of the method, demonstrating high assay specificity to detect the activity of antibodies against each homologous strain without any heterologous aspecificity against species-related and non-species-related strains; this assay is ready to be used to determine bactericidal activity of clinical sera raised by multivalent vaccines and in sero-epidemiological studies.
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Gasperini G, Raso MM, Schiavo F, Aruta MG, Ravenscroft N, Bellich B, Cescutti P, Necchi F, Rappuoli R, Micoli F. Rapid generation of Shigella flexneri GMMA displaying natural or new and cross-reactive O-Antigens. NPJ Vaccines 2022; 7:69. [PMID: 35773292 PMCID: PMC9243986 DOI: 10.1038/s41541-022-00497-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 05/16/2022] [Indexed: 11/09/2022] Open
Abstract
Generalized modules for membrane antigens (GMMA) are exosomes released from engineered Gram-negative bacteria and represent an attractive vaccine platform for the delivery of the O-Antigen (OAg), recognized as the key target for protective immunity against several pathogens such as Shigella. Shigella is a major cause of disease in Low- and Middle-Income countries and the development of a vaccine needs to deal with its large serotypic diversity. All S. flexneri serotypes, except serotype 6, share a conserved OAg backbone, corresponding to serotype Y. Here, a GMMA-producing S. flexneri scaffold strain displaying the OAg backbone was engineered with different OAg-modifying enzymes, either individually or in combinations. This strategy rapidly yielded GMMA displaying 12 natural serotypes and 16 novel serotypes expressing multiple epitopes combinations that do not occur in nature. Importantly, a candidate GMMA displaying a hybrid OAg elicited broadly cross-bactericidal antibodies against a large panel of S. flexneri serotypes.
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Affiliation(s)
| | - Maria Michelina Raso
- GSK Vaccines Institute for Global Health (GVGH), Siena, Italy.,Università di Trieste, Trieste, Italy
| | - Fabiola Schiavo
- GSK Vaccines Institute for Global Health (GVGH), Siena, Italy
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7
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Increasing the High Throughput of a Luminescence-Based Serum Bactericidal Assay (L-SBA). BIOTECH 2021; 10:biotech10030019. [PMID: 35822773 PMCID: PMC9245470 DOI: 10.3390/biotech10030019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/02/2021] [Accepted: 09/16/2021] [Indexed: 11/16/2022] Open
Abstract
Serum bactericidal assay (SBA) is the method to investigate in vitro complement-mediated bactericidal activity of sera raised upon vaccination. The assay is based on incubating the target bacteria and exogenous complement with sera at different dilutions and the result of the assay is represented by the sera dilution being able to kill 50% of bacteria present in the inoculum. The traditional readout of the assay is based on measurement of colony-forming units (CFU) obtained after plating different reaction mixes on agar. This readout is at low throughput and time consuming, even when automated counting is used. We previously described a novel assay with a luminescence readout (L-SBA) based on measurement of ATP released by live bacteria, which allowed to substantially increase the throughput as well as to reduce the time necessary to perform the assay when compared to traditional methods. Here we present a further improvement of the assay by moving from a 96-well to a 384-well format, which allowed us to further increase the throughput and substantially reduce costs while maintaining the high performance of the previously described L-SBA method. The method has been successfully applied to a variety of different pathogens.
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8
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Jones E, Jin C, Stockdale L, Dold C, Pollard AJ, Hill J. A Salmonella Typhi Controlled Human Infection Study for Assessing Correlation between Bactericidal Antibodies and Protection against Infection Induced by Typhoid Vaccination. Microorganisms 2021; 9:microorganisms9071394. [PMID: 34203328 PMCID: PMC8304662 DOI: 10.3390/microorganisms9071394] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/09/2021] [Accepted: 06/15/2021] [Indexed: 02/07/2023] Open
Abstract
Vi-polysaccharide conjugate vaccines are efficacious against typhoid fever in children living in endemic settings, their recent deployment is a promising step in the control of typhoid fever. However, there is currently no accepted correlate of protection. IgG and IgA antibodies generated in response to Vi conjugate or Vi plain polysaccharide vaccination are important but there are no definitive protective titre thresholds. We adapted a luminescence-based serum bactericidal activity (SBA) for use with S. Typhi and assessed whether bactericidal antibodies induced by either Vi tetanus toxoid conjugate (Vi-TT) or Vi plain polysaccharide (Vi-PS) were associated with protection in a controlled human infection model of typhoid fever. Both Vi-PS and Vi-TT induced significant increase in SBA titre after 28 days (Vi-PS; p < 0.0001, Vi-TT; p = 0.003), however higher SBA titre at the point of challenge did not correlate with protection from infection or reduced symptom severity. We cannot eliminate the role of SBA as part of a multifactorial immune response which protects against infection, however, our results do not support a strong role for SBA as a mechanism of Vi vaccine mediated protection in the CHIM setting.
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9
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Conformational and Immunogenicity Studies of the Shigella flexneri Serogroup 6 O-Antigen: The Effect of O-Acetylation. Vaccines (Basel) 2021; 9:vaccines9050432. [PMID: 33925465 PMCID: PMC8144980 DOI: 10.3390/vaccines9050432] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/21/2021] [Accepted: 04/21/2021] [Indexed: 01/30/2023] Open
Abstract
The pathogenic bacterium Shigella is a leading cause of diarrheal disease and mortality, disproportionately affecting young children in low-income countries. The increasing prevalence of antibiotic resistance in Shigella necessitates an effective vaccine, for which the bacterial lipopolysaccharide O-antigen is the primary target. S. flexneri serotype 6 has been proposed as a multivalent vaccine component to ensure broad protection against Shigella. We have previously explored the conformations of S. flexneri O-antigens from serogroups Y, 2, 3, and 5 that share a common saccharide backbone (serotype Y). Here we consider serogroup 6, which is of particular interest because of an altered backbone repeat unit with non-stoichiometric O-acetylation, the antigenic and immunogenic importance of which have yet to be established. Our simulations show significant conformational changes in serogroup 6 relative to the serotype Y backbone. We further find that O-acetylation has little effect on conformation and hence may not be essential for the antigenicity of serotype 6. This is corroborated by an in vivo study in mice, using Generalized Modules for Membrane Antigens (GMMA) as O-antigen delivery systems, that shows that O-acetylation does not have an impact on the immune response elicited by the S. flexneri serotype 6 O-antigen.
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Salmonella Paratyphi A Outer Membrane Vesicles Displaying Vi Polysaccharide as a Multivalent Vaccine against Enteric Fever. Infect Immun 2021; 89:IAI.00699-20. [PMID: 33318138 DOI: 10.1128/iai.00699-20] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 12/07/2020] [Indexed: 12/23/2022] Open
Abstract
Typhoid and paratyphoid fevers have a high incidence worldwide and coexist in many geographical areas, especially in low-middle-income countries (LMIC) in South and Southeast Asia. There is extensive consensus on the urgent need for better and affordable vaccines against systemic Salmonella infections. Generalized modules for membrane antigens (GMMA), outer membrane exosomes shed by Salmonella bacteria genetically manipulated to increase blebbing, resemble the bacterial surface where protective antigens are displayed in their native environment. Here, we engineered S Paratyphi A using the pDC5-viaB plasmid to generate GMMA displaying the heterologous S Typhi Vi antigen together with the homologous O:2 O antigen. The presence of both Vi and O:2 was confirmed by flow cytometry on bacterial cells, and their amount was quantified on the resulting vesicles through a panel of analytical methods. When tested in mice, such GMMA induced a strong antibody response against both Vi and O:2, and these antibodies were functional in a serum bactericidal assay. Our approach yielded a bivalent vaccine candidate able to induce immune responses against different Salmonella serovars, which could benefit LMIC residents and travelers.
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11
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Mancini F, Gasperini G, Rossi O, Aruta MG, Raso MM, Alfini R, Biagini M, Necchi F, Micoli F. Dissecting the contribution of O-Antigen and proteins to the immunogenicity of Shigella sonnei generalized modules for membrane antigens (GMMA). Sci Rep 2021; 11:906. [PMID: 33441861 PMCID: PMC7806729 DOI: 10.1038/s41598-020-80421-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 12/11/2020] [Indexed: 01/11/2023] Open
Abstract
GMMA are exosomes released from engineered Gram-negative bacteria resembling the composition of outer membranes. We applied the GMMA technology for the development of an O-Antigen (OAg) based vaccine against Shigella sonnei, the most epidemiologically relevant cause of shigellosis. S. sonnei OAg has been identified as a key antigen for protective immunity, and GMMA are able to induce anti-OAg-specific IgG response in animal models and healthy adults. The contribution of protein-specific antibodies induced upon vaccination with GMMA has never been fully elucidated. Anti-protein antibodies are induced in mice upon immunization with either OAg-negative and OAg-positive GMMA. Here we demonstrated that OAg chains shield the bacteria from anti-protein antibody binding and therefore anti-OAg antibodies were the main drivers of bactericidal activity against OAg-positive bacteria. Interestingly, antibodies that are not targeting the OAg are functional against OAg-negative bacteria. The immunodominant protein antigens were identified by proteomic analysis. Our study confirms a critical role of the OAg on the immune response induced by S. sonnei GMMA. However, little is known about OAg length and density regulation during infection and, therefore, protein exposure. Hence, the presence of protein antigens on S. sonnei GMMA represents an added value for GMMA vaccines compared to other OAg-based formulations.
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Affiliation(s)
- Francesca Mancini
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Gianmarco Gasperini
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Omar Rossi
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Maria Grazia Aruta
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Maria Michelina Raso
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Renzo Alfini
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | | | - Francesca Necchi
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy
| | - Francesca Micoli
- GSK Vaccines Institute for Global Health (GVGH), via Fiorentina 1, 53100, Siena, Italy.
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12
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Micoli F, Alfini R, Di Benedetto R, Necchi F, Schiavo F, Mancini F, Carducci M, Palmieri E, Balocchi C, Gasperini G, Brunelli B, Costantino P, Adamo R, Piccioli D, Saul A. GMMA Is a Versatile Platform to Design Effective Multivalent Combination Vaccines. Vaccines (Basel) 2020; 8:E540. [PMID: 32957610 PMCID: PMC7564227 DOI: 10.3390/vaccines8030540] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/12/2020] [Accepted: 09/14/2020] [Indexed: 01/21/2023] Open
Abstract
Technology platforms are an important strategy to facilitate the design, development and implementation of vaccines to combat high-burden diseases that are still a threat for human populations, especially in low- and middle-income countries, and to address the increasing number and global distribution of pathogens resistant to antimicrobial drugs. Generalized Modules for Membrane Antigens (GMMA), outer membrane vesicles derived from engineered Gram-negative bacteria, represent an attractive technology to design affordable vaccines. Here, we show that GMMA, decorated with heterologous polysaccharide or protein antigens, leads to a strong and effective antigen-specific humoral immune response in mice. Importantly, GMMA promote enhanced immunogenicity compared to traditional formulations (e.g., recombinant proteins and glycoconjugate vaccines), without negative impact to the anti-GMMA immune response. Our findings support the use of GMMA as a "plug and play" technology for the development of effective combination vaccines targeting different bugs at the same time.
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Affiliation(s)
- Francesca Micoli
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | - Renzo Alfini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | - Roberta Di Benedetto
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | - Francesca Necchi
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | - Fabiola Schiavo
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | - Francesca Mancini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | - Martina Carducci
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | - Elena Palmieri
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | | | - Gianmarco Gasperini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
| | | | | | - Roberto Adamo
- GSK, 53100 Siena, Italy; (C.B.); (B.B.); (P.C.); (R.A.); (D.P.)
| | - Diego Piccioli
- GSK, 53100 Siena, Italy; (C.B.); (B.B.); (P.C.); (R.A.); (D.P.)
| | - Allan Saul
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., 53100 Siena, Italy; (R.A.); (R.D.B.); (F.N.); (F.S.); (F.M.); (M.C.); (E.P.); (G.G.); (A.S.)
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13
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Intra-Laboratory Evaluation of Luminescence Based High-Throughput Serum Bactericidal Assay (L-SBA) to Determine Bactericidal Activity of Human Sera against Shigella. High Throughput 2020; 9:ht9020014. [PMID: 32521658 PMCID: PMC7361673 DOI: 10.3390/ht9020014] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/01/2020] [Accepted: 06/04/2020] [Indexed: 12/31/2022] Open
Abstract
Despite the huge decrease in deaths caused by Shigella worldwide in recent decades, shigellosis still causes over 200,000 deaths every year. No vaccine is currently available, and the morbidity of the disease coupled with the rise of antimicrobial resistance renders the introduction of an effective vaccine extremely urgent. Although a clear immune correlate of protection against shigellosis has not yet been established, the demonstration of the bactericidal activity of antibodies induced upon vaccination may provide one means of the functionality of antibodies induced in protecting against Shigella. The method of choice to evaluate the complement-mediated functional activity of vaccine-induced antibodies is the Serum Bactericidal Assay (SBA). Here we present the development and intra-laboratory characterization of a high-throughput luminescence-based SBA (L-SBA) method, based on the detection of ATP as a proxy of surviving bacteria, to evaluate the complement-mediated killing of human sera. We demonstrated the high specificity of the assay against a homologous strain without any heterologous aspecificity detected against species-related and non-species-related strains. We assessed the linearity, repeatability and reproducibility of L-SBA on human sera. This work will guide the bactericidal activity assessment of clinical sera raised against S. sonnei. The method has the potential of being applicable with similar performances to determine the bactericidal activity of any non-clinical and clinical sera that rely on complement-mediated killing.
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14
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Raso MM, Gasperini G, Alfini R, Schiavo F, Aruta MG, Carducci M, Forgione MC, Martini S, Cescutti P, Necchi F, Micoli F. GMMA and Glycoconjugate Approaches Compared in Mice for the Development of a Vaccine against Shigella flexneri Serotype 6. Vaccines (Basel) 2020; 8:vaccines8020160. [PMID: 32260067 PMCID: PMC7349896 DOI: 10.3390/vaccines8020160] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/30/2020] [Accepted: 04/02/2020] [Indexed: 12/12/2022] Open
Abstract
Shigella infections are one of the top causes of diarrhea throughout the world, with Shigella flexneri being predominant in developing countries. Currently, no vaccines are widely available and increasing levels of multidrug-resistance make Shigella a high priority for vaccine development. The serotype-specific O-antigen moiety of Shigella lipopolysaccharide has been recognized as a key target for protective immunity, and many O-antigen based candidate vaccines are in development. Recently, the Generalized Modules for Membrane Antigens (GMMA) technology has been proposed as an alternative approach to traditional glycoconjugate vaccines for O-antigen delivery. Here, these two technologies are compared for a vaccine against S. flexneri serotype 6. Genetic strategies for GMMA production, conjugation approaches for linkage of the O-antigen to CRM197 carrier protein, and a large panel of analytical methods for full vaccine characterization have been put in place. In a head-to-head immunogenicity study in mice, GMMA induced higher anti-O-antigen IgG than glycoconjugate administered without Alhydrogel. When formulated on Alhydrogel, GMMA and glycoconjugate elicited similar levels of persistent anti-O-antigen IgG with bactericidal activity. Glycoconjugates are a well-established bacterial vaccine approach, but can be costly, particularly when multicomponent preparations are required. With similar immunogenicity and a simpler manufacturing process, GMMA are a promising strategy for the development of a vaccine against Shigella.
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Affiliation(s)
- Maria Michelina Raso
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy; (M.M.R.); (G.G.); (R.A.); (F.S.); (M.G.A.); (M.C.); (F.N.)
- Department of Life Science, University of Trieste, Building C11, via L. Giorgieri 1, 34127 Trieste, Italy;
| | - Gianmarco Gasperini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy; (M.M.R.); (G.G.); (R.A.); (F.S.); (M.G.A.); (M.C.); (F.N.)
| | - Renzo Alfini
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy; (M.M.R.); (G.G.); (R.A.); (F.S.); (M.G.A.); (M.C.); (F.N.)
| | - Fabiola Schiavo
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy; (M.M.R.); (G.G.); (R.A.); (F.S.); (M.G.A.); (M.C.); (F.N.)
| | - Maria Grazia Aruta
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy; (M.M.R.); (G.G.); (R.A.); (F.S.); (M.G.A.); (M.C.); (F.N.)
| | - Martina Carducci
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy; (M.M.R.); (G.G.); (R.A.); (F.S.); (M.G.A.); (M.C.); (F.N.)
| | | | - Silvia Martini
- GSK, via Fiorentina 1, 53100 Siena, Italy; (M.C.F.); (S.M.)
| | - Paola Cescutti
- Department of Life Science, University of Trieste, Building C11, via L. Giorgieri 1, 34127 Trieste, Italy;
| | - Francesca Necchi
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy; (M.M.R.); (G.G.); (R.A.); (F.S.); (M.G.A.); (M.C.); (F.N.)
| | - Francesca Micoli
- GSK Vaccines Institute for Global Health (GVGH) S.r.l., via Fiorentina 1, 53100 Siena, Italy; (M.M.R.); (G.G.); (R.A.); (F.S.); (M.G.A.); (M.C.); (F.N.)
- Correspondence: ; Tel.: +39-0577-539087
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15
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Clow F, O’Hanlon CJ, Christodoulides M, Radcliff FJ. Feasibility of Using a Luminescence-Based Method to Determine Serum Bactericidal Activity against Neisseria gonorrhoeae. Vaccines (Basel) 2019; 7:vaccines7040191. [PMID: 31766474 PMCID: PMC6963289 DOI: 10.3390/vaccines7040191] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/12/2019] [Accepted: 11/19/2019] [Indexed: 01/15/2023] Open
Abstract
Development of a vaccine to limit the impact of antibiotic resistant Neisseria gonorrhoeae is now a global priority. Serum bactericidal antibody (SBA) is a possible indicator of protective immunity to N. gonorrhoeae, but conventional assays measure colony forming units (CFU), which is time-consuming. A luminescent assay that quantifies ATP as a surrogate measure of bacterial viability was tested on N. gonorrhoeae strains FA1090, MS11 and P9-17 and compared to CFU-based readouts. There was a linear relationship between CFU and ATP levels for all three strains (r > 0.9). Normal human serum (NHS) is a common source of complement for SBA assays, but needs to be screened for non-specific bactericidal activity. NHS from 10 individuals were used for serum sensitivity assays-sensitivity values were significantly reduced with the ATP method for FA1090 (5/10, p < 0.05) and MS11 (10/10, p < 0.05), whereas P9-17 data were comparable for all donors. Our results suggest that measuring ATP underestimates serum sensitivity of N. gonorrhoeae and that the CFU method is a better approach. However, mouse anti-P9-17 outer membrane vesicles (OMV) SBA titres to P9-17 were comparable with both methods (r = 0.97), suggesting this assay can be used to rapidly screen sera for bactericidal antibodies to gonococci.
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Affiliation(s)
- Fiona Clow
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand; (F.C.); (C.J.O.)
| | - Conor J O’Hanlon
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand; (F.C.); (C.J.O.)
| | - Myron Christodoulides
- Faculty of Medicine, Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton, Southampton SO166YD, UK;
| | - Fiona J Radcliff
- Department of Molecular Medicine and Pathology, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1023, New Zealand; (F.C.); (C.J.O.)
- Correspondence: ; Tel.: +64-9923-6272
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