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Carboni F, Cozzi R, Romagnoli G, Tuscano G, Balocchi C, Buffi G, Bodini M, Brettoni C, Giusti F, Marchi S, Brogioni G, Brogioni B, Cinelli P, Cappelli L, Nocciolini C, Senesi S, Facciotti C, Frigimelica E, Fabbrini M, Stranges D, Savino S, Maione D, Adamo R, Wizel B, Margarit I, Romano MR. Proof of concept for a single-dose Group B Streptococcus vaccine based on capsular polysaccharide conjugated to Qβ virus-like particles. NPJ Vaccines 2023; 8:152. [PMID: 37803013 PMCID: PMC10558462 DOI: 10.1038/s41541-023-00744-5] [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: 06/23/2023] [Accepted: 09/15/2023] [Indexed: 10/08/2023] Open
Abstract
A maternal vaccine to protect neonates against Group B Streptococcus invasive infection is an unmet medical need. Such a vaccine should ideally be offered during the third trimester of pregnancy and induce strong immune responses after a single dose to maximize the time for placental transfer of protective antibodies. A key target antigen is the capsular polysaccharide, an anti-phagocytic virulence factor that elicits protective antibodies when conjugated to carrier proteins. The most prevalent polysaccharide serotypes conjugated to tetanus or diphtheria toxoids have been tested in humans as monovalent and multivalent formulations, showing excellent safety profiles and immunogenicity. However, responses were suboptimal in unprimed individuals after a single shot, the ideal schedule for vaccination during the third trimester of pregnancy. In the present study, we obtained and optimized self-assembling virus-like particles conjugated to Group B Streptococcus capsular polysaccharides. The resulting glyco-nanoparticles elicited strong immune responses in mice already after one immunization, providing pre-clinical proof of concept for a single-dose vaccine.
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Correlates of Protection for M Protein-Based Vaccines against Group A Streptococcus. J Immunol Res 2015; 2015:167089. [PMID: 26101780 PMCID: PMC4458553 DOI: 10.1155/2015/167089] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/28/2015] [Accepted: 05/03/2015] [Indexed: 11/17/2022] Open
Abstract
Group A streptococcus (GAS) is known to cause a broad spectrum of illness, from pharyngitis and impetigo, to autoimmune sequelae such as rheumatic heart disease, and invasive diseases. It is a significant cause of infectious disease morbidity and mortality worldwide, but no efficacious vaccine is currently available. Progress in GAS vaccine development has been hindered by a number of obstacles, including a lack of standardization in immunoassays and the need to define human correlates of protection. In this review, we have examined the current immunoassays used in both GAS and other organisms, and explored the various challenges in their implementation in order to propose potential future directions to identify a correlate of protection and facilitate the development of M protein-based vaccines, which are currently the main GAS vaccine candidates.
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Abstract
INTRODUCTION Globally, the three main pathogens causing serious infections are Haemophilus influenzae type b, Streptococcus pneumoniae and Neisseria meningitidis. Over the last 5 years, new vaccines protecting against these bacteria have been developed and introduced in various countries. AREAS COVERED This review describes the recently licensed glycoconjugates being used to protect against these encapsulated bacteria. Immunogenicity and safety data that led to licensure or licensure expansion of these glycoconjugates are discussed in addition to the resultant impact on the disease burden. EXPERT OPINION The maintenance of robust immunisation programmes with high uptake rates is important in maintaining low rates of disease. Epidemiological surveillance systems are essential in monitoring any changes in infectious disease trends and in identifying emerging infections such as from non-typeable H. influenzae, pneumococcal serotype replacement disease and changes in the epidemiology of meningococcal serogroups. This is important to guide future vaccine development. Accessibility of these glycoconjugate vaccines in resource poor regions, which bear the highest disease burden from these pathogens, remains challenging largely due to high vaccine pricing. Recent aids from public and private funding, tiered vaccine pricing and the transfer of vaccine technology have helped in introducing these vaccines where they are most needed.
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Affiliation(s)
- Mairi Vella
- Mater Dei Hospital, Department of Paediatrics , Tal-Qroqq, Msida, MSD 2090 , Malta +356 2545 5567 ; +356 2545 4154 ;
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Multilaboratory comparison of Streptococcus pneumoniae opsonophagocytic killing assays and their level of agreement for the determination of functional antibody activity in human reference sera. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 18:135-42. [PMID: 21084458 DOI: 10.1128/cvi.00370-10] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Antibody-mediated killing of Streptococcus pneumoniae (pneumococcus) by phagocytes is an important mechanism of protection of the human host against pneumococcal infections. Measurement of opsonophagocytic antibodies by use of a standardized opsonophagocytic assay (OPA) is important for the evaluation of candidate vaccines and required for the licensure of new pneumococcal conjugate vaccine formulations. We assessed agreement among six laboratories that used their own optimized OPAs on a panel of 16 human reference sera for 13 pneumococcal serotypes. Consensus titers, estimated using an analysis-of-variance (ANOVA) mixed-effects model, provided a common reference for assessing agreement among these laboratories. Agreement was evaluated in terms of assay accuracy, reproducibility, repeatability, precision, and bias. We also reviewed four acceptance criterion intervals for assessing the comparability of protocols when assaying the same reference sera. The precision, accuracy, and concordance results among laboratories and the consensus titers revealed acceptable agreement. The results of this study indicate that the bioassays evaluated in this study are robust, and the resultant OPA values are reproducible for the determination of functional antibody titers specific to 13 pneumococcal serotypes when performed by laboratories using highly standardized but not identical assays. The statistical methodologies employed in this study may serve as a template for evaluating future multilaboratory studies.
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Romero-Steiner S, Frasch CE, Carlone G, Fleck RA, Goldblatt D, Nahm MH. Use of opsonophagocytosis for serological evaluation of pneumococcal vaccines. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2006; 13:165-9. [PMID: 16467321 PMCID: PMC1391943 DOI: 10.1128/cvi.13.2.165-169.2006] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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