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Frost H, Excler JL, Sriskandan S, Fulurija A. Correlates of immunity to Group A Streptococcus: a pathway to vaccine development. NPJ Vaccines 2023; 8:1. [PMID: 36650164 PMCID: PMC9844947 DOI: 10.1038/s41541-022-00593-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 12/06/2022] [Indexed: 01/19/2023] Open
Abstract
Understanding immunity in humans to Group A Streptococcus (Strep A) is critical for the development of successful vaccines to prevent the morbidity and mortality attributed to Strep A infections. Despite decades of effort, no licensed vaccine against Strep A exists and immune correlates of protection are lacking; a major impediment to vaccine development. In the absence of a vaccine, we can take cues from the development of natural immunity to Strep A in humans to identify immune correlates of protection. The age stratification of incidence of acute Strep A infections, peaking in young children and waning in early adulthood, coincides with the development of specific immune responses. Therefore, understanding the immune mechanisms involved in natural protection from acute Strep A infection is critical to identifying immune correlates to inform vaccine development. This perspective summarises the findings from natural infection studies, existing assays of immunity to Strep A, and highlights the gaps in knowledge to guide the development of Strep A vaccines and associated correlates of protection.
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Affiliation(s)
- Hannah Frost
- grid.1058.c0000 0000 9442 535XMurdoch Children’s Research Institute, Melbourne, VIC Australia
| | - Jean-Louis Excler
- grid.30311.300000 0000 9629 885XInternational Vaccine Institute, Seoul, Republic of Korea
| | - Shiranee Sriskandan
- grid.7445.20000 0001 2113 8111Department of Infectious Disease, Imperial College London, London, UK ,grid.7445.20000 0001 2113 8111MRC Centre for Molecular Bacteriology & Infection, Imperial College London, London, UK
| | - Alma Fulurija
- grid.414659.b0000 0000 8828 1230Telethon Kid’s Institute, Perth, WA Australia ,grid.1012.20000 0004 1936 7910The University of Western Australia, Perth, WA Australia
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Abstract
PURPOSE OF REVIEW There is a global need for well tolerated, effective, and affordable vaccines to prevent group A streptococcal infections and their most serious complications. The aim of this review is to highlight the recent progress in the identification of promising vaccine antigens and new approaches to vaccine design that address the complexities of group A streptococcal pathogenesis and epidemiology. RECENT FINDINGS Combination vaccines containing multiple shared, cross-protective antigens have proven efficacious in mouse and nonhuman primate models of infection. The development of complex multivalent M protein-based vaccines is continuing and several have progressed through early-stage human clinical trials. Formulations of vaccines containing universal T-cell epitopes, toll-like receptor agonists, and other adjuvants more potent than alum have been shown to enhance protective immunogenicity. Although the group A streptococcal vaccine antigen landscape is populated with a number of potential candidates, the clinical development of vaccines has been impeded by a number of factors. There are now concerted global efforts to raise awareness about the need for group A streptococcal vaccines and to support progress toward eventual commercialization and licensure. SUMMARY Preclinical antigen discovery, vaccine formulation, and efficacy studies in animal models have progressed significantly in recent years. There is now a need to move promising candidates through the clinical development pathway to establish their efficacy in preventing group A streptococcal infections and their complications.
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Plasmid Replicons for the Production of Pharmaceutical-Grade pDNA, Proteins and Antigens by Lactococcus lactis Cell Factories. Int J Mol Sci 2021; 22:ijms22031379. [PMID: 33573129 PMCID: PMC7866527 DOI: 10.3390/ijms22031379] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/22/2021] [Accepted: 01/26/2021] [Indexed: 12/16/2022] Open
Abstract
The Lactococcus lactis bacterium found in different natural environments is traditionally associated with the fermented food industry. But recently, its applications have been spreading to the pharmaceutical industry, which has exploited its probiotic characteristics and is moving towards its use as cell factories for the production of added-value recombinant proteins and plasmid DNA (pDNA) for DNA vaccination, as a safer and industrially profitable alternative to the traditional Escherichia coli host. Additionally, due to its food-grade and generally recognized safe status, there have been an increasing number of studies about its use in live mucosal vaccination. In this review, we critically systematize the plasmid replicons available for the production of pharmaceutical-grade pDNA and recombinant proteins by L. lactis. A plasmid vector is an easily customized component when the goal is to engineer bacteria in order to produce a heterologous compound in industrially significant amounts, as an alternative to genomic DNA modifications. The additional burden to the cell depends on plasmid copy number and on the expression level, targeting location and type of protein expressed. For live mucosal vaccination applications, besides the presence of the necessary regulatory sequences, it is imperative that cells produce the antigen of interest in sufficient yields. The cell wall anchored antigens had shown more promising results in live mucosal vaccination studies, when compared with intracellular or secreted antigens. On the other side, engineering L. lactis to express membrane proteins, especially if they have a eukaryotic background, increases the overall cellular burden. The different alternative replicons for live mucosal vaccination, using L. lactis as the DNA vaccine carrier or the antigen producer, are critically reviewed, as a starting platform to choose or engineer the best vector for each application.
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García PC, Paillavil BA, Scioscia N, Dale JB, Legarraga P, Salazar-Echegarai FJ, Bueno SM, Kalergis AM, Wozniak A. Clinical and microbiological response of mice to intranasal inoculation with Lactococcus lactis expressing Group A Streptococcus antigens, to be used as an anti-streptococcal vaccine. Microbiol Immunol 2019; 62:711-719. [PMID: 30357922 DOI: 10.1111/1348-0421.12657] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/22/2018] [Accepted: 10/22/2018] [Indexed: 11/28/2022]
Abstract
Protein subunit vaccines are often preferred because of their protective efficacy and safety. Lactic acid bacteria expressing heterologous antigens constitute a promising approach to vaccine development. However, their safety in terms of toxicity and bacterial clearance must be evaluated. Anti-Streptococcus pyogenes (S. pyogenes) vaccines face additional safety concerns because they may elicit autoimmune responses. The assessment of toxicity, clearance and autoimmunity of an anti-streptococcal vaccine based on Lactococcus lactis (L. lactis) expressing 10 different M protein fragments from S. pyogenes (L. lactis-Mx10) is here reported. Clearance of L. lactis from the oropharynges of immunocompetent mice and mice devoid of T/B lymphocytes mice was achieved without using antibiotics. The absence of autoimmune responses against human tissues was demonstrated with human brain, heart and kidney. Assessment of toxicity showed that leucocyte counts and selected serum biochemical factors were not affected in L. lactis-Mx10-immunized mice. In contrast, mice immunized with L. lactis wild type vector (L. lactis-WT) showed increased neutrophil and monocyte counts and altered histopathology of lymph nodes, lungs and nasal epithelium. Two days after immunization, L. lactis-Mx10-immunized and L. lactis-WT-immunized mice weighed significantly less than unimmunized mice. However, both groups of immunized mice recovered their body weights by Day 6. Our results demonstrate that L. lactis-WT, but not the vaccine L. lactis-Mx10, induces alterations in certain hematologic and histopathological variables. We consider these data a major contribution to data on L. lactis as a bacterial vector for vaccine delivery.
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Affiliation(s)
- Patricia C García
- Laboratory of Microbiology, Department of Clinical Laboratories, School of Medicine, Pontifical Catholic University of Chile, Santiago 8331010, Chile
| | - Braulio A Paillavil
- Laboratory of Microbiology, Department of Clinical Laboratories, School of Medicine, Pontifical Catholic University of Chile, Santiago 8331010, Chile
| | - Natalia Scioscia
- Laboratory of Microbiology, Department of Clinical Laboratories, School of Medicine, Pontifical Catholic University of Chile, Santiago 8331010, Chile
| | - James B Dale
- Department of Medicine, University of Tennessee Health Science Center and the Department of Veterans Affairs Medical Center, Memphis, TN 38163, USA
| | - Paulette Legarraga
- Laboratory of Microbiology, Department of Clinical Laboratories, School of Medicine, Pontifical Catholic University of Chile, Santiago 8331010, Chile
| | - Francisco J Salazar-Echegarai
- Department of Molecular Genetics and Microbiology, School of Biological Sciences, Millennium Institute on Immunology and Immunotherapy, Pontifical Catholic University of Chile, Santiago 8331010, Chile
| | - Susan M Bueno
- Department of Molecular Genetics and Microbiology, School of Biological Sciences, Millennium Institute on Immunology and Immunotherapy, Pontifical Catholic University of Chile, Santiago 8331010, Chile
| | - Alexis M Kalergis
- Department of Molecular Genetics and Microbiology, School of Biological Sciences, Millennium Institute on Immunology and Immunotherapy, Pontifical Catholic University of Chile, Santiago 8331010, Chile.,Department of Endocrinology, School of Medicine, Pontifical Catholic University of Chile, Santiago 8331010, Chile
| | - Aniela Wozniak
- Laboratory of Microbiology, Department of Clinical Laboratories, School of Medicine, Pontifical Catholic University of Chile, Santiago 8331010, Chile.,Department of Endocrinology, School of Medicine, Pontifical Catholic University of Chile, Santiago 8331010, Chile
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