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Xing Y, Clark JR, Chang JD, Zulk JJ, Chirman DM, Piedra FA, Vaughan EE, Hernandez Santos HJ, Patras KA, Maresso AW. Progress toward a vaccine for extraintestinal pathogenic E. coli (ExPEC) II: efficacy of a toxin-autotransporter dual antigen approach. Infect Immun 2024; 92:e0044023. [PMID: 38591882 DOI: 10.1128/iai.00440-23] [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: 11/01/2023] [Accepted: 03/18/2024] [Indexed: 04/10/2024] Open
Abstract
Extraintestinal pathogenic Escherichia coli (ExPEC) is a leading cause of worldwide morbidity and mortality, the top cause of antimicrobial-resistant (AMR) infections, and the most frequent cause of life-threatening sepsis and urinary tract infections (UTI) in adults. The development of an effective and universal vaccine is complicated by this pathogen's pan-genome, its ability to mix and match virulence factors and AMR genes via horizontal gene transfer, an inability to decipher commensal from pathogens, and its intimate association and co-evolution with mammals. Using a pan virulome analysis of >20,000 sequenced E. coli strains, we identified the secreted cytolysin α-hemolysin (HlyA) as a high priority target for vaccine exploration studies. We demonstrate that a catalytically inactive pure form of HlyA, expressed in an autologous host using its own secretion system, is highly immunogenic in a murine host, protects against several forms of ExPEC infection (including lethal bacteremia), and significantly lowers bacterial burdens in multiple organ systems. Interestingly, the combination of a previously reported autotransporter (SinH) with HlyA was notably effective, inducing near complete protection against lethal challenge, including commonly used infection strains ST73 (CFT073) and ST95 (UTI89), as well as a mixture of 10 of the most highly virulent sequence types and strains from our clinical collection. Both HlyA and HlyA-SinH combinations also afforded some protection against UTI89 colonization in a murine UTI model. These findings suggest recombinant, inactive hemolysin and/or its combination with SinH warrant investigation in the development of an E. coli vaccine against invasive disease.
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Affiliation(s)
- Yikun Xing
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- TAILOR Labs, Vaccine Development Group, Baylor College of Medicine, Houston, Texas, USA
| | - Justin R Clark
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- TAILOR Labs, Vaccine Development Group, Baylor College of Medicine, Houston, Texas, USA
| | - James D Chang
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- TAILOR Labs, Vaccine Development Group, Baylor College of Medicine, Houston, Texas, USA
| | - Jacob J Zulk
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- TAILOR Labs, Vaccine Development Group, Baylor College of Medicine, Houston, Texas, USA
| | - Dylan M Chirman
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- TAILOR Labs, Vaccine Development Group, Baylor College of Medicine, Houston, Texas, USA
| | - Felipe-Andres Piedra
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Ellen E Vaughan
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Haroldo J Hernandez Santos
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- TAILOR Labs, Vaccine Development Group, Baylor College of Medicine, Houston, Texas, USA
| | - Kathryn A Patras
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, Texas, USA
| | - Anthony W Maresso
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- TAILOR Labs, Vaccine Development Group, Baylor College of Medicine, Houston, Texas, USA
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Ulhuq FR, Mariano G. Bacterial pore-forming toxins. MICROBIOLOGY (READING, ENGLAND) 2022; 168:001154. [PMID: 35333704 PMCID: PMC9558359 DOI: 10.1099/mic.0.001154] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/03/2022] [Indexed: 12/11/2022]
Abstract
Pore-forming toxins (PFTs) are widely distributed in both Gram-negative and Gram-positive bacteria. PFTs can act as virulence factors that bacteria utilise in dissemination and host colonisation or, alternatively, they can be employed to compete with rival microbes in polymicrobial niches. PFTs transition from a soluble form to become membrane-embedded by undergoing large conformational changes. Once inserted, they perforate the membrane, causing uncontrolled efflux of ions and/or nutrients and dissipating the protonmotive force (PMF). In some instances, target cells intoxicated by PFTs display additional effects as part of the cellular response to pore formation. Significant progress has been made in the mechanistic description of pore formation for the different PFTs families, but in several cases a complete understanding of pore structure remains lacking. PFTs have evolved recognition mechanisms to bind specific receptors that define their host tropism, although this can be remarkably diverse even within the same family. Here we summarise the salient features of PFTs and highlight where additional research is necessary to fully understand the mechanism of pore formation by members of this diverse group of protein toxins.
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Affiliation(s)
- Fatima R. Ulhuq
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Giuseppina Mariano
- Microbes in Health and Disease Theme, Newcastle University Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
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