1
|
Gao P, Wei Y, Hou S, Lai PM, Liu H, Tai SSC, Tang VYM, Prakash PH, Sze KH, Chen JHK, Sun H, Li X, Kao RYT. SaeR as a novel target for antivirulence therapy against Staphylococcus aureus. Emerg Microbes Infect 2023; 12:2254415. [PMID: 37671453 PMCID: PMC10494732 DOI: 10.1080/22221751.2023.2254415] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 09/07/2023]
Abstract
Staphylococcus aureus is a major human pathogen responsible for a wide range of clinical infections. SaeRS is one of the two-component systems in S. aureus that modulate multiple virulence factors. Although SaeR is required for S. aureus to develop an infection, inhibitors have not been reported. Using an in vivo knockdown method, we demonstrated that SaeR is targetable for the discovery of antivirulence agent. HR3744 was discovered through a high-throughput screening utilizing a GFP-Lux dual reporter system driven by saeP1 promoter. The antivirulence efficacy of HR3744 was tested using Western blot, Quantitative Polymerase Chain Reaction, leucotoxicity, and haemolysis tests. In electrophoresis mobility shift assay, HR3744 inhibited SaeR-DNA probe binding. WaterLOGSY-NMR test showed HR3744 directly interacted with SaeR's DNA-binding domain. When SaeR was deleted, HR3744 lost its antivirulence property, validating the target specificity. Virtual docking and mutagenesis were used to confirm the target's specificity. When Glu159 was changed to Asn, the bacteria developed resistance to HR3744. A structure-activity relationship study revealed that a molecule with a slight modification did not inhibit SaeR, indicating the selectivity of HR3744. Interestingly, we found that SAV13, an analogue of HR3744, was four times more potent than HR3744 and demonstrated identical antivirulence properties and target specificity. In a mouse bacteraemia model, both HR3744 and SAV13 exhibited in vivo effectiveness. Collectively, we identified the first SaeR inhibitor, which exhibited in vitro and in vivo antivirulence properties, and proved that SaeR could be a novel target for developing antivirulence drugs against S. aureus infections.
Collapse
Affiliation(s)
- Peng Gao
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Yuanxin Wei
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Suying Hou
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Pok-Man Lai
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Han Liu
- Morningside Laboratory for Chemical Biology and Department of Chemistry, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Sherlock Shing Chiu Tai
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Victor Yat Man Tang
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Pradeep Halebeedu Prakash
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Kong-Hung Sze
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Jonathan Hon Kwan Chen
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| | - Hongzhe Sun
- Morningside Laboratory for Chemical Biology and Department of Chemistry, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Xuechen Li
- Morningside Laboratory for Chemical Biology and Department of Chemistry, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Richard Yi-Tsun Kao
- Department of Microbiology, School of Clinical Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region, China
| |
Collapse
|
2
|
Haag AF, Liljeroos L, Donato P, Pozzi C, Brignoli T, Bottomley MJ, Bagnoli F, Delany I. In Vivo Gene Expression Profiling of Staphylococcus aureus during Infection Informs Design of Stemless Leukocidins LukE and -D as Detoxified Vaccine Candidates. Microbiol Spectr 2023; 11:e0257422. [PMID: 36688711 PMCID: PMC9927290 DOI: 10.1128/spectrum.02574-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 01/02/2023] [Indexed: 01/24/2023] Open
Abstract
Staphylococcus aureus is a clinically important bacterial pathogen that has become resistant to treatment with most routinely used antibiotics. Alternative strategies, such as vaccination and phage therapy, are therefore actively being investigated to prevent or combat staphylococcal infections. Vaccination requires that vaccine targets are expressed at sufficient quantities during infection so that they can be targeted by the host's immune system. While our knowledge of in vitro expression levels of putative vaccine candidates is comprehensive, crucial in vivo expression data are scarce and promising vaccine candidates during in vitro assessment often prove ineffective in preventing S. aureus infection. Here, we show how a newly developed high-throughput quantitative reverse transcription-PCR (qRT-PCR) assay monitoring the expression of 84 staphylococcal genes encoding mostly virulence factors can inform the selection and design of effective vaccine candidates against staphylococcal infections. We show that this assay can accurately quantify mRNA expression levels of these genes in several host organs relying only on very limited amounts of bacterial mRNA in each sample. We selected two highly expressed genes, lukE and lukD, encoding pore-forming leukotoxins, to inform the design of detoxified recombinant proteins and showed that immunization with recombinant genetically detoxified LukED antigens conferred protection against staphylococcal skin infection in mice. Consequently, knowledge of in vivo-expressed virulence determinants can be successfully deployed to identify and select promising candidates for optimized design of effective vaccine antigens against S. aureus. Notably, this approach should be broadly applicable to numerous other pathogens. IMPORTANCE Vaccination is an attractive strategy for preventing bacterial infections in an age of increased antimicrobial resistance. However, vaccine development frequently suffers significant setbacks when candidate antigens that show promising results in in vitro experimentation fail to protect from disease. An alluring strategy is to focus resources on developing bacterial virulence factors that are expressed during disease establishment or maintenance and are critical for bacterial in-host survival as vaccine targets. While expression profiles of many virulence factors have been characterized in detail in vitro, our knowledge of their in vivo expression profiles is still scarce. Here, using a high-throughput qRT-PCR approach, we identified two highly expressed leukotoxins in a murine infection model and showed that genetically detoxified derivatives of these elicited a protective immune response in a murine skin infection model. Therefore, in vivo gene expression can inform the selection of promising candidates for the design of effective vaccine antigens.
Collapse
Affiliation(s)
- Andreas F. Haag
- GSK, Siena, Italy
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom
| | | | | | | | - Tarcisio Brignoli
- GSK, Siena, Italy
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | | | | | | |
Collapse
|
3
|
Gao Y, Chen H, Li W, Zhang Y, Luo J, Zhao L, Shi F, Ye G, He X, Xu Z, Zhu L, Tang H, Li Y. Chloroform extracts of Atractylodes chinensis inhibit the adhesion and invasion of Salmonella typhimurium. Biomed Pharmacother 2022; 154:113633. [PMID: 36063647 DOI: 10.1016/j.biopha.2022.113633] [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: 07/25/2022] [Revised: 08/28/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
There are 27 million cases of Salmonella Typhimurium (STM) reported worldwide annually, which have resulted in 217,000 deaths to date. Thus, there is an urgent requirement to develop novel antibacterial agents to target the multidrug-resistant strains of STM. We evaluated the inhibitory effect of the chloroform extracts of Atractylodes chinensis (Ac-CE) on the virulence of STM in vitro and develop it as a potential antibacterial agent. First, we determined the in vitro effects of Ac-CE on STM biofilm formation, and swimming, swarming, and adhesion to mucin. Further, we evaluated the effect of Ac-CE on the adhesion and invasion of STM at the gene level. Lastly, we evaluated the inhibitory effect of Ac-CE on STM infectivity at the cellular level. Ac-CE could attenuate both the adhesion and invasion abilities of STM in vitro. At the gene level, it could inhibit the expression of flagella, pilus, biofilm, SPI-1, and SPI-2 genes, which are related to the adhesion and invasion ability of STM in cells. Ac-CE significantly downregulated the expression of inflammatory cytokines and the TLR4/MyD88/NF-κB pathway in an STM infection cell model. It also significantly recovered the expression of intestinal barrier-related genes and proteins in intestinal cells that are damaged during STM infection. Ac-CE is effective as an antivirulence agent in alleviating STM infection. Although the main components of Ac-CE were analyzed.We have not demonstrated the antivirulence effect of the active ingredients in Ac-CE. And the antivirulence effect of Ac-CE and its active ingredients warrant further in vivo studies.
Collapse
Affiliation(s)
- Yuanze Gao
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Helin Chen
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Wen Li
- Animal Breeding and Genetics Key Laboratory of Sichuan Province, Sichuan Animal Science Academy, Chengdu 610066, China
| | - Yu Zhang
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Jie Luo
- National Ethnic Affairs Commission Key Open Laboratory of Traditional Chinese Veterinary Medicine, Tongren Polytechnic College, Tongren 554300, Guizhou, China
| | - Ling Zhao
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Fei Shi
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Gang Ye
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Xiaoli He
- College of Science, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Zhiwen Xu
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Ling Zhu
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China
| | - Huaqiao Tang
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China.
| | - Yinglun Li
- College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Chengdu 611130, Sichuan, China.
| |
Collapse
|