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Kumar A, Drozd M, Pina-Mimbela R, Xu X, Helmy YA, Antwi J, Fuchs JR, Nislow C, Templeton J, Blackall PJ, Rajashekara G. Novel Anti-Campylobacter Compounds Identified Using High Throughput Screening of a Pre-selected Enriched Small Molecules Library. Front Microbiol 2016; 7:405. [PMID: 27092106 PMCID: PMC4821856 DOI: 10.3389/fmicb.2016.00405] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 03/14/2016] [Indexed: 12/12/2022] Open
Abstract
Campylobacter is a leading cause of foodborne bacterial gastroenteritis worldwide and infections can be fatal. The emergence of antibiotic-resistant Campylobacter spp. necessitates the development of new antimicrobials. We identified novel anti-Campylobacter small molecule inhibitors using a high throughput growth inhibition assay. To expedite screening, we made use of a "bioactive" library of 4182 compounds that we have previously shown to be active against diverse microbes. Screening for growth inhibition of Campylobacter jejuni, identified 781 compounds that were either bactericidal or bacteriostatic at a concentration of 200 μM. Seventy nine of the bactericidal compounds were prioritized for secondary screening based on their physico-chemical properties. Based on the minimum inhibitory concentration against a diverse range of C. jejuni and a lack of effect on gut microbes, we selected 12 compounds. No resistance was observed to any of these 12 lead compounds when C. jejuni was cultured with lethal or sub-lethal concentrations suggesting that C. jejuni is less likely to develop resistance to these compounds. Top 12 compounds also possessed low cytotoxicity to human intestinal epithelial cells (Caco-2 cells) and no hemolytic activity against sheep red blood cells. Next, these 12 compounds were evaluated for ability to clear C. jejuni in vitro. A total of 10 compounds had an anti-C. jejuni effect in Caco-2 cells with some effective even at 25 μM concentrations. These novel 12 compounds belong to five established antimicrobial chemical classes; piperazines, aryl amines, piperidines, sulfonamide, and pyridazinone. Exploitation of analogs of these chemical classes may provide Campylobacter specific drugs that can be applied in both human and animal medicine.
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Affiliation(s)
- Anand Kumar
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State UniversityWooster, OH, USA; Poultry CRC, University of New EnglandArmidale, NSW, Australia
| | - Mary Drozd
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State UniversityWooster, OH, USA; Poultry CRC, University of New EnglandArmidale, NSW, Australia
| | - Ruby Pina-Mimbela
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University Wooster, OH, USA
| | - Xiulan Xu
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University Wooster, OH, USA
| | - Yosra A Helmy
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University Wooster, OH, USA
| | - Janet Antwi
- College of Pharmacy, The Ohio State University Columbus, OH, USA
| | - James R Fuchs
- College of Pharmacy, The Ohio State University Columbus, OH, USA
| | - Corey Nislow
- Pharmaceutical Sciences, The University of British Columbia Vancouver, BC, Canada
| | - Jillian Templeton
- Department of Agriculture and Fisheries, EcoSciences Precinct Dutton Park, QLD, Australia
| | - Patrick J Blackall
- Poultry CRC, University of New EnglandArmidale, NSW, Australia; Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, EcoSciences PrecinctDutton Park, QLD, Australia
| | - Gireesh Rajashekara
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University Wooster, OH, USA
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Xu X, Kumar A, Deblais L, Pina-Mimbela R, Nislow C, Fuchs JR, Miller SA, Rajashekara G. Discovery of novel small molecule modulators of Clavibacter michiganensis subsp. michiganensis. Front Microbiol 2015; 6:1127. [PMID: 26539169 PMCID: PMC4609890 DOI: 10.3389/fmicb.2015.01127] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 09/28/2015] [Indexed: 12/05/2022] Open
Abstract
Clavibacter michiganensis subsp. michiganensis (Cmm) is a Gram-positive seed-transmitted bacterial phytopathogen responsible for substantial economic losses by adversely affecting tomato production worldwide. A high-throughput, cell-based screen was adapted to identify novel small molecule growth inhibitors to serve as leads for future bactericide development. A library of 4,182 compounds known to be bioactive against Saccharomyces cerevisiae was selected for primary screening against Cmm wild-type strain C290 for whole-cell growth inhibition. Four hundred sixty-eight molecules (11.2% hit rate) were identified as bacteriocidal or bacteriostatic against Cmm at 200 μM. Seventy-seven candidates were selected based on Golden Triangle analyses for secondary screening. Secondary screens showed that several of these candidates were strain-selective. Several compounds were inhibitory to multiple Cmm strains as well as Bacillus subtilis, but not to Pseudomonas fluorescens, Mitsuaria sp., Lysobacter enzymogenes, Lactobacillus rhamnosus, Bifidobacterium animalis, or Escherichia coli. Most of the compounds were not phytotoxic and did not show overt host toxicity. Using a novel 96-well bioluminescent Cmm seedling infection assay, we assessed effects of selected compounds on pathogen infection. The 12 most potent novel molecules were identified by compiling the scores from all secondary screens combined with the reduction of pathogen infection in planta. When tested for ability to develop resistance to the top-12 compounds, no resistant Cmm were recovered, suggesting that the discovered compounds are unlikely to induce resistance. In conclusion, here we report top-12 compounds that provide chemical scaffolds for future Cmm-specific bactericide development.
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Affiliation(s)
- Xiulan Xu
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University Wooster, OH, USA
| | - Anand Kumar
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University Wooster, OH, USA
| | - Loïc Deblais
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University Wooster, OH, USA
| | - Ruby Pina-Mimbela
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University Wooster, OH, USA
| | - Corey Nislow
- Pharmaceutical Sciences, University of British Columbia Vancouver, BC, Canada
| | - James R Fuchs
- College of Pharmacy, The Ohio State University Columbus, OH, USA
| | - Sally A Miller
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University Wooster, OH, USA
| | - Gireesh Rajashekara
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, The Ohio State University Wooster, OH, USA
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Chandrashekhar K, Gangaiah D, Pina-Mimbela R, Kassem II, Jeon BH, Rajashekara G. Transducer like proteins of Campylobacter jejuni 81-176: role in chemotaxis and colonization of the chicken gastrointestinal tract. Front Cell Infect Microbiol 2015; 5:46. [PMID: 26075188 PMCID: PMC4444964 DOI: 10.3389/fcimb.2015.00046] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 05/11/2015] [Indexed: 01/06/2023] Open
Abstract
Transducer Like Proteins (Tlps), also known as methyl accepting chemotaxis proteins (MCP), enable enteric pathogens to respond to changing nutrient levels in the environment by mediating taxis toward or away from specific chemoeffector molecules. Despite recent advances in the characterization of chemotaxis responses in Campylobacter jejuni, the impact of Tlps on the adaptation of this pathogen to disparate niches and hosts is not fully characterized. The latter is particularly evident in the case of C. jejuni 81-176, a strain that is known to be highly invasive. Furthermore, the cytoplasmic group C Tlps (Tlp5, 6, and 8) were not extensively evaluated. Here, we investigated the role of C. jejuni 81-176 Tlps in chemotaxis toward various substrates, biofilm formation, in vitro interaction with human intestinal cells, and chicken colonization. We found that the Δtlp6 and Δtlp10 mutants exhibited decreased chemotaxis toward aspartate, whereas the Δtlp6 mutant displayed a decreased chemotaxis toward Tri-Carboxylic Acid (TCA) cycle intermediates such as pyruvate, isocitrate, and succinate. Our findings also corroborated that more than one Tlp is involved in mediating chemotaxis toward the same nutrient. The deletion of tlps affected important phenotypes such as motility, biofilm formation, and invasion of human intestinal epithelial cells (INT-407). The Δtlp8 mutant displayed increased motility in soft agar and showed decreased biofilm formation. The Δtlp8 and Δtlp9 mutants were significantly defective in invasion in INT-407 cells. The Δtlp10 mutant was defective in colonization of the chicken proximal and distal gastrointestinal tract, while the Δtlp6 and Δtlp8 mutants showed reduced colonization of the duodenum and jejunum. Our results highlight the importance of Tlps in C. jejuni's adaptation and pathobiology.
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Affiliation(s)
- Kshipra Chandrashekhar
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research Development Center, The Ohio State University Wooster, OH, USA
| | - Dharanesh Gangaiah
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research Development Center, The Ohio State University Wooster, OH, USA
| | - Ruby Pina-Mimbela
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research Development Center, The Ohio State University Wooster, OH, USA
| | - Issmat I Kassem
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research Development Center, The Ohio State University Wooster, OH, USA
| | - Byeong H Jeon
- Department of Environmental Health Sciences, School of Public Health, University of Alberta Edmonton, AB, Canada
| | - Gireesh Rajashekara
- Food Animal Health Research Program, Department of Veterinary Preventive Medicine, Ohio Agricultural Research Development Center, The Ohio State University Wooster, OH, USA
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Malde A, Gangaiah D, Chandrashekhar K, Pina-Mimbela R, Torrelles JB, Rajashekara G. Functional characterization of exopolyphosphatase/guanosine pentaphosphate phosphohydrolase (PPX/GPPA) of Campylobacter jejuni. Virulence 2014; 5:521-33. [PMID: 24569519 DOI: 10.4161/viru.28311] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The inorganic polyphosphate (poly-P) is a key regulator of stress responses and virulence in many bacterial pathogens including Campylobacter jejuni. The role of exopolyphosphatases/guanosine pentaphosphate (pppGpp) phosphohydrolases (PPX/GPPA) in poly-P homeostasis and C. jejuni pathobiology remains unexplored. Here, we analyzed deletion mutants (∆ppx1, ∆ppx2) and the double knockout mutant (dkppx), all ∆ppx mutants exhibited increased capacity to accumulate poly-P; however only ∆ppx1 and dkppx mutants showed decreased accumulation of ppGpp, an alarmone molecule that regulates stringent response in bacteria, suggesting potential dual role for PPX1/GPPA. Nutrient survival defect of ∆ppx mutants was rescued by the supplementation of specific amino acids implying that survival defect may be associated with decreased ppGpp and/ or increased poly-P in ∆ppx mutants. The ppk1 and spoT were upregulated in both ∆ppx1 and ∆ppx2 suggesting a compensatory role for SpoT and Ppk1 in poly-P and ppGpp homeostasis. The lack of ppx genes resulted in defects in motility, biofilm formation, nutrient stress survival, invasion and intracellular survival indicating that maintaining a certain level of poly-P is critical for ppx genes in C. jejuni pathophysiology. Both ppx1 and ppx2 mutants were resistant to human complement-mediated killing; however, the dkppx mutant was sensitive. The serum susceptibility did not occur in the presence of MgCl 2 and EGTA suggesting an involvement of the classical or lectin pathway of complement mediated killing. Interestingly, the chicken serum did not have any effect on the ∆ppx mutants' survival. The observed serum susceptibility was not related to C. jejuni surface capsule and lipooligosaccharide structures. Our study underscores the importance of PPX/GPPA proteins in poly-P and ppGpp homeostasis, two critical molecules that modulate environmental stress responses and virulence in C. jejuni.
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Affiliation(s)
- Anandkumar Malde
- Food Animal Health Research Program; Department of Veterinary Preventive Medicine; College of Veterinary Medicine; The Ohio State University; Wooster, OH USA
| | - Dharanesh Gangaiah
- Food Animal Health Research Program; Department of Veterinary Preventive Medicine; College of Veterinary Medicine; The Ohio State University; Wooster, OH USA
| | - Kshipra Chandrashekhar
- Food Animal Health Research Program; Department of Veterinary Preventive Medicine; College of Veterinary Medicine; The Ohio State University; Wooster, OH USA
| | - Ruby Pina-Mimbela
- Food Animal Health Research Program; Department of Veterinary Preventive Medicine; College of Veterinary Medicine; The Ohio State University; Wooster, OH USA
| | - Jordi B Torrelles
- Department of Microbial Infection and Immunity; Center for Microbial Interface Biology; The Ohio State University; Columbus, OH USA
| | - Gireesh Rajashekara
- Food Animal Health Research Program; Department of Veterinary Preventive Medicine; College of Veterinary Medicine; The Ohio State University; Wooster, OH USA
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Annamalai T, Pina-Mimbela R, Kumar A, Binjawadagi B, Liu Z, Renukaradhya GJ, Rajashekara G. Evaluation of nanoparticle-encapsulated outer membrane proteins for the control of Campylobacter jejuni colonization in chickens. Poult Sci 2013; 92:2201-11. [PMID: 23873570 DOI: 10.3382/ps.2012-03004] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Numerous vaccination strategies have been evaluated to develop effective vaccines against Campylobacter jejuni colonization in poultry but with limited success. The following experiments were conducted to investigate the effect of biodegradable and biocompatible poly (lactide-co-glycolide) nanoparticle (NP) encapsulated outer membrane proteins (OMP) of C. jejuni. Chickens were vaccinated with different routes [subcutaneous (s/c) or oral] and doses (25, 125, or 250 µg) of candidate nanoparticle vaccine with appropriate control groups. Serum and cloacal fecal samples were taken at regular intervals of time, and the birds were euthanized 7 d postchallenge with C. jejuni. The results were interpreted based on anti-OMP immunoglobulin response in chicken and intestinal colonization of C. jejuni. The C. jejuni colonization in cecal and cloacal contents at 7 d postchallenge was below the detection limit in the s/c vaccinated groups, but the other groups demonstrated varying degrees of colonization. The serum IgA was higher in the group vaccinated s/c with OMP only compared with the rest of the groups. The serum- and fecal-IgY titers were consistently higher in the s/c vaccinated groups (with or without NP) than the rest of the groups. Elevated levels of OMP specific serum antibodies correlated with below the limit of detection levels of Campylobacter colonization in broiler chickens receiving 125 μg of OMP alone and the OMP+NP vaccine s/c. In conclusion, the s/c route of vaccination with or without NP encapsulated OMP of C. jejuni may serve as a candidate vaccine for control of C. jejuni colonization in chickens.
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Affiliation(s)
- T Annamalai
- Department of Veterinary Preventive Medicine, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, USA
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