The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Huanchun Chen - One of the best experts on this subject based on the ideXlab platform.
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The CpxAR Two-Component System Contributes to Growth, Stress Resistance, and Virulence of Actinobacillus Pleuropneumoniae by Upregulating wecA Transcription.
Frontiers in Microbiology, 2020Co-Authors: Benzhen Duan, Huanchun Chen, Wei Peng, Fangyan YuanAbstract:Actinobacillus Pleuropneumoniae is the pathogen of porcine Contagious Pleuropneumonia. In A. Pleuropneumoniae, the CpxAR two-component system is essential for fitness and growth. The O-antigen protrudes from the outer membrane to the exterior of the cell, and the outer membrane serves as a barrier that helps the bacteria to survive in harsh environments. WecA, a undecaprenyl phosphate GlcNAc-1-phosphate transferase, is involved in O-antigen repeating unit biosynthesis. In this study, we investigated the role of CpxAR in the expression of wecA in A. Pleuropneumoniae. Our results revealed that CpxR positively regulates wecA expression by directly binding to the putative promoter region of wecA. Wild-type, ΔcpxAR, ΔwecA, and complemented strains were investigated under serum, oxidative, and osmotic stresses. The ΔcpxAR and ΔwecA strains were more susceptible to these stresses than the wild-type, but the complemented strains showed phenotypes similar to those of the wild-type. Mice infected with the ΔcpxAR and ΔwecA strains exhibited lower mortality and bacterial loads in the lung than those infected with the wild-type or complemented strains. This study reveals that the CpxAR two-component system contributes to A. Pleuropneumoniae growth, stress resistance, and virulence, by upregulating expression of wecA. Our findings provide new insight into the pathogenesis of A. Pleuropneumoniae.
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The CpxA/CpxR Two-Component System Affects Biofilm Formation and Virulence in Actinobacillus Pleuropneumoniae
Frontiers in Cellular and Infection Microbiology, 2018Co-Authors: Huan Li, Wei Peng, Haixu Zhao, Hui Cheng, Peixi Chang, Fangyan Yuan, Huanchun ChenAbstract:: Gram-negative bacteria have evolved numerous two-component systems (TCSs) to cope with external environmental changes. The CpxA/CpxR TCS consisting of the kinase CpxA and the regulator CpxR, is known to be involved in the biofilm formation and virulence of Escherichia coli. However, the role of CpxA/CpxR remained unclear in Actinobacillus Pleuropneumoniae, a bacterial pathogen that can cause porcine Contagious Pleuropneumonia (PCP). In this report, we show that CpxA/CpxR contributes to the biofilm formation ability of A. Pleuropneumoniae. Furthermore, we demonstrate that CpxA/CpxR plays an important role in the expression of several biofilm-related genes in A. Pleuropneumoniae, such as rpoE and pgaC. Furthermore, The results of electrophoretic mobility shift assays (EMSAs) and DNase I footprinting analysis demonstrate that CpxR-P can regulate the expression of the pgaABCD operon through rpoE. In an experimental infection of mice, the animals infected with a cpxA/cpxR mutant exhibited delayed mortality and lower bacterial loads in the lung than those infected with the wildtype bacteria. In conclusion, these results indicate that the CpxA/CpxR TCS plays a contributing role in the biofilm formation and virulence of A. Pleuropneumoniae.
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Genome-wide evidence for positive selection and recombination in Actinobacillus Pleuropneumoniae.
BMC Evolutionary Biology, 2011Co-Authors: Zhuofei Xu, Huanchun Chen, Rui ZhouAbstract:Background: Actinobacillus Pleuropneumoniae is an economically important animal pathogen that causes Contagious Pleuropneumonia in pigs. Currently, the molecular evolutionary trajectories for this pathogenic bacterium remain to require a better elucidation under the help of comparative genomics data. For this reason, we employed a comparative phylogenomic approach to obtain a comprehensive understanding of roles of natural selective pressure and homologous recombination during adaptation of this pathogen to its swine host. Results: In this study, 12 A. Pleuropneumoniae genomes were used to carry out a phylogenomic analyses. We identified 1,587 orthologous core genes as an initial data set for the estimation of genetic recombination and positive selection. Based on the analyses of four recombination tests, 23% of the core genome of A. Pleuropneumoniae showed strong signals for intragenic homologous recombination. Furthermore, the selection analyses indicated that 57 genes were undergoing significant positive selection. Extensive function properties underlying these positively selected genes demonstrated that genes coding for products relevant to bacterial surface structures and pathogenesis are prone to natural selective pressure, presumably due to their potential roles in the avoidance of the porcine immune system. Conclusions: Overall, substantial genetic evidence was shown to indicate that recombination and positive selection indeed play a crucial role in the adaptive evolution of A. Pleuropneumoniae. The genome-wide profile of positively selected genes and/or amino acid residues will provide valuable targets for further research into the mechanisms of immune evasion and host-pathogen interactions for this serious swine pathogen.
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Construction and characterization of Actinobacillus Pleuropneumoniae serovar 7 live attenuated vaccine strain co-expressing ApxIA
Chinese Journal of Biotechnology, 2010Co-Authors: Yan Chen, Linlin Hu, Huanchun ChenAbstract:: Actinobacillus Pleuropneumoniae (A. Pleuropneumoniae), the causative agent of porcine Contagious Pleuropneumonia (PCP), is a significant pathogen of the world pig industry, vaccination is potentially an effective tool for the prevention of PCP. The purpose of present study was to enhance the immunogenicity of A. Pleuropneumoniae live vaccine strain HB04C- (serovar 7), which was unable to express ApxIA, and to develop effective multivalent vaccines for the respiratory pathogens based on the attenuated A. Pleuropneumoniae. We introduced a shuttle vector containing intact apxIA gene into HB04C-, generating HB04C2, an A. Pleuropneumoniae serovar 7 live attenuated vaccine strain co-expressing ApxIA. Then we investigated the biological characteristics of HB04C2. We found that the shuttle vector expressing ApxIA was stable in HB04C2, and the growth ability of HB04C2 was not affected by the shuttle vector. We observed that HB04C2 elicited detectable antibodies against ApxIA and ApxIIA when it was administrated intratracheally as a live vaccine in pigs, and all immunized pigs were protected from heterologous virulent A. Pleuropneumoniae (serovar 1) challenge. In conclusion, we demonstrated that A. Pleuropneumoniae live vaccine could be used as a vector for expression of heterologous antigens.
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Immunoproteomic analysis of outer membrane proteins and extracellular proteins of Actinobacillus Pleuropneumoniae JL03 serotype 3.
BMC Microbiology, 2009Co-Authors: Yonghong Liao, Junhua Deng, Anding Zhang, Mingguang Zhou, Yong Hu, Huanchun ChenAbstract:Background Actinobacillus Pleuropneumoniae is the causative agent of porcine Contagious Pleuropneumonia, a highly Contagious respiratory infection in pigs, and all the 15 serotypes are able to cause disease. Current vaccines including subunit vaccines could not provide satisfactory protection against A. Pleuropneumoniae. In this study, the immunoproteomic approach was applied to the analysis of extracellular and outer membrane proteins of A. Pleuropneumoniae JL03 serotype 3 for the identification of novel immunogenic proteins for A. Pleuropneumoniae.
Xiaobo Huang - One of the best experts on this subject based on the ideXlab platform.
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Polyamine-binding protein PotD2 is required for stress tolerance and virulence in Actinobacillus Pleuropneumoniae.
Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 2017Co-Authors: Qin Zhao, Yu Zhao, Fei Zhang, Xiaobo Huang, Rui Wu, Yong HuangAbstract:Actinobacillus Pleuropneumoniae is the cause of porcine Contagious Pleuropneumonia, which is one of the most important respiratory diseases in swine and causes huge economic losses in the swine industry. PotD, a polyamine-binding protein, has been well characterised in many pathogens of humans and animals. In this study, a ΔpotD2 mutant of A. Pleuropneumoniae strain MS71 (serovar 1) was constructed successfully by homologous recombination. Growth curves of different strains showed that the growth of the ΔpotD2 mutant was affected greatly in the logarithmic phase compared with that of parental strain. In vitro stress assays revealed that the viability of ΔpotD2 mutant strain was significantly impaired under multiple environmental stresses, including high temperature, oxidation and hyperosmosis. Additionally, the ΔpotD2 mutant caused significantly decreased mortality in a mouse model. Taken together, the findings in this study suggest an important role of PotD2 in the growth, stress tolerance and virulence of A. Pleuropneumoniae.
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A TolC-Like Protein of Actinobacillus Pleuropneumoniae Is Involved in Antibiotic Resistance and Biofilm Formation.
Frontiers in Microbiology, 2016Co-Authors: Ying Li, Qin Zhao, Xiaobo Huang, Rui Wu, Luhua Zhang, Yong HuangAbstract:Actinobacillus Pleuropneumoniae is the etiologic agent of porcine Contagious Pleuropneumonia, a significant disease that causes serious economic losses to the swine industry worldwide. Persistent infections caused by bacterial biofilms are recalcitrant to treat because of the particular drug resistance of biofilm-dwelling cells. TolC, a key component of multidrug efflux pumps, are responsible for multidrug resistance in many Gram-negative bacteria. In this study, we identified two TolC-like proteins, TolC1 and TolC2, in A. Pleuropneumoniae. Deletion of tolC1, but not tolC2, caused a significant reduction in biofilm formation, as well as increased drug sensitivity of both planktonic and biofilm cells. The genetic-complementation of the tolC1 mutation restored the competent biofilm and drug resistance. Besides, biofilm formation was inhibited and drug sensitivity was increased by the addition of phenylalanine-arginine beta-naphthylamide (PAβN), a well-known efflux pump inhibitor (EPI), suggesting a role for EPI in antibacterial strategies towards drug tolerance of A. Pleuropneumoniae. Taken together, TolC1 is required for biofilm formation and is a part of the multidrug resistance machinery of both planktonic and biofilm cells, which could supplement therapeutic strategies for resistant bacteria and biofilm-related infections of A. Pleuropneumoniae clinical isolate SC1516.
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Absence of TolC Impairs Biofilm Formation in Actinobacillus Pleuropneumoniae by Reducing Initial Attachment.
PLOS ONE, 2016Co-Authors: Ying Li, Qin Zhao, Rui Wu, Luhua Zhang, Jianlin Yuan, Xiaobo HuangAbstract:Actinobacillus Pleuropneumoniae is the etiologic agent of porcine Contagious Pleuropneumonia, a major cause of economic loss in swine industry worldwide. TolC, the key component of multidrug efflux pumps and type I secretion systems, has been well-studied as an exit duct for numerous substances in many Gram-negative bacteria. By contrast, little is known on the role of TolC in biofilm formation. In this study, a ΔtolC mutant was used to examine the importance of TolC in biofilm formation of A. Pleuropneumoniae. Surface attachment assays demonstrated the essential role of TolC in initial attachment of biofilm cells. The loss of TolC function altered surface hydrophobicity, and resulted in greatly reduced autoaggregation in ΔtolC. Using both enzymatic treatments and confocal microscopy, biofilm composition and architecture were characterized. When compared against the wild-type strain, the poly-β-1, 6-N-acetyl-D-glucosamine (PGA), an important biofilm matrix component of A. Pleuropneumoniae, was significantly reduced at the initial attachment stage in ΔtolC. These results were confirmed by mRNA level using quantitative RT-PCR. Additionally, defective secretion systems in ΔtolC may also contribute to the deficiency in biofilm formation. Taken together, the current study demonstrated the importance of TolC in the initial biofilm formation stage in A. Pleuropneumoniae. These findings could have important clinical implications in developing new treatments against biofilm-related infections by A. Pleuropneumoniae.
Lu Li - One of the best experts on this subject based on the ideXlab platform.
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Histone-like protein H-NS regulates biofilm formation and virulence of Actinobacillus Pleuropneumoniae
Microbial Pathogenesis, 2008Co-Authors: Baolige Dalai, Rui Zhou, Mingsong Kang, Lu Li, Tingting Li, Sihua Zhang, Huanchun ChenAbstract:Actinobacillus Pleuropneumoniae is the causative agent of porcine Contagious Pleuropneumonia, a very important swine respiratory infectious disease causing great economic losses worldwide. The pathogenesis of this disease is still not completely understood. Biofilm formation contributes to full virulence in many Gram-negative bacterial pathogens. In the present study, two biofilm-producing mutants were identified from the transposon mutagenesis mutant pools of A. Pleuropneumoniae strain 4074 of serovar 1 (a non-biofilm forming strain). Inverse PCR and sequencing analysis revealed that the hns gene encoding the histone-like nucleoid structuring protein (H-NS) was inactivated by the mini-Tn10 transposon in both mutant strains. Further analysis revealed that the virulence was attenuated in the mutant strains when their haemolytic activity and 50% lethal doses in mice were compared with the parental strain. Real-time RT-PCR analysis suggested that the down-regulation of the exotoxin genes in the hns mutants may partly contribute to the virulence attenuation. Our data indicate that H-NS plays important roles in regulating biofilm formation and virulence in A. Pleuropneumoniae.
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Enhanced biofilm formation and reduced virulence of Actinobacillus Pleuropneumoniae luxS mutant
Microbial Pathogenesis, 2008Co-Authors: Lu Li, Rui Zhou, Mingsong Kang, Tingting Li, Zhuofei Xu, Huanchun ChenAbstract:Abstract Actinobacillus Pleuropneumoniae is the pathogen of porcine Contagious Pleuropneumonia causing great economic losses globally. LuxS is known to be involved in the interspecies quorum sensing by mediating the production of AI-2 signal molecule and play important roles in regulating various behaviors of bacteria. In this study, A. Pleuropneumoniae was tested to be able to produce AI-2 like molecule. A luxS deletion mutant strain was constructed by homologous replacement, and its growth features, biofilm formation and virulence were characterized. The luxS mutant showed obvious growth deficiency when cultured in the serum-free medium. Biofilm formation of the mutant strain was significantly enhanced. In a mouse infection model, the 50% lethal dose of the mutant strain was increased up to 96-folds, and the ability to colonize in different mouse tissues was significantly decreased. Down-regulation of apxIIA, a major virulence factor of A. Pleuropneumoniae, may contribute to the virulence attenuation of the mutant strain. Our data demonstrated that LuxS is functional in the AI-2-mediated quorum sensing in A. Pleuropneumoniae and LuxS may regulate different behaviors including biofilm formation and virulence of this important pathogen.
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Genome Biology of Actinobacillus Pleuropneumoniae JL03, an Isolate of Serotype 3 Prevalent in China
PLOS ONE, 2008Co-Authors: Zhuofei Xu, Rui Zhou, Sihua Zhang, Yan Zhou, Liangjun Li, Shaobo Xiao, Kai Wang, Wei Li, Lu LiAbstract:Actinobacillus Pleuropneumoniae is the etiologic agent of porcine Contagious Pleuropneumonia, a cause of considerable world wide economic losses in the swine industry. We sequenced the complete genome of A. Pleuropneumoniae, JL03, an isolate of serotype 3 prevalent in China. Its genome is a single chromosome of 2,242,062 base pairs containing 2,097 predicted protein-coding sequences, six ribosomal rRNA operons, and 63 tRNA genes. Preliminary analysis of the genomic sequence and the functions of the encoded proteins not only confirmed the present physiological and pathological knowledge but also offered new insights into the metabolic and virulence characteristics of this important pathogen. We identified a full spectrum of genes related to its characteristic chemoheterotrophic catabolism of fermentation and respiration with an incomplete TCA system for anabolism. In addition to confirming the lack of ApxI toxin, identification of a nonsense mutation in apxIVA and a 5′-proximal truncation of the flp operon deleting both its promoter and the flp1flp2tadV genes have provided convincing scenarios for the low virulence property of JL03. Comparative genomic analysis using the available sequences of other serotypes, probable strain (serotype)-specific genomic islands related to capsular polysaccharides and lipopolysaccharide O-antigen biosyntheses were identified in JL03, which provides a foundation for future research into the mechanisms of serotypic diversity of A. Pleuropneumoniae.
Rui Zhou - One of the best experts on this subject based on the ideXlab platform.
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Genome-wide evidence for positive selection and recombination in Actinobacillus Pleuropneumoniae.
BMC Evolutionary Biology, 2011Co-Authors: Zhuofei Xu, Huanchun Chen, Rui ZhouAbstract:Background: Actinobacillus Pleuropneumoniae is an economically important animal pathogen that causes Contagious Pleuropneumonia in pigs. Currently, the molecular evolutionary trajectories for this pathogenic bacterium remain to require a better elucidation under the help of comparative genomics data. For this reason, we employed a comparative phylogenomic approach to obtain a comprehensive understanding of roles of natural selective pressure and homologous recombination during adaptation of this pathogen to its swine host. Results: In this study, 12 A. Pleuropneumoniae genomes were used to carry out a phylogenomic analyses. We identified 1,587 orthologous core genes as an initial data set for the estimation of genetic recombination and positive selection. Based on the analyses of four recombination tests, 23% of the core genome of A. Pleuropneumoniae showed strong signals for intragenic homologous recombination. Furthermore, the selection analyses indicated that 57 genes were undergoing significant positive selection. Extensive function properties underlying these positively selected genes demonstrated that genes coding for products relevant to bacterial surface structures and pathogenesis are prone to natural selective pressure, presumably due to their potential roles in the avoidance of the porcine immune system. Conclusions: Overall, substantial genetic evidence was shown to indicate that recombination and positive selection indeed play a crucial role in the adaptive evolution of A. Pleuropneumoniae. The genome-wide profile of positively selected genes and/or amino acid residues will provide valuable targets for further research into the mechanisms of immune evasion and host-pathogen interactions for this serious swine pathogen.
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Histone-like protein H-NS regulates biofilm formation and virulence of Actinobacillus Pleuropneumoniae
Microbial Pathogenesis, 2008Co-Authors: Baolige Dalai, Rui Zhou, Mingsong Kang, Lu Li, Tingting Li, Sihua Zhang, Huanchun ChenAbstract:Actinobacillus Pleuropneumoniae is the causative agent of porcine Contagious Pleuropneumonia, a very important swine respiratory infectious disease causing great economic losses worldwide. The pathogenesis of this disease is still not completely understood. Biofilm formation contributes to full virulence in many Gram-negative bacterial pathogens. In the present study, two biofilm-producing mutants were identified from the transposon mutagenesis mutant pools of A. Pleuropneumoniae strain 4074 of serovar 1 (a non-biofilm forming strain). Inverse PCR and sequencing analysis revealed that the hns gene encoding the histone-like nucleoid structuring protein (H-NS) was inactivated by the mini-Tn10 transposon in both mutant strains. Further analysis revealed that the virulence was attenuated in the mutant strains when their haemolytic activity and 50% lethal doses in mice were compared with the parental strain. Real-time RT-PCR analysis suggested that the down-regulation of the exotoxin genes in the hns mutants may partly contribute to the virulence attenuation. Our data indicate that H-NS plays important roles in regulating biofilm formation and virulence in A. Pleuropneumoniae.
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Enhanced biofilm formation and reduced virulence of Actinobacillus Pleuropneumoniae luxS mutant
Microbial Pathogenesis, 2008Co-Authors: Lu Li, Rui Zhou, Mingsong Kang, Tingting Li, Zhuofei Xu, Huanchun ChenAbstract:Abstract Actinobacillus Pleuropneumoniae is the pathogen of porcine Contagious Pleuropneumonia causing great economic losses globally. LuxS is known to be involved in the interspecies quorum sensing by mediating the production of AI-2 signal molecule and play important roles in regulating various behaviors of bacteria. In this study, A. Pleuropneumoniae was tested to be able to produce AI-2 like molecule. A luxS deletion mutant strain was constructed by homologous replacement, and its growth features, biofilm formation and virulence were characterized. The luxS mutant showed obvious growth deficiency when cultured in the serum-free medium. Biofilm formation of the mutant strain was significantly enhanced. In a mouse infection model, the 50% lethal dose of the mutant strain was increased up to 96-folds, and the ability to colonize in different mouse tissues was significantly decreased. Down-regulation of apxIIA, a major virulence factor of A. Pleuropneumoniae, may contribute to the virulence attenuation of the mutant strain. Our data demonstrated that LuxS is functional in the AI-2-mediated quorum sensing in A. Pleuropneumoniae and LuxS may regulate different behaviors including biofilm formation and virulence of this important pathogen.
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Genome Biology of Actinobacillus Pleuropneumoniae JL03, an Isolate of Serotype 3 Prevalent in China
PLOS ONE, 2008Co-Authors: Zhuofei Xu, Rui Zhou, Sihua Zhang, Yan Zhou, Liangjun Li, Shaobo Xiao, Kai Wang, Wei Li, Lu LiAbstract:Actinobacillus Pleuropneumoniae is the etiologic agent of porcine Contagious Pleuropneumonia, a cause of considerable world wide economic losses in the swine industry. We sequenced the complete genome of A. Pleuropneumoniae, JL03, an isolate of serotype 3 prevalent in China. Its genome is a single chromosome of 2,242,062 base pairs containing 2,097 predicted protein-coding sequences, six ribosomal rRNA operons, and 63 tRNA genes. Preliminary analysis of the genomic sequence and the functions of the encoded proteins not only confirmed the present physiological and pathological knowledge but also offered new insights into the metabolic and virulence characteristics of this important pathogen. We identified a full spectrum of genes related to its characteristic chemoheterotrophic catabolism of fermentation and respiration with an incomplete TCA system for anabolism. In addition to confirming the lack of ApxI toxin, identification of a nonsense mutation in apxIVA and a 5′-proximal truncation of the flp operon deleting both its promoter and the flp1flp2tadV genes have provided convincing scenarios for the low virulence property of JL03. Comparative genomic analysis using the available sequences of other serotypes, probable strain (serotype)-specific genomic islands related to capsular polysaccharides and lipopolysaccharide O-antigen biosyntheses were identified in JL03, which provides a foundation for future research into the mechanisms of serotypic diversity of A. Pleuropneumoniae.
Qin Zhao - One of the best experts on this subject based on the ideXlab platform.
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Polyamine-binding protein PotD2 is required for stress tolerance and virulence in Actinobacillus Pleuropneumoniae.
Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology, 2017Co-Authors: Qin Zhao, Yu Zhao, Fei Zhang, Xiaobo Huang, Rui Wu, Yong HuangAbstract:Actinobacillus Pleuropneumoniae is the cause of porcine Contagious Pleuropneumonia, which is one of the most important respiratory diseases in swine and causes huge economic losses in the swine industry. PotD, a polyamine-binding protein, has been well characterised in many pathogens of humans and animals. In this study, a ΔpotD2 mutant of A. Pleuropneumoniae strain MS71 (serovar 1) was constructed successfully by homologous recombination. Growth curves of different strains showed that the growth of the ΔpotD2 mutant was affected greatly in the logarithmic phase compared with that of parental strain. In vitro stress assays revealed that the viability of ΔpotD2 mutant strain was significantly impaired under multiple environmental stresses, including high temperature, oxidation and hyperosmosis. Additionally, the ΔpotD2 mutant caused significantly decreased mortality in a mouse model. Taken together, the findings in this study suggest an important role of PotD2 in the growth, stress tolerance and virulence of A. Pleuropneumoniae.
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A TolC-Like Protein of Actinobacillus Pleuropneumoniae Is Involved in Antibiotic Resistance and Biofilm Formation.
Frontiers in Microbiology, 2016Co-Authors: Ying Li, Qin Zhao, Xiaobo Huang, Rui Wu, Luhua Zhang, Yong HuangAbstract:Actinobacillus Pleuropneumoniae is the etiologic agent of porcine Contagious Pleuropneumonia, a significant disease that causes serious economic losses to the swine industry worldwide. Persistent infections caused by bacterial biofilms are recalcitrant to treat because of the particular drug resistance of biofilm-dwelling cells. TolC, a key component of multidrug efflux pumps, are responsible for multidrug resistance in many Gram-negative bacteria. In this study, we identified two TolC-like proteins, TolC1 and TolC2, in A. Pleuropneumoniae. Deletion of tolC1, but not tolC2, caused a significant reduction in biofilm formation, as well as increased drug sensitivity of both planktonic and biofilm cells. The genetic-complementation of the tolC1 mutation restored the competent biofilm and drug resistance. Besides, biofilm formation was inhibited and drug sensitivity was increased by the addition of phenylalanine-arginine beta-naphthylamide (PAβN), a well-known efflux pump inhibitor (EPI), suggesting a role for EPI in antibacterial strategies towards drug tolerance of A. Pleuropneumoniae. Taken together, TolC1 is required for biofilm formation and is a part of the multidrug resistance machinery of both planktonic and biofilm cells, which could supplement therapeutic strategies for resistant bacteria and biofilm-related infections of A. Pleuropneumoniae clinical isolate SC1516.
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Absence of TolC Impairs Biofilm Formation in Actinobacillus Pleuropneumoniae by Reducing Initial Attachment.
PLOS ONE, 2016Co-Authors: Ying Li, Qin Zhao, Rui Wu, Luhua Zhang, Jianlin Yuan, Xiaobo HuangAbstract:Actinobacillus Pleuropneumoniae is the etiologic agent of porcine Contagious Pleuropneumonia, a major cause of economic loss in swine industry worldwide. TolC, the key component of multidrug efflux pumps and type I secretion systems, has been well-studied as an exit duct for numerous substances in many Gram-negative bacteria. By contrast, little is known on the role of TolC in biofilm formation. In this study, a ΔtolC mutant was used to examine the importance of TolC in biofilm formation of A. Pleuropneumoniae. Surface attachment assays demonstrated the essential role of TolC in initial attachment of biofilm cells. The loss of TolC function altered surface hydrophobicity, and resulted in greatly reduced autoaggregation in ΔtolC. Using both enzymatic treatments and confocal microscopy, biofilm composition and architecture were characterized. When compared against the wild-type strain, the poly-β-1, 6-N-acetyl-D-glucosamine (PGA), an important biofilm matrix component of A. Pleuropneumoniae, was significantly reduced at the initial attachment stage in ΔtolC. These results were confirmed by mRNA level using quantitative RT-PCR. Additionally, defective secretion systems in ΔtolC may also contribute to the deficiency in biofilm formation. Taken together, the current study demonstrated the importance of TolC in the initial biofilm formation stage in A. Pleuropneumoniae. These findings could have important clinical implications in developing new treatments against biofilm-related infections by A. Pleuropneumoniae.