Identification of novel virulence-related genes in Aeromonas hydrophila by screening transposon mutants in a Tetrahymena infection model

Pang, Maoda; Xie, Xiulan; Dong, Yuhao; Du, Hechao; Wang, Nannan; Chen, Lu; Liu, Yongjie

doi:10.1016/j.vetmic.2016.12.021

Cited by 17 publications

(11 citation statements)

References 38 publications

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“…It is known that a single flagellum is sufficient for swimming motility, but most bacteria that swarm require lateral flagella to contact with surfaces (Kearns, 2010 ). However, in our present and previous studies (Pang et al, 2017 ), A. hydrophila NJ-35 was demonstrated to have the swarming ability. Similar phenomenon has been found in Pseudomonas aeruginosa , which could synthesize an alternative motor (Toutain et al, 2005 ) or produce two polar flagella (Köhler et al, 2000 ) during swarming to propel movement on surfaces.…”

Section: Discussioncontrasting

confidence: 69%

Tetrahymena thermophila Predation Enhances Environmental Adaptation of the Carp Pathogenic Strain Aeromonas hydrophila NJ-35

Jin

Dong

Wang

et al. 2018

Front. Cell. Infect. Microbiol.

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Persistence of Aeromonas hydrophila in aquatic environments is the principle cause of fish hemorrhagic septicemia. Protistan predation has been considered to be a strong driving force for the evolution of bacterial defense strategies. In this study, we investigated the adaptive traits of A. hydrophila NJ-35, a carp pathogenic strain, in response to Tetrahymena thermophila predation. After subculturing with Tetrahymena, over 70% of A. hydrophila colonies were small colony variants (SCVs). The SCVs displayed enhanced biofilm formation, adhesion, fitness, and resistance to bacteriophage infection and oxidative stress as compared to the non-Tetrahymena-exposed strains. In contrast, the SCVs exhibited decreased intracellular bacterial number in RAW264.7 macrophages and were highly attenuated for virulence in zebrafish. Considering the outer membrane proteins (OMPs) are directly involved in bacterial interaction with the external surroundings, we investigated the roles of OMPs in the antipredator fitness behaviors of A. hydrophila. A total of 38 differentially expressed proteins were identified in the SCVs by quantitative proteomics. Among them, three lipoproteins including SurA, Slp, and LpoB, and a serine/threonine protein kinase (Stpk) were evidenced to be associated with environmental adaptation of the SCVs. Also, the three lipoproteins were involved in attenuated virulence of SCVs through the proinflammatory immune response mediated by TLR2. This study provides an important contribution to the understanding of the defensive traits of A. hydrophila against protistan predators.

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Section: Discussioncontrasting

confidence: 69%

Tetrahymena thermophila Predation Enhances Environmental Adaptation of the Carp Pathogenic Strain Aeromonas hydrophila NJ-35

Jin

Dong

Wang

et al. 2018

Front. Cell. Infect. Microbiol.

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“…The S. agalactiae strains were cultured on commercial Columbia blood agar plates (KeMaJia) for 24 h to determine their hemolytic phenotype firstly. Then, the hemolytic activity of all strains were measured using culture filtrates of bacteria cultured for 18 h as described previously [ 35 ]. In brief, every 200 μL of culture filtrates, which were adjusted to per mL of cell filtrate per 1 × 10 9 CFU, were added to the well of a 96-well plate.…”

Section: Methodsmentioning

confidence: 99%

Molecular and virulence characterization of highly prevalent Streptococcus agalactiae circulated in bovine dairy herds

Pang

Sun

et al. 2017

Vet Res

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Bovine mastitis caused by Streptococcus agalactiae continues to be one of the major veterinary and economic issues in certain areas of the world. The more prevalent S. agalactiae strains that cause bovine mastitis in China dairy farms belong to a number of bovine-adapted sequence types (STs) ST67, ST103 and ST568. However, it is unknown why these STs can emerge as highly prevalent clones in bovine dairy farms. Here, to determine if a variety of virulence characteristics were associated with these highly prevalent STs, the molecular and virulence characterization of 116 strains isolated from bovine, human, fish and environment were analyzed. Our data showed that all bovine-adapted strains could be assigned to capsular genotype Ia or II, and carried pilus island 2b, and lactose operon. Importantly, we demonstrated that the growth ability in milk, biofilm formation ability and adhesion ability to bovine mammary epithelial cells (BMECs) were significantly higher for all bovine-adapted strains compared to strains from other origins. Additionally, ST103 and ST568 strains exhibited significantly higher hemolytic activity and cytotoxicity than ST67 strains. In conclusion, our study provides substantial evidence for the hypothesis that the virulence characteristics including efficient growth in milk, elevated biofilm formation ability, together with strong adhesion ability might have favored the high prevalence of the STs in the bovine environment, whereas the hemolytic activity and cytotoxicity were not the crucial characteristics.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-017-0461-2) contains supplementary material, which is available to authorized users.

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“…A library containing 947 random EZ-Tn5 transposon mutants based on A. hydrophila NJ-35 was previously constructed in our laboratory [ 21 ]. All the mutants were assayed for hemolytic activity, as described previously [ 44 ], with some minor modifications.…”

Section: Methodsmentioning

confidence: 99%

“…Degenerate primers AD1 to AD6 were paired with SP1 to SP6, respectively, to amplify the flanking sequences of the inserted EZ-Tn5. The detailed operation of the Tail-PCR was performed, as previously described [ 21 ]. After Tail-PCR, the specific products were gel purified and sequenced.…”

Section: Methodsmentioning

confidence: 99%

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Discovery of lahS as a Global Regulator of Environmental Adaptation and Virulence in Aeromonas hydrophila

Dong

Wang

Jin

et al. 2018

IJMS

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Aeromonas hydrophila is an important aquatic microorganism that can cause fish hemorrhagic septicemia. In this study, we identified a novel LysR family transcriptional regulator (LahS) in the A. hydrophila Chinese epidemic strain NJ-35 from a library of 947 mutant strains. The deletion of lahS caused bacteria to exhibit significantly decreased hemolytic activity, motility, biofilm formation, protease production, and anti-bacterial competition ability when compared to the wild-type strain. In addition, the determination of the fifty percent lethal dose (LD50) in zebrafish demonstrated that the lahS deletion mutant (ΔlahS) was highly attenuated in virulence, with an approximately 200-fold increase in LD50 observed as compared with that of the wild-type strain. However, the ΔlahS strain exhibited significantly increased antioxidant activity (six-fold). Label-free quantitative proteome analysis resulted in the identification of 34 differentially expressed proteins in the ΔlahS strain. The differentially expressed proteins were involved in flagellum assembly, metabolism, redox reactions, and cell density induction. The data indicated that LahS might act as a global regulator to directly or indirectly regulate various biological processes in A. hydrophila NJ-35, contributing to a greater understanding the pathogenic mechanisms of A. hydrophila.

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Identification of novel virulence-related genes in Aeromonas hydrophila by screening transposon mutants in a Tetrahymena infection model

Cited by 17 publications

References 38 publications

Tetrahymena thermophila Predation Enhances Environmental Adaptation of the Carp Pathogenic Strain Aeromonas hydrophila NJ-35

Tetrahymena thermophila Predation Enhances Environmental Adaptation of the Carp Pathogenic Strain Aeromonas hydrophila NJ-35

Molecular and virulence characterization of highly prevalent Streptococcus agalactiae circulated in bovine dairy herds

Discovery of lahS as a Global Regulator of Environmental Adaptation and Virulence in Aeromonas hydrophila

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