Histone-like protein H-NS regulates biofilm formation and virulence of Actinobacillus pleuropneumoniae.
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.
Dalai
Baolige
B
Division of Animal Infectious Diseases, State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Shizishan Street 1, Wuhan 430070, China.
Zhou
Rui
R
Wan
Yun
Y
Kang
Mingsong
M
Li
Lu
L
Li
Tingting
T
Zhang
Sihua
S
Chen
Huanchun
H
D000189:Actinobacillus Infections / Q000382:microbiology; D016977:Actinobacillus pleuropneumoniae / Q000472:pathogenicity* / Q000502:physiology*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D001427:Bacterial Toxins / Q000096:biosynthesis; D018441:Biofilms / Q000254:growth & development*; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005260:Female; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006461:Hemolysis; D007928:Lethal Dose 50; D051379:Mice; D008807:Mice, Inbred BALB C; D016254:Mutagenesis, Insertional; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis*
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; C031908:H-NS protein, bacteria; D037521:Virulence Factors