[Kinetics of Pseudomonas aeruginosa virulence gene expression during chronic lung infection in the murine model].
Pseudomonas aeruginosa is a Gram-negative bacillus frequently encountered in human diseases. P. aeruginosa produces a large number of secreted and cell associated virulence factors. Their production is coordinated by various systems of gene regulation. The correlation and sequential intervention of regulation systems during a pulmonary infection have not been determined yet.


OBJECTIVE
The aim of this study was to analyze the expression of three P. aeruginosa virulence genes (exoS, lasI, and algD) during the first seven days of chronic lung infection. To do so, mice were infected intratracheally with agarose beads containing P. aeruginosa.


RESULTS
The results were a progressive decrease of exoS transcription and an increase of algD, and lasI transcription during infection. This dynamic evolution was consistent with the clinical observation, which demonstrated a progressive loss of type III secretion system function and an increase in the mucoid phenotype development in P. aeruginosa strains from cystic fibrosis patients.


CONCLUSIONS
The development of a P. aeruginosa pulmonary chronic infection associates a decrease of gene expression related to a type III secretion system and an increase of alginate production.
Pierre
M
M
EA 3925, unité de gastroentérologie, hépatologie et nutrition, laboratoire de bactériologie-hygiène, centre de biologie-pathologie, clinique de pédiatrie, hôpital Jeanne-de-Flandre, CHRU de Lille, 59037 Lille, France.
Le Berre
R
R
Tiesset
H
H
Faure
K
K
Guery
B
B
Desseyn
J-L
JL
Galabert
C
C
Béghin
L
L
Beermann
C
C
Gottrand
F
F
Husson
M-O
MO
D000818:Animals; D017931:DNA Primers; D004195:Disease Models, Animal; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D011552:Pseudomonas Infections / Q000503:physiopathology*; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics*
D017931:DNA Primers