A secretome-based methodology may provide a better characterization of the virulence of Listeria monocytogenes: preliminary results.
Four strains of Listeria monocytogenes with different levels of virulence were studied. Two strains were consistently evaluated as virulent (strain 3077) and of low virulence (strain 3993), whereas the other two strains (3006 and 3049) originated conflicting results in what the evaluation tests were concerned: both were shown to exhibit low virulence when evaluated by in vitro assays, but virulent when the analyses were performed under in vivo conditions. To clarify the virulence potential of the selected strains, a proteomic approach was used after incubating L. monocytogenes cultures under conditions favoring the expression of virulence factors (minimal medium, at 37 °C). Bacterial proteins present in the liquid culture media were precipitated from late exponential phase cultures, fractionated by SDS-PAGE and identified by MALDI-TOF-MS. Three virulence factors differentially expressed were detected: protein p60, listeriolysin O (LLO) and internalin C (InlC). Clustering analysis of the four L. monocytogenes strains based on their secretome profiles allowed their categorization in two groups: the virulent group, composed by strains 3077 and 3049, and the low virulence group, containing strains 3993 and 3006. The results presented in this work suggest that the virulent potential of a particular L. monocytogenes strain may be predicted from the levels of both listeriolysin O (LLO) and internalin C (InlC) present in its secretome when the bacterium is grown under conditions favoring the expression of virulence factors. Following validation of this proposal through the analysis of a large array of strains, this methodology exhibits a great potential to be developed into an accurate and rapid method to characterize L. monocytogenes strain virulence.
CBAA/Laboratory of Microbiology, Instituto Superior de Agronomia, Technical University of Lisbon, Tapada da Ajuda, 1349-017 Lisbon, Portugal.
Paula
P
Cabrita
Catarina
C
Fonseca
Regina
R
Freitas
Ricardo
R
Carreira
Jose Luis
JL
Capelo
Maria João
MJ
Trigo
Ricardo Boavida
RB
Ferreira
Luisa
L
Brito
D001426:Bacterial Proteins / Q000494:pharmacology; D001427:Bacterial Toxins / Q000494:pharmacology; D002138:Calibration; D016000:Cluster Analysis; D003470:Culture Media / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006360:Heat-Shock Proteins / Q000494:pharmacology; D006460:Hemolysin Proteins / Q000494:pharmacology; D008089:Listeria monocytogenes / Q000378:metabolism*; D008957:Models, Genetic; D040901:Proteomics / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013696:Temperature; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003470:Culture Media; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D037521:Virulence Factors; C103178:inlC protein, Listeria monocytogenes; C038705:hlyA protein, Listeria monocytogenes