Comparative proteomic analysis of Cronobacter sakazakii isolates with different virulences.
Cronobacter is a genus of widespread, opportunistic, foodborne pathogens that can result in serious illnesses in at-risk infants because of their immature immunity and high dependence on powdered formula, which is one of the foods most often contaminated by this pathogen. However, limited information is available regarding the pathogenesis and the specific virulence factors of this species. In this study, the virulences of 42 Cronobacter sakazakii isolates were analyzed by infecting neonatal SD rats. A comparison of the typing patterns of the isolates enabled groups with close relationships but that exhibited distinct pathogenesis to be identified. Among these groups, 2 strains belonging to the same group but showing distinct virulences were selected, and 2-DE was applied to identify differentially expressed proteins, focusing on virulence-related proteins. A total of 111 protein spots were identified using matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF/TOF-MS), and 89 were successfully identified. Further analysis suggested that at least 11 of these proteins may be involved in the pathogenesis of this pathogen. Real-time PCR was carried out to further confirm the differential expression pattern of the genes, and the results indicated that the mRNA expression levels were consistent with the protein expression levels.


CONCLUSIONS
The virulence factors and pathogenesis of Cronobacter are largely unknown. In combination with animal toxicological experiments and subtyping results of C. sakazakii, comparative proteomics analysis was performed to comprehensively evaluate the differentially expressed proteins of two isolates that exhibited distinct virulence but were closely related. These procedures made it possible to identify the virulence-related of factors of Cronobacter. Among the 89 total identified proteins, at least 11 show virulence-related potential. This work provides comprehensive candidates for the further investigation of the pathogenesis of Cronobacter.
Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin 300457, China.
Xin-jun
XJ
Du
Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin 300457, China.
Ran
R
Han
Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin 300457, China.
Ping
P
Li
Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin 300457, China. Electronic address: s.wang@tust.edu.cn.
Shuo
S
Wang
D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D044083:Cronobacter sakazakii / Q000145:classification / Q000378:metabolism* / Q000472:pathogenicity*; D006801:Humans; D020543:Proteome / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D014774:Virulence / Q000502:physiology*; D037521:Virulence Factors / Q000378:metabolism*
D001426:Bacterial Proteins; D020543:Proteome; D037521:Virulence Factors
Comparative proteomic analysis; Cronobacter sakazakii; Oral gavage; Real-time PCR; Virulence factors