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Utilization of iron sources and its possible roles in the pathogenesis of Vibrio parahaemolyticus
1Department of Microbiology, Soochow University, Taipei, Taiwan, Republic of China.
Abstract:
Vibrio parahaemolyticus is an important enteropathogen in Japan, Taiwan and other coastal regions. The influence of the regulation of iron on the pathogenesis of this pathogen has not been well characterized. The growth of pathogenic and non-pathogenic strains of V. parahaemolyticus on iron-limited agar plates was stimulated by ferritin, lactoferrin and transferrin at 30 microM, and also by hemin, hemoglobin and ferric ammonium citrate at 100 microM. Spontaneous iron-utilizing mutant strains (mutants) were derived from a clinical strain, ST550. Compared with the parent strain, lowered virulence was demonstrated for these mutants, as assayed by adult mouse and suckling mouse models. The in vivo growth and enterotoxigenicity of these mutants were also lower in the suckling mice. Adherence of the mutants to excised mouse intestine was lower as demonstrated by scanning electron microscopy. The iron-regulated outer membrane protein profile also changed in selected mutants. These results indicate that iron-regulated outer membrane proteins and other unknown factors associated with iron utilization may have profound influences, besides iron acquisition, on the pathogenesis of V. parahaemolyticus.
Insights
Iron utilization influences Vibrio parahaemolyticus pathogenesis. Iron-utilizing mutants showed reduced virulence, in vivo growth, and adherence, indicating iron regulation
Area of Science:
- Microbiology
- Pathogenesis
- Bacterial Physiology
Background:
- Vibrio parahaemolyticus is a significant enteropathogen in coastal regions.
- The role of iron regulation in V. parahaemolyticus pathogenesis is not well understood.
Purpose of the Study:
- To investigate the influence of iron regulation on V. parahaemolyticus pathogenesis.
- To characterize iron-utilizing mutants of V. parahaemolyticus.
Main Methods:
- Assessing growth stimulation by iron sources (ferritin, lactoferrin, transferrin, hemin, hemoglobin, ferric ammonium citrate).
- Deriving and analyzing spontaneous iron-utilizing mutants from a clinical strain (ST550).
- Evaluating mutant virulence using adult and suckling mouse models, in vivo growth, enterotoxigenicity, and intestinal adherence via scanning electron microscopy.
Main Results:
- Growth of V. parahaemolyticus strains was stimulated by various iron compounds.
- Iron-utilizing mutants exhibited significantly reduced virulence, in vivo growth, and enterotoxigenicity compared to the parent strain.
- Mutants showed decreased adherence to mouse intestine, and altered iron-regulated outer membrane protein profiles were observed.
Conclusions:
- Iron utilization is crucial for V. parahaemolyticus pathogenesis.
- Iron-regulated outer membrane proteins and other iron-related factors impact virulence beyond simple iron acquisition.