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[Virulence of Candida dubliniensis in comparison with Candida albicans using an experimental model of mouse oral
Hiroo Yoshioka1, Shoko Ito-Kuwa, Kenjirou Nakamura
1Oral and Maxillofacial Surgery and Systemic Medicine, Graduate School of Life Dentistry, Nippon Dental University at Niigata.
Abstract:
Certain species of Candida are known as opportunistic fungal pathogens and Candida albicans has especially been isolated oral candidiasis patients at high frequency as a result of its strong pathogenicity. Recently C. dubliniensis is isolated mainly from immunocompromised patients, but is also detected from healthy persons. C. dubliniensis has similar cell morphology and molecular biological properties to C. albicans. Thus, in order to clarify the pathogenicity of C. dubliniensis, the activities of two extracellular enzymes, phospholipase (PL) and proteinase (PT), were measured, and pathological features were compared using mice. PL activity was examined in the improved Price's PL activity assay. In brief, the white precipitation zone was detected by spraying NaCl on egg yold plates without NaCl after colonies had grown. PL activity was no detected in any of the 31 C. dubliniensis strains tested. On the other hand, PT acitivty of C. dubliniensis was almost equivalent to that of C. albicans. Although we attempted to make an experimental model of mouse oral candidiasis using C. dubliniensis in yeast form as an inoculum following the conventional method, oral candidiasis did not develop in any mice. Thrush was successfully developed after inoculation with mycelial form cells, and there was no significant difference in histopathological findings of the thrush in comparison with C. albicans. These results strongly suggest that the two enzymes, PT and PL, do not play a crusial role in the establishment of mouse oral experimental candidiasis by C. dubliniensis.
Insights
Candida dubliniensis causes oral candidiasis in mice, similar to Candida albicans, but its phospholipase activity is undetectable. Proteinase activity is similar between the two species, suggesting these enzymes are not crucial for oral candidiasis establishment.
Area of Science:
- Mycology
- Pathogen Biology
- Immunocompromised Host Research
Background:
- Opportunistic fungal pathogens, like Candida species, cause infections, particularly oral candidiasis.
- Candida albicans is frequently isolated from oral candidiasis patients due to its pathogenicity.
- Candida dubliniensis, found in immunocompromised and healthy individuals, shares traits with C. albicans.
Purpose of the Study:
- To investigate the pathogenicity of Candida dubliniensis by comparing it with Candida albicans.
- To assess the roles of extracellular enzymes phospholipase (PL) and proteinase (PT) in C. dubliniensis pathogenicity.
- To establish and compare experimental models of oral candidiasis in mice using C. dubliniensis and C. albicans.
Main Methods:
- Phospholipase (PL) activity was measured using an improved Price's assay on egg yolk plates.
- Proteinase (PT) activity was assessed and compared between C. dubliniensis and C. albicans strains.
- Experimental mouse models of oral candidiasis were developed using both yeast and mycelial forms of C. dubliniensis.
Main Results:
- No detectable PL activity was observed in any of the 31 C. dubliniensis strains tested.
- PT activity in C. dubliniensis was comparable to that of C. albicans.
- Oral candidiasis developed in mice inoculated with the mycelial form of C. dubliniensis, with histopathological findings similar to those caused by C. albicans.
Conclusions:
- Phospholipase (PL) activity does not appear to be a critical factor in the establishment of oral candidiasis by C. dubliniensis.
- Proteinase (PT) activity, while present and similar to C. albicans, may not be the sole determinant of pathogenicity in this experimental model.
- The ability of C. dubliniensis to cause oral candidiasis in mice, particularly in its mycelial form, highlights its pathogenic potential, irrespective of detectable PL activity.
