Background: C. albicans and C. dubliniensis are closely related but C. albicans is significantly more virulent. The ALS gene family encode proteins that are involved in adhesion in Candida species and are virulence factors. These have been studied in C. albicans, but not in C. dubliniensis.
Methods: ALS gene expression in representative strains of C. dublinicans and C. albicans was investigated under various growth conditions using gene- and species-specific real time PCR primers. Candida adhesion to buccal epithelial cells was investigated by light microscopy.
Results: C. dubliniensis ALS1, ALS3, ALS4, ALS5, ALS6 genes were up-regulated 5, 8, 5, 11 and 9 fold, respectively, following growth at 30°C compared to 37°C. No change in ALSD2 gene expression was detected. C. dubliniensis ALS1, ALS2, ALS3, ALS4, ALS5, ALS6 genes were up-regulated 7, 4, 30, 35, 9 and 6 fold, respectively, when grown in YEPGal compared to YEPD. C. albicans ALS1, ALS6 and ALS7 genes were up-regulated 2.3, 4, 14 fold, respectively, following growth at 30°C compared to 37°C, whereas ALS5 and ALS9 were down regulated 2.3 and 1.6 fold respectively. C. albicans ALS1, ALS6 and ALS7 genes were up-regulated 2.6, 1.1 and 2 fold, respectively, when grown in YEPGal compared to YEPD, whereas ALS5 and ALS9 were down regulated 5.3 and 4 fold, respectively. C. dubliniensis was more adherent when grown at 30°C. Temperature does not appear to affect the adherence of C. albicans to buccal epithelial cells.
Conclusion: Changes in temperature and media affect ALS gene expression in both species. Up-regulation of ALS genes in C. dubliniensis at 30°C coincides with increased adhesion, whereas upregulation of ALS genes in C. dubliniensis grown in YEPGal compared to YEPD does not correlate with increased adhesion.