CANDIDA DUBLINIENSIS - PHYLOGENY AND PUTATIVE VIRULENCE FACTORS

Candida dubliniensis is a recently identified species which is implica ted in oral candidosis in HIV-infected and AIDS patients. The species shares many phenotypic characteristics with, and is phylogenetically c losely related to, Candida albicans, In this study the phylogenetic re lationship between these two species was investigated and a comparison of putative virulence factors was performed. Four isolates of C. dubl iniensis from different clinical sources were chosen for comparison wi th two reference C. albicans strains. First, the distinct phylogenetic position of C. dubliniensis was further established by the comparison of the sequence of its small rRNA subunit with representative Candida species. The C. dubliniensis isolates formed true unconstricted hypha e under most induction conditions tested but failed to produce true hy phae when induced using N-acetylglucosamine, Oral C. dubliniensis isol ates were more adherent to human buccal epithelial cells than the refe rence C. albicans isolates when grown in glucose and equally adherent when grown in galactose, The C. dubliniensis isolates were sensitive t o fluconazole, itraconazole, ketoconazole and amphotericin B, Homologu es of seven tested C. albicans secretory aspartyl proteinase (SAP) gen es were detected in C. dubliniensis by Southern analysis. In vivo viru lence assays using a systemic mouse model suggest that C. dubliniensis is marginally less virulent than C. albicans, These data further conf irm the distinct phenotypic and genotypic nature of C. dubliniensis an d suggest that this species may be particularly adapted to colonizatio n of the oral cavity.