Role of agglutinin-like sequence protein 3 (Als3) in the structure and antifungal resistance of Candida albicans biofilms.

Agglutinin-like sequence protein 3 (Als3) is a cell surface glycoprotein of Candida albicans that plays essential roles in the processes of adherence and biofilm formation in vitro. In this study, we focused on the contribution of Als3 to the structure and drug susceptibility of biofilms. The C. albicans wild-type (WT) strain DAY185, the als3Δ/Δ null strain and the als3Δ/Δ + pALS3 complemented strain were used. Colony-forming unit enumeration, crystal violet and cell surface hydrophobicity assays, scanning electron microscopy and confocal laser scanning microscopy coupled with analyses using COMSTAT software were performed to evaluate the biomass and architecture of the biofilms. The detailed architectural analysis showed a significant variation in the biofilm parameters of the als3Δ/Δ biofilms compared with those of the WT biofilms. Fluconazole, miconazole and amphotericin B were selected as the antifungal agents for the antimycotic susceptibility test, and increased susceptibility was found with the ALS3 deletion biofilms. A quantitative real-time polymerase chain reaction analysis showed downregulation of biofilm formation-related genes (ALS1, EFG1, HWP1 and CSH1) and drug resistance-related genes (ERG11, CDR1, CDR2 and MDR1) in the als3Δ/Δ biofilms. We concluded that Als3 contributes to biofilm formation by changing the biofilm architecture and is involved in the antifungal resistance of C. albicans biofilms.