Abstract: Objective · To construct the ERG3 gene knockout strain of Candida albicans, and to analyze the effect of ERG3 knockout on the resistance of Candida albicans to azole drugs and the of its common resistance genes. Methods · Knockout components were constructed with genomic DNA of Candida albicans SN152 and plasmid DNA with screening markers as templatesfusion PCR and homologous recombination techniques. The knockout components were transfected into Candida albicans SN152lithium acetate transfection method to obtain ERG3+/- and ERG3-/- strains. The differences of drug resistance in SN152, ERG3+/- and ERG3-/- strains to azole drugs were determinedmicrobroth dilution method. Meanwhile, real-time quantitative PCR (qPCR) was used to detect the of drug resistance-related genes in the three strains. Results · Candida albicans ERG3 gene knockout strains were efficiently constructed. The resistance of ERG3-/- strains to azole drugs was significantly higher than that of ERG3+/- and SN152 strains. The of drug resistance-related genes (CDR1, CDR2, MDR1, ERG11) in ERG3-/- strains increased significantly (all PConclusion · Candida albicans SN152 ERG3-/- double allelic knockout strain is successfully constructed. The knockout of ERG3 gene improves the resistance of Candida albicans to azole drugs, and the down-regulation of ERG3 gene is accompaniedthe up-regulation of other resistance related genes.

Key words: Candida albicans, ERG3 gene, gene knockout, drug resistance