Abstract: Objective To compare the differences of ERGI Ⅰ gene between the hyphal and yeast forms of Candida albicans.Methods Sixteen C.albicans strains(CA-1,CA-2,…CA-9,CA-11,CA-12,…CA-17),which were all isolated from a HIV-infected patient and had different sensitivity to fluconazole,were cultured in both hyphal and yeast forms.Genomic DNA was extracted from both forms of these strains.Primers were designed to amplify their ERG11 gene.The PCR products were digested by restriction endonucleases Acc Ⅰ,Mun Ⅰ and Afl Ⅱ,respectively,and after agarose gel electrophoresis,RFLP fingerprints were compared between the two forms.Meanwhile,the PCR products were sequenced with the downstream primer(P₂).Results Differences were found in the ERG11 gene between the two forms in 5 strains by both RFLP analysis and gene sequencing.The digestion of PCR products with Acc Ⅰ resulted in two fragments in the yeast form of strains CA-7 and CA-8 and in the hyphal form of strains CA-14,CA-16 and CA-17,but one fragment in the hyphal form of strains CA-7 arid CA-8 and in the yeast form of strains CA-14,CA-16 and CA-17.The RFLP pattern resulted from Mun I was coincident with that from Afl II,which presented three fragments in the yeast form of strains CA-7 and CA-8 and in the hyphal form of strains CA-14,CA-16 and CA-17,but one fragment in the hyphal form of strains CA-7 and CA-8 and in the yeast form of strains CA-14,CA-16 and CA-17.Gene sequencing revealed a C→T or T→C mutation at 1547 site,C/T→T or T→C/T mutation at 1 587 site and an A→A/G or A/G→A mutation at 1617 site,of the ERGI1 gene(GeneBank accession number:X13296) between the two forms of the five strains.Conclusion There are differences in ERGI l gene between the hyphal and yeast forms of C.albicans.

Key words: Candida albicans, Hyphas form, Yeast, ERGI l gene