Molecular identification of species, varieties, genotypes and mating types of Cryptococcus neoformans species complex

Abstract

Objective To evaluate the role of Restriction fragment length polymorphism (RFLP) analysis in detection of the fragment of GEF1α/a gene which are both located at ct and a mating type loci in identification of species, varieties, genotypes and mating types of Cryptococcus neoformans species complex(Cryptococcus neoformans and Cryptococcus gattii). Methods The GEF1α/a gene was selected from 20 genes which both located at α and a mating type loci for RFLP analysis, according to the requirements of sequence similarities and primer design in PCR-RFLP analysis. Primer pair was designed from the conserved regions of GEF1α/a genes of distinct genotypes and mating types of reference strains to amplify a fragment of GEF1α/a gene from Cryptococcus neoformans and Cryptococcns gattii strains tested. Sequence alignment,restriction maps analysis, endonucleases selection and electrophoresis stimulation were conducted by using DNAMAN and Vector NTI software. EeoT14 Ⅰ and Hap Ⅱ endonucleases were selected for RFLP analysis of the GEF1α/a fragments amplified from 125 isolates of Cryptococcns neoformans and Cryptococcus gattii. Results An approximate 1 300 bp fragment was amplified from total 82 Cryptococcus neoformans and 43 Cryptoceccus gattii isolates. However, negative PCR results were found in the reference strains of Cryptococcus laurentii, Candida albicans, Candida tropicalis, Candida parapsilosis, Candida krnsei,Candida glabrata, Trichosporon asahii, Aspergillus fumigatns and Aspergillus flavus. RFLP analysis successfully identified the species, varieties, genotypes and mating types of total 125 isolates of Cryptococcus neoformans and Cryptococcns gattii tested in this study. Condusion PCR-RFLP analysis of the GEF1α/a fragment has the potential value in identification of species, varieties, genotypes and mating types of Cryptococeus neoformans species complex simultaneously and rapidly, and may be a useful tool in molecular epidemiological analysis. Key words: Cryptococcus; Genotype; Genes,fungal; Polymorphism,restriction fragment length