Abstract:

Objective To assess the subgenotypes of pathogenic Cryptococcus gattii isolates from China and to elucidate the epidemiological links between these domestic isolates and those from other parts of the world. Methods DNA was extracted from 9 clinical isolates of Cryptococcus gattii from China. The partially variable regions of the three unlinked loci, namely IGS1, PLB1 and GEF1, were amplified and sequenced, and the bioinformation at these loci was obtained from GenBank for multi-locus sequences alignment and phylogenetic analysis. Results Of these 9 clinical isolates, 8 were genotype VGⅠ and mating type α with the same sequences at the tested regions as the reference strain WM276, which was a representative isolate of an independent subgenotype; 1 was of genotype VGⅡ and mating type α, which was the first report in China, with the tested sequences consistent with those of the referrence strain R272. Sequencing and phylogenetic analysis of GEF1 gene, which was located at mating type locus, successfully identified the genotypes and mating types of all the Cryptococcus gattii isolates involved here. Conclusions Multi-locus sequence analysis shows that causative Cryptococcus gattii isolates of genotype VGⅠ in China carry similar sequences at the tested loci in IGS1, PLB1 and GEF1 genes, to a widely distributed subgenotype in the world, and the sequences of the first VGⅡ genotype isolate from China resemble the less virulent subgenotype VGⅡb found in Vancouver islands.

Key words: Cryptococcus gattii;Subgenotype;Mating type;Phylogenetic analysis