Identification of Cryptococcus neoformans var. grubii, var. neoformans and Cryptococcus gattii by multiplex PCR.

Objective To establish a multiplex PCR targeting the intergenic spacer regions (IGS) for the identification of Cryptococcus neoformans var.grubii,var.neoformans and Cryptococcus gattii.Methods Primers were designed by using the software ClustalW2 and Oligo 6 based on the sequence of IGS1 region,which shows high sequence variability in the genome of Cryptococcus neoformans and Cryptococcus gattii.,for the multiplex PCR.Then,the developed multiplex PCR was performed to identify 51 Cryptococcus neoformans strains representing genotypes VNI-VNIV and VNB as well as 41 Cryptococcus gattii strains representing genotypes VGI-VGIV.The identification results were compared with those from common PCR by using primers GPA1A,CLA4D and SODlgattii specific to Cryptococcus neoformans var.grubii,var.neoformans and Cryptococcus gattii,respectively,as well as with those from the canavanine-glycine-bromothymol blue (CGB) medium-based culture.Results The developed multiplex PCR successfully identified the 92 Cryptococcus neoformans and Cryptococcus gattii.strains,and yielded negative results from the other tested pathogenic yeasts,which revealed a high specificity of the designed primers.False positive results were observed in the identification of two Cryptococcus gattii strains with GPA1A primer-based PCR,one Cryptococcus gattii strain with CLA4D primer-based PCR,one var.grubii strain and one var.neoformans strain with CGB culture,while no false negative results were observed in the detection of these Cryptococcus strains by any of these methods.Conclusions The developed multiplex PCR in this study can rapidly and accurately identify Cryptococcus neoformans var.grubii,var.neoformans,AD hybrid,and Cryptococcus gattii,with superior performance in comparison with common PCR and CGB medium-based culture. Key words: Cryptococcosis;  Polymerase chain reaction;  Genotype