[Significance of IGS1, ITS and D1/D2 regions in molecular identification of Trichosporon species and genotype of T. asahii in China].

OBJECTIVE

To compare the sensitivity and specificity in molecular identification in different DNA regions of Trichosporon species and to study the genotype of T. asahii isolated from clinical specimens in China.

METHODS

DNA was extracted from the cells of all experimental strains by using a method of glass bead method. The D1/D2, ITS and IGS1 regions were amplified by PCR with specific primers, the PCR products were cloned and sequenced. The sequences were referred to GenBank and compared with the other sequences of the Trichosporon species from GenBank by the software CLUSTAL X 1.83. Phylogenetic trees were constructed and genotypes were determined.

RESULTS

The D1/D2 regions in T. asahii (CBS2479), T. dermatis, and T. laibachii were 640, 639, and 637 bp in length respectively, the ITS regions were 541, 528, and 531 bp respectively in length, and the IGS1 regions were 643, 515, and 411 bp respectively. The sequence similarity of the D1/D2 region was 89% - 99%, that of ITS and IGS1 regions were 85% - 99% and 11% - 95% respectively. The clinically isolated strains BZP07001, BZP07002, BZP07004, and BZP07005 belonged to genotype I, and the strain BZP07003 to genotype IV.

CONCLUSION

The sensitivity and specificity of the IGS1 region was higher than those of the D1/D2 and ITS regions in identification of phylogenetically closely related Trichosporon species. T. asahii isolated from clinical specimens in China belongs to either genotype I or genotype IV.