Phylogenetic Study On Causitive Agents Of Tinea Capitis In Xinjiang

Objective: To clarify the phylogenetic characteristics of four causitive agents of tinea capitis in Xinjiang,namely Trichophyton schoenleinii,Trichophyton tonsurans,Trichophyton violaceum and Microsporum canis in order to provide data support for the cause of the high prevalence of tinea capitis in Xinjiang from the perspective of strain evolution.Methods: Causitive agents of tinea capitis were collected from dermatology laboratory of the First Affiliated Hospital of Xinjiang Medical University.The isolated patients were from urumqi and karamay in northern xinjiang,and kashgar and hotan in southern xinjiang.The clinical strains used in the experiment were cultured on potato PDA medium at 27 C.The genomic DNA of the cultivated strain was extracted.The ITS primers and Beta-tublin intergenic sequences were amplified by ordinary PCR.The PCR products were detected by gel electrophoresis and then sequenced.The data were compared with blast homologous sequences in GenBank nucleicacid database.According to blast homology comparison results,the reference strain information with the highest degree of homology was selected.Clustal and MEGA5.0 were used to align the sequences,and 500 bootstrap statistical tests were performed to plot phylogenetic trees of ITS and beta-tubulin gene sequences of the four strains.Results:The ITS and beta-tublin sequences of the four strains were completely consistent with morphological identification.The use of beta-tublin interzones is more reliable than that of ITS interzones in the study of fungal phylogeny,and the interspecific homology is up to 100%.Conclusion:Based on the system analysis of characteristics of the phylogenetic trees of four kinds of causitive agents and the genetic relationship between the reference strains,respectively showes xinjiang local Trichophyton violaceum and other Trichophyton violaceum reference strains which from Iran,Japan,Greece and India gathered within a cluster,indicates that they have a high degree ofkinship,the nearest reference strains from Iran KT192547.1,suggests they were closely related to each other.The Microsporum canis belonged to one main part with those from Iran,Vietnam,New Zealand,Aionia and India,indicating that they had a high degree of kinship,among which the local strain was closest to the reference strain KU496912.1from India,indicating that the two were closest to each other.Trichophyton schoenleinii and the reference strains from Iran,Russia,Australia and China clustered in the same cluster,indicating that these strains were related to each other,but the genetic distance between the local strains and the reference strains was far,indicating that there were some differences between the local strains and the reference strains.Conclusion: The four causitive agents of xinjiang tinea capitis were related to the reference strains from different regions,among which the local Trichophyton violaceum was the closest to the strains from Iran KT192547.1.Microspore Canis is the closest relative to the strain from India KU496912.1.Although Trichophyton schoenleinii is related to the reference strains of the same genus,its distant relationship indicates that it is different from other reference strains,and Trichophyton tonsurans also shows the same phylogenetic characteristics.