交配型遺伝子解析から考える皮膚糸状菌の分類について

Abstract

Trichophyton mentagrophytes is epidemiologically divided into two distinct forms, zoophilic and anthropophilic. The zoophilic isolates of T.mentagrophytes have generally been identified by morphological and biochemical examination as well as through mating experiments. The confirmed teleomorphs of the zoophilic isolates of the T.mentagrophytes complex are Arthroderma benhamiae, A. simii and A. vanbreuseghemii. On the other hand, no teleomorph has been identified in an anthropophilic isolate of T. mentagrophytes, such as T. mentagrophytes var. interdigitale (T. interdigitale) or in the other anthropophilic strains. In the present study, the mating type (MAT) (-)-specific gene of the MAT1-1 (alpha-box) and the MAT (+)-specific gene of the MAT1-2 (high-mobility-group : HMG) DNA binding domain were confirmed in zoophilic dermatophytes of A. benhamiae, A. simii and A. vanbreuseghemii. The sequence of the MAT1-1 was about 1.3 kbp, containing 2 exons in the A. benhamiae, A. simii and A. vanbreuseghemii (-) mating type strain. The sequence of the MAT1-2 was 1.9 kbp, containing 2 exons in the A. benhamiae, A. simii and A. vanbreuseghemii (+) mating type strain. Of 15 animal isolates and 72 human isolates examined, the MAT1-1 was detected in 5 of the animal isolates and in none of the human isolates, while the MAT1-2 was detected in the other 10 of the animal isolates and in all of the human isolates. These results indicate that anthropophilic T. mentagrophytes evolved from the A. vanbreuseghemii (+) mating strain.