Molecular identification and mitogenomic characterization of cattle-associated Trichophyton verrucosum-related isolates from Kazakhstan

Abstract

Dermatophytosis caused by zoophilic Trichophyton species remains an important infectious skin disease in cattle, but molecular data on veterinary dermatophytes from Central Asia are limited. This study characterized cattle-associated Trichophyton verrucosum-related isolates obtained from Kazakhstan using conventional mycology, experimental pathogenicity assessment, ITS-based phylogenetic analysis, and mitochondrial genome characterization. Twelve field Trichophyton isolates from six regions of Kazakhstan were examined. Cattle showed circumscribed alopecic and crusted skin lesions compatible with dermatophytosis, and fungal isolation was performed using affected hair and skin scales. In a rabbit scarified-skin model, isolates KZ_Tr1 and KZ_Tr2 from the Almaty region showed the highest lesion involvement among the tested field isolates, reaching 40, 60, and 80% at 3.0 × 106, 5.0 × 106, and 8.0 × 106 microconidia/cm3, respectively. These two isolates were selected for molecular and mitogenomic analysis. ITS sequences of KZ_Tr1 and KZ_Tr2 clustered within a T. verrucosum-related lineage, although species-level interpretation was treated cautiously because the analysis was based on a single rDNA/ITS marker. Illumina sequencing enabled reconstruction of circular mitochondrial assemblies of 24,216 bp for KZ_Tr1 and 24,317 bp for KZ_Tr2. KZ_Tr2 showed stronger assembly quality metrics, including complete genome coverage, higher read depth, and fewer ambiguous nucleotide positions, and was therefore used as the main mitochondrial genome for detailed interpretation. Annotation of KZ_Tr2 identified 16 protein-coding genes, 24 tRNA genes, one small-subunit rRNA gene, and three tandem repeats. These findings provide the first molecular and mitochondrial genome data for cattle-associated T. verrucosum-related isolates from Kazakhstan and establish a regional baseline for future epidemiological, diagnostic, and comparative genomic studies of veterinary dermatophytes.