Molecular characterization of dermatophytes isolated from cattle in Plateau State, Nigeria

Abstract

Dermatophytes from cattle were successfully characterized to species and strain levels for the first time in Nigeria. This study was undertaken to isolate and characterize dermatophytes from cattle in Plateau State, Nigeria. Two molecular techniques were utilized. The first was the use of polymerase chain reaction (PCR) to amplify the internal transcribed spacer regions of the ribosomal DNA using ITS-1 and ITS-4 as primers. This was followed by restriction fragment length polymorphism analysis of the amplified ITS regions using the enzyme MvaI to identify dermatophyte species. The second technique was a PCR using the short oligonucleotide 5'-GACAGACAGACAGACA-3' as primer for the RAPD typing of the isolates for identification of dermatophytes based on species specific profiles. Profiles of dermatophytes and their correlation with location, site of infection and severity of disease were also investigated. Both PCR-RFLP and RAPD analysis identified 26 Trichophyton verrucosum and 22 Trichophyton mentagrophytes. The PCR-RFLP analysis of the ITS regions produced two distinct profiles for both T. mentagrophytes and T. verrucosum. The first Profile for T. mentagrophytes consisted of two fragments of approximately 320 bp and 280 bp in length while the second was approximately 350 bp and 250 bp in length. The first profile for T. verrucosum consisted of two fragments having bands of approximately 380 bp and 220 bp. The second profile had a single band of undigested fragment of approximately 600 bp in length. Both T. mentagrophytes and T. verrucosum yielded identifiable fragments by RAPD analysis. Six profiles were produced for T. mentagrophytes and the PCR finger prints ranged from 1 to 9 bands with sizes ranging from approximately 350 to 5000 base pairs in size. Amplification of T. verrucosum isolates produced four Profiles. The PCR fingerprints ranged from 5 to 7 bands with sizes ranging from 500 bp-5000 bp. The results indicate that differences in location could contribute to variations in PCR amplicons of dermatophytes and strain differences in dermatophytes may be responsible for variation in clinical dermatophytosis but no significant association was observed between profiles of dermatophytes and the site of infection. The PCR-RFLP analysis of the internal transcribed spacer regions using the primer set ITS1/ITS4 and RAPD analysis using (GACA)₄ as primer were successfully used to accurately identify dermatophytes from cattle to species and strain levels. Few molecular studies targeting dermatophytes of cattle are available in the literature. As far as we know, this may be the first report of molecular characterization of cattle dermatophytes from Africa.

Keywords: Cattle; Characterization; Dermatophytes; Nigeria; Plateau State.