Unravelling the genetic variability of Microsporum canis
Microsporum canis is the most common dermatophyte in cats and dogs, with cats considered to be the most important reservoir hosts. M. canis is diffused worldwide and plays an important zoonotic role. Our research group has been working for years on the characterization of this fungus at a strain level. The method employed is based on a panel of 8 microsatellite markers. In time we have built a database which includes data regarding fungal isolates coming from different hosts (animals and humans) and geographical origins. Strains analyzed come prevalently from Europe (Italy, France, Germany, Austria, Belgium) and, to a lesser extent, from Egypt, Turkey, China, Korea and Brasil. The MS typing technique allowed assigning to each strain a multi-locus genotype (named “MS-Type”), associated with a serial number. Sampling sites are reported on a freely accessible “google map” document to allow an overview of the MS-Type distribution and an accession to the data “geographically-based”. Thus far, we have found a total of 91 different MS-Types from 264 samples (considered with “clone-corrected “approach), which corresponds to a genetic diversity of 96%. Some MS Types are overrepresented, which leads to hypothesize the existence of clonal lines of “major success” due to a stronger parasitic aptitude. Besides, some MS-Types appear related to specific geographical contexts (e.g MS Type 5 and 90, largely diffuse in Europe and Asia, respectively). The possible existence of genetic lineages with higher zoonotic potential is poorly supported. Indeed, considering the samples from Europe (since only in Europe we could obtain quite a balanced number of samples coming from human and animal patients) it is possible to note that a lot of MS Types were involved in human infections (45 MS Types out of 124 samples, genetic diversity 94%), with similar high genetic diversity also found in feline and canine populations.
This database and the related google map represent a useful tool for researchers aiming at work on the genetic variability of M. canis. Database and map may indeed allow the comparison of results obtained for isolates in other parts of the world.