A population genetics analysis in clinical isolates of Sporothrix schenckii based on calmodulin and calcium/calmodulin-dependent kinase partial gene sequences

Summary

Background

Sporotrichosis is a subcutaneous mycosis that is caused by diverse species of Sporothrix. High levels of genetic diversity in Sporothrix isolates have been reported, but few population genetics analyses have been documented.

Aim

To analyze the genetic variability and population genetics relations of Sporothrix schenckii Mexican clinical isolates and to compare them with other reported isolates.

Methods

We studied the partial sequences of calmodulin and calcium/calmodulin-dependent kinase genes in 24 isolates; 22 from Mexico, one fromColombia, and one ATCC^®6331^™; the latter was used as a positive control. In total, 24 isolates were analyzed. Phylogenetic, haplotype and population genetic analyses were performed with 24 sequences obtained by us and 345 sequences obtained from GenBank.

Results and conclusions

The frequency of Sporothrix schenckii sensu stricto was 81% in the 22 Mexican isolates, while the remaining 19% were Sporothrix globosa. Mexican S. schenckii sensu stricto had high genetic diversity and was related to isolates from South America. In contrast, S. globosa showed one haplotype related to isolates from Asia, Brazil, Spain and the USA. In S. schenckii sensu stricto, S. brasiliensis and S. globosa, haplotype polymorphism (θ) values were higher than the nucleotide diversity data (π). Additionally, Tajima′s D plus Fu and Li′s tests analyses displayed negative values, suggesting directional selection and arguing against the model of neutral evolution in these populations. In addition, analyses showed that calcium/calmodulin-dependent kinase was a suitable genetic marker to discriminate between common Sporothrix species.

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