Identification of CSP Types and Genotypic Variability of Clinical and Environmental Isolates of Aspergillus fumigatus from Different Geographic Origins.

Esperanza Duarte-Escalante,María Del Rocío Reyes-Montes,Emmanuel Rosas De Paz,Erick Martínez-Herrera,María Guadalupe Frías-De-León,Nicolás Refojo,Jesús Reséndiz-Sánchez,Gustavo Acosta-Altamirano

doi:10.3390/microorganisms8050688

Abstract

The CSP (cell surface protein) microsatellite marker is useful for typing Aspergillus fumigatus isolates and determining relationships at the subpopulation level because it has shown high discriminatory power. In the present study, 90 A. fumigatus isolates from Mexico (MX), Argentina (AR), France (FR), and Peru (PE) were identified through a phylogenetic analysis using the benA gene fragment and were typed with the CSP microsatellite, and the types were identified using the nomenclature recommended in the literature. Genetic variability was analyzed through haplotype diversity, nucleotide diversity, polymorphic sites, and nucleotide differences between pairs of sequences. The population structure was evaluated using the Tajima’s D statistic. No new CSP types were recorded in the MX, FR, and PE isolates, while in the AR isolates, two new CSP types were identified (t25 and t26). The most common CSP types in the studied populations were t01, t02, t03, and t04A; these results are consistent with findings in other countries. In addition, the genetic diversity parameters we obtained revealed that the greatest genetic diversity was found in the MX population, followed by AR and FR. No population structure was identified among the isolates studied.

Highlights

Aspergillosis is caused by fungi of the genus Aspergillus, which contains etiological agents that are capable of causing different clinical forms of the disease in humans, of which invasive aspergillosis is the most severe form [1]
The 90 isolates were identified as A. fumigatus according to their phenotypic characteristics, and they exhibited macroscopic and microscopic morphological characteristics reported for the Fumigati section
To determine A. fumigatus species, a phylogenetic analysis was performed with the sequences of the benA gene fragment from all isolates studied

Summary

Introduction

Aspergillosis is caused by fungi of the genus Aspergillus, which contains etiological agents that are capable of causing different clinical forms of the disease in humans, of which invasive aspergillosis is the most severe form [1]. The classification of the genus Aspergillus consists of four subgenera: Aspergillus (with two sections), Circumdati (with six sections), Fumigati (with three sections), and Nidulantes (with 10 sections) [5,6], with a total of 339 accepted species [7]; cryptic species continue to be detected that are difficult to differentiate from related species For this reason, PCR-based molecular methods are used, using sequencing of gene fragments such as 18S rRNA, mitochondrial DNA, rodlet A (rodA), β-tubulin (benA, tub-2), actin (Act), calmodulin (caM), and internal transcribed spacer regions (ITS) [8,9] for identification at the species level. For identification at the species level, other markers such as benA, tub-2, and caM, which are crucial genes in the Aspergillus taxonomy, can be used in combination with the ITS region [10]

Methods

Results

Discussion

Conclusion