Coccidioides Species Determination: Does Sequence Analysis Agree with Restriction Fragment Length Polymorphism?

Abstract

Fifteen Coccidioides isolates were previously examined for genetic diversity using restriction fragment length polymorphism (RFLP); two fragment patterns were observed. Two isolates demonstrated one banding pattern (designated RFLP group I), while the remaining 13 isolates demonstrated a second pattern (designated RFLP group II). Recently, molecular studies supported the division of the genera Coccidioides into two species: Coccidioides posadasii and Coccidioides immitis. It has been assumed that the species division corresponds to the RFLP grouping. We tested this hypothesis by amplifying the ribosomal DNA internal transcribed spacer region as well as the dioxygenase, serine proteinase, and urease genes from 13 isolates previously examined by RFLP and then sequencing the PCR products. The appropriate species for each isolate was assigned using phylogenetically informative sites. The RFLP grouping agreed with the Coccidioides species assignment for all but one isolate, which may represent a hybrid. In addition, polymorphic sites among the four genes examined were in agreement for species assignment such that analysis of a single gene may be sufficient for species assignment.

Unravelling species boundaries in the Aspergillus viridinutans complex (section Fumigati): opportunistic human and animal pathogens capable of interspecific hybridization

“…(Schröder et al 2016), Malassezia spp. (Wu et al 2015), Cryptococcus neoformans and C. gattii (Bovers et al 2006, 2008, Kwon-Chung & Varma 2006, Aminnejad et al 2012) and Coccidioides immitis and C. posadasii (Johnson et al 2015). However, to date, reports on these hybrids in filamentous fungi are restricted to the Neocosmospora solani complex (Short et al 2013, 2014).…”

Hybridization and emergence of virulence in opportunistic human yeast pathogens

“…Although not being a dangerous disease in immunocompetent patients, it is estimated that 150 000 new cases of coccidioidomycosis occur annually in the USA, of which one‐third are fatal, being a special concern for immunocompromised persons (Odio et al, ). Genomic analyses of some populations from both species revealed the presence of a recent hybridization event (Neafsey et al, ), and more recently, the analysis of some genetic markers uncovered again the presence of hybrid organisms in these populations (Johnson et al, ). For instance, the genomic patterns of introgression between these two species revealed that at least 8% of the genes in C. immitis population may have been recently introgressed from C. posadasii , presenting an enrichment in genes associated with immune evasion and cell walls (Neafsey et al, ).…”