Population genetic structure of clinical and environmental isolates of Blastomyces dermatitidis based on 27 polymorphic microsatellite markers

Applied and Environmental Microbiology
By: , and 

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Abstract

Blastomyces dermatitidis, a thermally dimorphic fungus, is the etiologic agent of North American blastomycosis. Clinical presentation is varied, ranging from silent infections to fulminant respiratory disease and dissemination to skin and other sites. Exploration of the population genetic structure of B. dermatitidis would improve our knowledge regarding variation in virulence phenotypes, geographic distribution, and difference in host specificity. The objective of this study was to develop and test a panel of microsatellite markers to delineate the population genetic structure within a group of clinical and environmental isolates of B. dermatitidis. We developed 27 microsatellite markers and genotyped B. dermatitidis isolates from various hosts and environmental sources (n=112). Assembly of a neighbor-joining tree of allele-sharing distance revealed two genetically distinct groups, separated by a deep node. Bayesian admixture analysis showed that two populations were statistically supported. Principal coordinate analysis also reinforced support for two genetic groups, with the primary axis explaining 61.41% of the genetic variability. Group 1 isolates average 1.8 alleles/locus, whereas group 2 isolates are highly polymorphic, averaging 8.2 alleles/locus. In this data set, alleles at three loci are unshared between the two groups and appear diagnostic. The mating type of individual isolates was determined by PCR. Both mating type-specific genes, the HMG and α-box domains, were represented in each of the genetic groups, with slightly more isolates having the HMG allele. One interpretation of this study is that the species currently designated B. dermatitidis includes a cryptic subspecies or perhaps a separate species.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Population genetic structure of clinical and environmental isolates of Blastomyces dermatitidis based on 27 polymorphic microsatellite markers
Series title Applied and Environmental Microbiology
DOI 10.1128/AEM.00258-11
Volume 77
Issue 15
Year Published 2011
Language English
Publisher American Society for Microbiology
Contributing office(s) Coop Res Unit Leetown
Description 9 p.
First page 5123
Last page 5131
Online Only (Y/N) N
Additional Online Files (Y/N) N