Global Population Genetic Analysis of Aspergillus fumigatus

Abstract

The genetic diversity and geographic structure of the human fungal pathogen A. fumigatus have been the subject of many studies. However, most previous studies had relatively limited sample ranges and sizes and/or used genetic markers with low-level polymorphisms. In this paper, we characterize a global collection of strains of A. fumigatus using a panel of 9 highly polymorphic microsatellite markers. Using these markers, we analyze 2,026 isolates, which is ~3 times the number of isolates reported so far in previous studies. Our analyses suggest that A. fumigatus contains historically differentiated genetic populations but that its evolution is significantly impacted by contemporary forces such as widespread gene flow and local antifungal drug pressure. In the wake of a global rise in resistance to azoles in fungal pathogens, our findings should aid in developing management strategies to mitigate current increases to azole resistance.

Evidence of unique genetic diversity in Aspergillus fumigatus isolates from Cameroon

“…The Cameroonian samples were compared with those reported recently from other geographic regions and genetic populations . Our comparisons suggested that the Cameroonian samples of A. fumigatus are genetically different from other regions.…”

“…Here, statistical significance of the test was determined by 1000 permutations. structure software version 2.3 (Stanford, California, USA) was used for model‐based Bayesian clustering of the Cameroonian sample and those previously obtained from Eurasia, Australia, North and South America . Ancestry and allele frequency models were chosen as previously described .…”

“…Given the mobile nature of asexual A. fumigatus spores and the finding of triazole resistant strains elsewhere in Africa and outside of Africa, we expected that triazole resistance might be present in the Cameroonian environment. In addition, since A. fumigatus samples from most other geographic areas showed evidence for abundant gene flow at local, regional and continental scales, we also hypothesised that evidence for gene flow would be detected among local samples within Cameroon and between the Cameroonian samples and other geographic populations of A. fumigatus . Within Cameroon, the sampled regions were located relatively close to each other, closer than most of the reported regional samples from elsewhere that showed no genetic differentiation.…”

“…For instance, Klaassen and colleagues found up to five genetically differentiated A. fumigatus clusters in the Netherlands . A recent study by Ashu and colleagues extended the aforementioned observation by showing that A. fumigatus populations in Belgium, France, Germany, India, Norway, Spain, Switzerland and United States also contained genetically divergent strains and populations . However, at present, very little is known about the genetic diversity of African populations of A. fumigatus .…”

Host Response to Pulmonary Fungal Infections: a Highlight on Cell-Driven Immunity to Cryptococcus Species and Aspergillus fumigatus

“…Hence, advances in modern medicine have unintentionally created a niche for fungal pathogens. An additional complicating factor is the rise of drug resistant fungal strains [2–5]. In aggregate, fungal infections affect billions of people per year, worldwide, and lead to death of at least as many people as tuberculosis or malaria [6–12].…”