Use of Population Genetics to Assess the Ecology, Evolution, and Population Structure ofCoccidioides

Abstract

Although Coccidioides genotypes are highly genetically variable, they cluster into discrete populations, which has implications for human infections.

Coccidioides immitis and posadasii; A review of their biology, genomics, pathogenesis, and host immunity

“…They cannot be distinguished by serologic tests, but the two species can be distinguished by genetic polymorphisms, and some differences in growth characteristics have been reported [4,5]. C. posadasii has a larger population size, which is more diverse than C. immitis [6]. The biggest difference between the two species is their geographic distribution.…”

“…The biggest difference between the two species is their geographic distribution. C. immitis is primarily found in the desert regions of Central and Southern California (including Baja California), while C. posadasii is primarily found in desert regions of Nevada, Arizona, New Mexico, West Texas, Mexico, and Central and South America implying that were significant geographic barriers at the time the species diverged from a common ancestor [6]. Some geographic overlap between the two species also occurs in Southern California and Baja California [7].…”

“…There is some hybridization between the two species [6,35]. Sequencing of a large number of clinical isolates in Arizona established that almost all were genetically diverse strains of C. posadasii [8].…”

“…Groups of isolates from Tucson and Phoenix areas are genetically distinct. A study comparing soil isolates from Phoenix to isolates from patients in the same area found that the environmental isolates were more genetically diverse than the clinical isolates, but there was no evidence for a subset of more pathogenic strains that might explain the increasing incidence of infections in that area [6,34]. …”

The Powers and Perils of PCR in the Search for the Natural Reservoirs of Coccidioides Species

“…In a recent study, Teixeira and Barker hypothesized the existence of two subpopulations of C. immitis in central and southern California and three subpopulations of C. Posadasii in Arizona, Mexico, and Texas/South America by analyzing 495 clinical and environmental isolates [32]. We believe that the availability of more environmental isolates across large spatial scales will be crucial for future WGS studies.…”