TY - JOUR
T1 - Dating the Cryptococcus gattii dispersal to the North American Pacific Northwest
AU - Roe, Chandler C.
AU - Bowers, Jolene
AU - Oltean, Hanna
AU - DeBess, Emilio
AU - Dufresne, Philippe J.
AU - McBurney, Scott
AU - Overy, David P.
AU - Wanke, Bodo
AU - Lysen, Colleen
AU - Meyer, Tom Chillerh Wieland
AU - Thompson, George R.
AU - Lockhart, Shawn R.
AU - Hepp, Crystal M.
AU - Engelthaler, David M.
N1 - Funding Information:
We thank all our colleagues from around the world who have contributed isolates to either the current or previously published Cryptococcus whole-genome studies. This analysis was supported by the Centers for Disease Control and Prevention (contract no. 200201461029 to D.M.E.), NIH (grant number R21AI098059 to D.M.E., G.R.T., S.R.L. and W.M.), and an Australian NH&MRC grant (grant number APP1031943 to W.M.). The findings and conclusions in the manuscript are those of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention
Publisher Copyright:
© 2018 Roe et al.
PY - 2018/1/1
Y1 - 2018/1/1
N2 - The emergence of Cryptococcus gattii, previously regarded as a predominantly tropical pathogen, in the temperate climate of the North American Pacific Northwest (PNW) in 1999 prompted several questions. The most prevalent among these was the timing of the introduction of this pathogen to this novel environment. Here, we infer tip-dated timing estimates for the three clonal C. gattii populations observed in the PNW, VGIIa, VGIIb, and VGIIc, based on whole-genome sequencing of 134 C. gattii isolates and using Bayesian evolutionary analysis by sampling trees (BEAST). We estimated the nucleotide substitution rate for each lineage (1.59 × 10-8, 1.59 × 10-8, and 2.70 × 10-8, respectively) to be an order of magnitude higher than common neutral fungal mutation rates (2.0 × 10-9), indicating a microevolutionary rate (e.g., successive clonal generations in a laboratory) in comparison to a species' slower, macroevolutionary rate (e.g., when using fossil records). The clonal nature of the PNW C. gattii emergence over a narrow number of years would therefore possibly explain our higher mutation rates. Our results suggest that the mean time to most recent common ancestor for all three sublineages occurred within the last 60 to 100 years. While the cause of C. gattii dispersal to the PNW is still unclear, our research estimates that the arrival is neither ancient nor very recent (i.e., < 25 years ago), making a strong case for an anthropogenic introduction.
AB - The emergence of Cryptococcus gattii, previously regarded as a predominantly tropical pathogen, in the temperate climate of the North American Pacific Northwest (PNW) in 1999 prompted several questions. The most prevalent among these was the timing of the introduction of this pathogen to this novel environment. Here, we infer tip-dated timing estimates for the three clonal C. gattii populations observed in the PNW, VGIIa, VGIIb, and VGIIc, based on whole-genome sequencing of 134 C. gattii isolates and using Bayesian evolutionary analysis by sampling trees (BEAST). We estimated the nucleotide substitution rate for each lineage (1.59 × 10-8, 1.59 × 10-8, and 2.70 × 10-8, respectively) to be an order of magnitude higher than common neutral fungal mutation rates (2.0 × 10-9), indicating a microevolutionary rate (e.g., successive clonal generations in a laboratory) in comparison to a species' slower, macroevolutionary rate (e.g., when using fossil records). The clonal nature of the PNW C. gattii emergence over a narrow number of years would therefore possibly explain our higher mutation rates. Our results suggest that the mean time to most recent common ancestor for all three sublineages occurred within the last 60 to 100 years. While the cause of C. gattii dispersal to the PNW is still unclear, our research estimates that the arrival is neither ancient nor very recent (i.e., < 25 years ago), making a strong case for an anthropogenic introduction.
KW - Cryptococcus
KW - Genomics
KW - Molecular epidemiology
KW - Mycology
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U2 - 10.1128/mSphere.00499-17
DO - 10.1128/mSphere.00499-17
M3 - Article
C2 - 29359190
AN - SCOPUS:85041503648
SN - 2379-5042
VL - 3
JO - mSphere
JF - mSphere
IS - 1
M1 - e00499-17
ER -