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Genetic variation associated with infection and the environment in the accidental pathogen Burkholderia pseudomallei
Claire Chewapreecha1,2,3,4, Alison E Mather5,6, Simon R Harris3
11Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand.
Abstract:
The environmental bacterium Burkholderia pseudomallei causes melioidosis, an important endemic human disease in tropical and sub-tropical countries. This bacterium occupies broad ecological niches including soil, contaminated water, single-cell microbes, plants and infection in a range of animal species. Here, we performed genome-wide association studies for genetic determinants of environmental and human adaptation using a combined dataset of 1,010 whole genome sequences of B. pseudomallei from Northeast Thailand and Australia, representing two major disease hotspots. With these data, we identified 47 genes from 26 distinct loci associated with clinical or environmental isolates from Thailand and replicated 12 genes in an independent Australian cohort. We next outlined the selective pressures on the genetic loci (dN/dS) and the frequency at which they had been gained or lost throughout their evolutionary history, reflecting the bacterial adaptability to a wide range of ecological niches. Finally, we highlighted loci likely implicated in human disease.
Insights
This study identifies genetic factors in Burkholderia pseudomallei, the cause of melioidosis, that help it adapt to diverse environments and cause human disease. Researchers pinpointed key genes linked to clinical and environmental strains in Thailand and Australia.
Area of Science:
- Microbiology
- Genomics
- Evolutionary Biology
Background:
- Melioidosis is a significant human disease caused by the environmental bacterium Burkholderia pseudomallei.
- This bacterium thrives in various ecological niches, including soil, water, plants, and animals, in tropical and subtropical regions.
- Understanding the genetic basis of B. pseudomallei's adaptation is crucial for public health in endemic areas.
Purpose of the Study:
- To identify genetic determinants associated with environmental and human adaptation in Burkholderia pseudomallei.
- To investigate the evolutionary pressures and gene gain/loss events shaping the bacterium's adaptability.
- To highlight specific genetic loci potentially involved in human melioidosis.
Main Methods:
- Genome-wide association studies (GWAS) were conducted on a dataset of 1,010 whole genome sequences of B. pseudomallei.
- Isolates were sourced from two major disease hotspots: Northeast Thailand and Australia.
- Analysis included selective pressure assessment (dN/dS) and evolutionary history of genetic loci.
Main Results:
- 47 genes from 26 distinct loci were associated with clinical or environmental isolates from Thailand.
- 12 of these genes were successfully replicated in an independent Australian cohort.
- Selective pressures and gene dynamics revealed significant bacterial adaptability across ecological niches.
Conclusions:
- The study identified key genetic loci contributing to B. pseudomallei's adaptation to diverse environments and its pathogenicity.
- These findings provide insights into the evolution of melioidosis-causing strains.
- Specific highlighted loci are likely implicated in the development of human melioidosis, offering potential targets for future research or intervention.