Evolutionary processes in populations of Cryptosporidium inferred from gp60 sequence data

Area of Science:

• Molecular Epidemiology
• Parasitology
• Population Genetics

Background:

• Cryptosporidiosis is a globally prevalent protozoan infectious disease.
• The gp60 gene is crucial for characterizing Cryptosporidium genotypes and variants in human infections.
• Limited understanding exists regarding spatial-temporal demographic variations and selective pressures on the gp60 gene.

Purpose of the Study:

• To analyze genetic variation in Cryptosporidium populations over time and space in New Zealand.
• To infer the underlying processes driving sequence polymorphism patterns.
• To distinguish between distinct population processes and detect simultaneous effects.

Main Methods:

• Analysis of genetic variation within two putative Cryptosporidium populations.
• Application of neutrality tests (Tajima's D, Fu, and Li's D* and F*).
• Demographic analyses to infer population dynamics and recombination rates.

Main Results:

• Significant departures from neutrality were observed in some populations.
• Evidence suggests selective maintenance of alleles within certain populations.
• High recombination rates and population expansion distorted genetic variability patterns, correlating with case notification data.

Conclusions:

• Distinct population processes, even with similar effects, can be differentiated.
• Multiple evolutionary processes can act concurrently on parasite populations.
• Findings are significant for predicting parasite dynamics and understanding long-term changes in cryptosporidiosis risk.