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Application of a new PCR-RFLP panel suggests a restricted population structure for Eimeria tenella in UK and Irish chickens

Pegg, Elaine, Doyle, Kate, Clark, Emily L., Jatau, Isa D., Tomley, Fiona M., Blake, Damer P.
Veterinary parasitology 2016 v.229 pp. 60-67
Eimeria tenella, broiler chickens, coccidiosis, coccidiostats, cost effectiveness, data collection, drug resistance, epidemiology, genetic variation, genotyping, haplotypes, parasites, polymerase chain reaction, population structure, poultry production, production technology, restriction fragment length polymorphism, single nucleotide polymorphism, vaccines, Africa, Asia, Ireland, United Kingdom
Eimeria species cause coccidiosis, most notably in chickens where the global cost exceeds US$3 billion every year. Understanding variation in Eimeria population structure and genetic diversity contributes valuable information that can be used to minimise the impact of drug resistance and develop new, cost-effective anticoccidial vaccines. Little knowledge is currently available on the epidemiology of Eimeria species and strains in different regions, or under different chicken production systems. Recently, 244 Eimeria tenella isolates collected from countries in Africa and Asia were genotyped using a Sequenom single nucleotide polymorphism (SNP) tool, revealing significant variation in haplotype diversity and population structure, with a marked North/South regional divide. To expand studies on genetic polymorphism to larger numbers of E. tenella populations in other geographic regions a cheaper and more accessible technique, such as polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), is desirable. We have converted a subset of SNP markers for use as PCR-RFLPs and re-analysed the original 244 isolates with the PCR-RFLPs to assess their utility. In addition, application of the PCR-RFLP to E. tenella samples collected from UK and Irish broiler chickens revealed a tightly restricted haplotype diversity. Just two of the PCR-RFLPs accounted for all of the polymorphism detected in the UK and Irish parasite populations, but analysis of the full dataset revealed different informative markers in different regions, supporting validity of the PCR-RFLP panel. The tools described here provide an accessible and cost-effective method that can be used to enhance understanding of E. tenella genetic diversity and population structure.