Haplotypic variability within the mitochondrial gene encoding for the cytochrome c oxidase 1 (cox1) of Cylicocyclus nassatus (Nematoda, Strongylida): evidence for an affiliation between parasitic populations and domestic and wild equid hosts.

This research presents a study on the genetic variability within a particular parasite found in both domestic and wild horses and highlights potential implications for studying the genetic structure of such parasites and understanding anthelmintic resistance.

Study Objectives and Methods

• The research undertook an investigation into the genetic diversity of Cylicocyclus nassatus, a type of nematode, or worm, often found in equine species such as horses, donkey, and certain types of wild horses like tarpans and Turkmen kulans.
• Equines from different locations in Europe and the USA were sampled for this study.
• The study focused on two genetic regions of the worm: the Internal Transcribed Spacer 2 (ITS2) and a mitochondrial gene known as cytochrome c oxidase subunit 1 (cox1).
• Seventy individual parasitic specimens were collected, and their ITS2 and cox1 gene sequences were PCR-amplified and characterized using genetic sequencing techniques.

Study Findings

• Low genetic variation (0-0.6%) was observed in the ITS2 gene among all individual adult specimens of C. nassatus.
• Contrarily, twenty-two different sequence variants or haplotypes of the cox1 gene were discovered.
• These cox1 variations occurred at a significant rate of 10.8% at 75 out of 689 nucleotide positions analyzed.
• Interestingly, no consistent patterns were found among specimens collected from each equid species or country, suggesting considerable genetic diversity within the parasite’s population.
• However, two distinct haplotypes were identified specifically in horses from the USA and donkeys in Italy and Ukraine.
• Consequently, none of the haplotypes were shared across the different equine species, indicating a potential link between the parasite populations and their specific hosts.

Implications

• The observed genetic diversity within the cox1 gene of C. nassatus could be crucial in studying the genetic structure and biology of similar parasites (cyathostomes) occurring in equine species.
• This could help in addressing taxonomic issues related to such equine parasites.
• The findings also carry practical implications for understanding the spread of anthelmintic resistance, a global problem impacting the effective control of parasitic worms in animals.