A PCR-ELISA for the identification of cyathostomin fourth-stage larvae from clinical cases of larval cyathostominosis.

The given study presents the utilization of a Polymerase Chain Reaction- Enzyme Linked Immunosorbent Assay (PCR-ELISA) technique and specifically designed oligoprobes to identify fourth-stage larvae (L4) of parasitic Cyathostomin species from horses with clinical larval cyathostominosis, a common and serious parasitic disease in equines.

Study Objective and Methodology

The research paper describes the use of a PCR-ELISA technique to detect and identify Cyathostomin larvae at their fourth stage (L4) from samples collected from horses suffering from clinical larval cyathostominosis. The research has employed six uniquely designed oligoprobes that target the intergenic spacer region sequences of the parasites’ DNA.
The following species are identified using the respective oligoprobes:

• Cylicocyclus ashworthi
• Cylicocyclus nassatus
• Cylicocyclus insigne
• Cyathostomum catinatum
• Cylicostephanus goldi
• Cylicostephanus longibursatus

An additional seventh probe was designed as a positive control to identify all these members of the Cyathostominae family.

Research Process

The PCR amplification of the intergenic spacer region was done using conserved primers. To start with, three oligoprobes were utilized for a Southern blot analysis. Afterwards, to expedite the identification process, these and four more oligoprobes were developed and deployed using a PCR-ELISA technique. Each probe’s efficiency was validated by its ability to detect cyathostomin PCR products using DNA from adult parasites identified based on morphology.

Collection and Analysis

The initial isolation resulted in 712 L4 samples from the diarrhoeic excreta of 17 horses with clinical larval cyathostominosis. The PCR products from 522 L4 samples were then subjected to PCR-ELISA tests, whereby 413 samples were identified as one of the aforementioned Cyathostominae species.

Result Interpretation

The percentage identification of individual species from the analyzed 522 L4 samples were as follows:

• 28.5% of the samples were identified as C. longibursatus
• 25.7% as C. nassatus
• 15.9% as C. ashworthi
• 7.3% as C. goldi
• 1.7% as C. catinatum

Interestingly, it was confirmed that no presence of C. insigne species in any of the L4 samples. Also, when samples from individual horses were compared, no single sample was found to comprise parasites of one species, i.e., each sample contained parasites of at least two species.

Conclusion

Based on these findings, the study surmises that clinical larval cyathostominosis is majorly due to infections from multiple Cyathostomin species concurrently, rather than by a single species.