Reduction of Trypanosoma equiperdum from equine semen by single layer centrifugation.

This study evaluates the efficacy of single layer centrifugation (SLC) in reducing Trypanosoma equiperdum, a parasite that causes a venereal disease in horses, from infected equine semen. The findings suggest that SLC is effective in clearing the parasite but the level of success is dependent on the number of parasites present in the semen.

Objectives of the study

• The primary goal of this research was to determine whether single layer centrifugation (SLC) can be used to purify horse semen infected with Trypanosoma equiperdum, a parasite responsible for the venereal disease called dourine in horses.

Methodology

• Horse semen was artificially infected with different concentrations of the T. equiperdum parasite, ranging from 10 to more than 5 × 10 trypanosomes.
• The existence of the parasite in the semen was validated using a DNA-based method (ITS1 PCR), wet smear examination, and by inoculating the infected semen into mice.
• The standard SLC procedure was performed on all infected semen samples.

Findings

• Before the application of SLC, all samples, excluding negative controls, tested positive for the presence of T. equiperdum.
• After SLC, microscopic examination and DNA detection methods could not find any evidence of the parasite in the semen samples that were initially infected with a lower number of parasites (10 to 100 trypanosomes).
• In semen samples initially infected with higher concentrations of the parasite (from 100 to 5 × 10 trypanosomes), only one out of four samples were found to be parasite-free after SLC.
• All semen samples initially spiked with more than 5 × 10 trypanosomes remained infected even after SLC.
• Animal test results also confirmed the PCR and microscopic findings. Mice injected with SLC-treated semen that had initially lower concentrations of the parasite did not show any signs of infection, similar to those who received negative controls.
• However, in the case of semen initially infected with higher concentrations of the parasite, parasitaemia was observed in some mice after inoculation with SLC-treated semen.

Conclusions

• The study concluded that single layer centrifugation appears to be a viable method for reducing Trypanosoma equiperdum from infected horse semen.
• However, the overall success of this purification process is largely dependent on the original parasite load of the semen sample. The method is less effective at higher levels of infection.