Antibody responses of ponies to initial and challenge infections of Strongylus vulgaris.

This research focused on studying the antibody responses in ponies against an infection of Strongylus vulgaris, a type of parasite, using a newly developed indirect fluorescent antibody assay (IFA). The findings show antibodies are produced against the parasite in infected ponies, albeit at varied rates, with no antibodies detected in ponies without exposure to the parasite larvae.

Indirect Fluorescent Antibody Assay (IFA)

• The researchers developed an Indirect Fluorescent Antibody (IFA) assay as a method to study the antibody responses in ponies against Strongylus vulgaris, using the third stage larvae (L3) of the parasite as antigens.
• Indirect Fluorescent Antibody (IFA) is a commonly applied laboratory technique in immunology, used for the detection of specific antibodies in a patient’s serum.

Antibody Response

• The study found that a species-specific antibody response to S. vulgaris L3 develops in infected ponies, indicating that the ponies’ immune system recognizes the parasite and reacts accordingly.
• They also discovered that some surface antigens of the L3 larvae are shared by adult worms of the same species.

Measurement of Antibodies Levels

• The research undertook measurement of sequential antibody levels in two groups of ponies, strongyle-naive ponies and immune ponies, following initial and challenge infections using both the newly developed IFA and an already established indirect hemagglutination assay (IHA).
• The study concluded that antibody levels increase faster following initial infections when measured by IFA rather than IHA. Then, upon challenge infections of immune ponies, antibody levels seem to rise when measured with the IFA, but not with IHA.

No Significant Difference Based on Presence of Colic Disease

• The research did not find significant differences in antibody titers between ponies that developed colic, a common digestive disease in horses, following a challenge infection and those that did not.

No Antibodies in Unexposed Ponies

• Unexposed ponies, which did not encounter any larval migrations but underwent a surgical implantation of S. vulgaris adults into the cecum, had no detectable antibodies. This further suggests that exposure to the larvae might be necessary for the immune system to register the presence of these parasites and generate antibodies against them.