Altered immune responses to a heterologous protein in ponies with heavy gastrointestinal parasite burdens.
Authors: Edmonds J D, Horohov D W, Chapmat M R, Pourciau S S, Antoku K, Snedden K, Klei T R
Journal: Equine veterinary journal
Summary
# Editorial Summary Gastrointestinal parasites are ubiquitous in equine populations despite the availability of effective anthelmintics, yet their immunological consequences remain poorly characterised in horses and ponies. Researchers compared antibody production, lymphocyte proliferation, and cytokine secretion in response to keyhole limpet haemocyanin (KLH) immunisation across three groups of ponies stratified by parasite burden (high, medium, low), measuring IgG and IgA responses via ELISA alongside in vitro cellular responses. Ponies harbouring high parasite loads demonstrated substantially suppressed humoral immunity—with reduced total immunoglobulin, IgG and IgA titres—alongside impaired lymphoproliferative responses to KLH that failed to recover even with interleukin-2 supplementation; moreover, cells from heavily parasitised animals produced significantly lower IL-4 levels than those from lightly parasitised counterparts. These findings have important implications for vaccination protocols: heavily parasitised ponies mount compromised responses to administered vaccines, suggesting that strategic parasite control may be necessary to optimise immune responses to routine immunisation programmes. Practitioners should consider parasite status when evaluating vaccine efficacy, particularly in young stock or animals with heavy parasite burdens where vaccination response may be substantially diminished.
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Practical Takeaways
- •Parasite control should be optimized before vaccination protocols in horses, as heavy parasite burdens impair vaccine response regardless of parasite burden level
- •Heavily parasitised horses may mount inadequate immune responses to routine vaccinations, potentially requiring post-vaccination serological confirmation or revaccination after parasite clearance
- •Consider fecal egg count assessment prior to vaccination programs; animals with significant parasite burdens may benefit from anthelmintic treatment before immunization to optimize vaccine efficacy
Key Findings
- •Ponies with low parasite burdens showed a trend toward higher KLH-specific total immunoglobulin, IgG(T), and IgA compared to heavily parasitised ponies
- •Heavily and medium parasitised ponies demonstrated significantly reduced lymphoproliferative response to KLH that was not restored by IL-2 addition
- •Cells from heavily parasitised ponies produced significantly lower IL-4 levels compared to lightly parasitised ponies
- •Heavy gastrointestinal parasite burdens uniformly decrease both cellular and humoral immune responses to soluble protein immunization