Immunological Responses to Tetanus and Influenza Vaccination in Donkeys.

Abstract

BACKGROUND: Donkeys are routinely vaccinated with protocols developed for horses, yet species-specific data on their immune responses are limited. HYPOTHESIS/OBJECTIVES: We hypothesized that donkeys exhibit robust T-cell-mediated immunity and regulatory adaptation after vaccination, comparable to horses. ANIMALS: Thirty-six healthy, seronegative donkeys (34 mares, 2 stallions), aged 0.5-23&#x2009;years (median 8&#x2009;years), from two farms with similar housing and management conditions. METHODS: Prospective study. Animals were selected based on clinical health assessment and confirmed seronegativity for tetanus and equine influenza. All received a multivalent vaccine containing tetanus toxoid and equine influenza antigens. Blood samples were collected at baseline, 1&#x2009;month, and 2&#x2009;months after vaccination. Flow cytometry assessed CD4+, CD8+, and CD4&#x2009;+&#x2009;FoxP3+ T cells (primary outcomes), and monocyte subsets and B lymphocytes (PanB/CD21+) with intracellular IL-10, IL-17, and Ki67 (secondary outcomes). ANOVA with Bonferroni correction (p&#x2009;<&#x2009;0.05) was used for statistical analysis. RESULTS: CD4+ T cells increased from 25.1%&#x2009;&#xb1;&#x2009;1.4% to 37.3%&#x2009;&#xb1;&#x2009;0.7% at month 1, CD8+ from 20.6%&#x2009;&#xb1;&#x2009;1.5% to 32.2%&#x2009;&#xb1;&#x2009;0.9% at month 2 (p&#x2009;<&#x2009;0.001). CD4&#x2009;+&#x2009;FoxP3+ peaked at 11.7%&#x2009;&#xb1;&#x2009;0.6% at month 1 (baseline 6.8%&#x2009;&#xb1;&#x2009;0.8%), then returned to baseline. CD14&#x2009;+&#x2009;MHCII+ and CD14&#x2009;+&#x2009;MHCII- monocytes declined; CD14&#x2009;-&#x2009;MHCII+ increased (p&#x2009;<&#x2009;0.01). PanB/CD21+ cells decreased from 41.5%&#x2009;&#xb1;&#x2009;1.8% to 29.0%&#x2009;&#xb1;&#x2009;1.0%, with significant reductions in IL-10+, IL-17+, and Ki67+ subsets (p&#x2009;<&#x2009;0.001). CONCLUSIONS AND CLINICAL IMPORTANCE: Donkeys exhibit strong T-cell and regulatory immune responses after vaccination, supporting the clinical relevance of applying equine vaccination protocols to donkeys.