The Effect of Aging on the Immune Response to Vaccination in the Horse
Vaccination programs are designed to protect an animal from infection, however, depending upon the age and health of the animal vaccination may not stimulate a protective humoral response. It is possible that, as in the human and mouse models, geriatric equines may be less responsive than their younger counterparts to current vaccination protocols. The purpose of this study was to identify an age related diminution in the primary and secondary immune responses of geriatric horses in response to vaccination. Two groups of horses were sampled. The first group consisted of an open herd of 39 privately owned horses, varying in age from 2-27 years of age. The second group consisted of a closed herd of 24 horses ranging in age from 7-over 30 years of age. Each group was vaccinated twice intramuscularly with a commercial equine influenza virus vaccine (Ft Dodge, A/Eq/KY/97). Additionally, one group was vaccinated with keyhole limpet hemocyanin (KLH) in order to study a primary immune response to a novel antigen. The other group was vaccinated with ovalbumin (OVA) for the same purpose. Blood samples were obtained via jugular venipuncture prior to vaccination and monthly thereafter for 5 months. All sera samples were analyzed for antigen-specific antibodies using an ELISA assay. Our results show that all horses responded to primary vaccination with either KLH or OVA, irrespective of age. In contrast, when vaccinated with influenza the middle aged and older horses showed significant differences in the their response between both the herds and the age groups. Thus we were able to demonstrate that age was not a factor in the generation of a primary immune response but was a factor in the generation of a memory immune response. Future research should focus on whether increased frequency of vaccination does in fact increase or maintain vaccine responses and whether antibody responses measured in vitro actually correlate with protection in vivo.
Advisor:Thomas Klei; David Horohov; Dennis French
School:Louisiana State University in Shreveport
School Location:USA - Louisiana
Source Type:Master's Thesis
Keywords:veterinary microbiology and parasitology medical sciences
Date of Publication:06/10/2003