Immune Response in American Quarter Horses in Relation to Vaccination Time
Reddish, John Mark
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Animal Sciences Undergraduate Research Theses; 2015
Circadian rhythms have been reported to influence immune responses in both humans and animals. Studies in mice have shown that serum antibody concentrations were higher when vaccinated in the evening and a recent study in horses suggests that humoral responses may be increased when antigen exposure occurs in the evening. These studies highlight the potential for time of day to influence immune response to vaccination. Increasing antibody response to vaccination simply by changing the time of day of vaccination may translate into increased vaccine efficacy and improved horse health. In this study, eight Quarter Horse mares (10.5 ± 5.8 yr) were used to evaluate the time of day of vaccination on serum IgA, IgM, IgG, IgGa, IgGb, and IgG(T) concentrations in response to vaccination. Mares were randomly assigned to one of two vaccination groups: AM or PM. All mares received 0.05% BW of a 12% CP pelleted concentrate with mixed grass hay and water ad libitum and were housed in outdoor paddocks with access to shelter at all times. Mares in the AM vaccination group were vaccinated at 0700 hr. Mares in the PM vaccination group were vaccinated at 1900 hr. All mares were vaccinated against Eastern and Western equine encephalomyelitis, equine rhinopneumonitis (EHV-1 and EHV-4), equine influenza (type A2), tetanus and West Nile virus. Blood samples were taken via jugular venipuncture at 1300 hr immediately prior to vaccination (d 0) and on d 7, 14, 21 and 28 post-vaccination. Sera samples were measured for IgG, IgGa, IgGb, IgG(T), IgA and IgM specific antibodies using commercial ELISA kits. Data were analyzed using the PROC MIXED procedure of SAS with d 0 as a covariate and a P value of ≤ 0.05 was considered statistically significant. The immunoglobulins evaluated in this study differed in their response to time of day of vaccination. IgA concentrations increased in response to vaccination and tended to be higher in the PM vaccination group (P = 0.07). There were no differences in IgM, IgGa or IgG(T) concentrations between the mares in the AM and PM vaccination groups. Mares in the PM vaccination group had higher IgGb concentrations on d 7, 14, 21 and 28 d post-vaccination (P < 0.01). However, total IgG concentrations were only increased in the PM vaccination group on d 21 post-vaccination (P < 0.01). Although time of day of vaccination influenced some of the immunoglobulins evaluated in this study, there are additional immune responses that need to be investigated. Further research is needed in this area to determine the optimum time for vaccination.
Academic Major: Animal Sciences
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