The Effect of Time of Day of Vaccination on Interleukin 10 Gene Expression in Horses

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Vaccinations are used in animal industries to reduce severity and duration of future disease by presenting a weak or dead version of a virus to the immune system. Previous studies show that immune response can be affected by the concentration of chemical messengers (cytokines) in the blood. Cytokine production has been shown to change throughout the day, so it has been suggested that the immune system would be better able to respond more strongly or quickly at a certain time of day. If this were true, it would be possible to improve vaccine efficacy and improve animal health by simply changing the time of vaccination. The purpose of this study was to determine if time of day of vaccination affects the gene expression of the cytokine Interleukin 10 (IL-10) in horses, and therefore impacts the efficacy of a vaccine. Eight Quarter Horse mares (10.5 ± 5.8 yrs) and 6 miniature horse geldings (7 ± 2.6 yrs) were randomly assigned into an AM or PM vaccination group. Horses in the AM and PM vaccination groups were vaccinated intramuscularly against Eastern and Western encephalomyelitis, rhinopneumonitis (EHV-1 and EHV-4), influenza (type A2), and West Nile Virus at 0700 and 1900 h, respectively. Blood samples were collected via jugular venipuncture on days 0, 7, 14, and 21 for analysis. RNA was extracted from the samples and underwent reverse transcription and quantified using real-time PCR. It was found that IL-10 gene expression was higher in all horses vaccinated in the AM group compared to the PM group, and that IL-10 expression in mares was greater on d 7, 14, and 21 than on d 0, and higher in the miniature horses on d 7 and 21 than on d 0. This study suggests that AM vaccinations elicit a greater immune response.


Agriculture/Ecological/Environmental Science (The Ohio State University Denman Undergraduate Research Forum)


Interleukin 10, vaccination, equine