141. Relationship Between Vaccination Treatment and Cortisol Concentration in Bos Indicus and Bos Indicus-influenced Cattle After Vaccination with a Modified-live Viral Vaccine.

Abstract Combination modified-live vaccines have been determined to negatively affect corpora lutea (CL) integrity and increase serum pro-inflammatory cytokine populations when administered within 45 days of the breeding season. Although cortisol is considered an anti-inflammatory hormone responsible for limiting excessive immune activation during inflammation, the relationship between cortisol and cytokine production in cattle after vaccination is not well understood. The objectives of this study were two-fold: 1) to evaluate whether cortisol concentrations differed by vaccination treatment, and 2) to identify potential inter-relationships of cortisol and pro-inflammatory cytokine populations. Brahman and Brahman F1 heifers (n = 6) and cows (n = 13) were synchronized with a PGF2α injection to regress CL that were present on d-3 relative to d0, when cattle were randomly assigned to a vaccination treatment group: 1) modified live viral (MLV) combination vaccine for both IBR and BVDV antigen (BVDV+IBR; n = 5); 2) MLV containing IBR antigen only (IBR; n = 5); 3) inactivated combination vaccine for both IBR and BVDV antigen (IVV; n = 5); and 4) physiological saline (CON; n = 3). Venipuncture blood samples were processed to obtain sera and plasma on d-3, 0, 3, 5, 11, 18, 21, 28, 38, 48, and 62. Plasma concentrations of IFN-γ, IL-1α, IL-1β, IL-4, IL-6, IL-8, IL-10, IL-17A, IL-36RA, MIP-1α, MIP-1β, IP-10, MCP-1, TNF-α, and VEGF-A concentrations were determined by the MILLIPLEX Bovine Cytokine/Chemokine Magnetic Bead Panel. Serum concentrations of progesterone and cortisol were determined by radioimmunoassay. A d11 progesterone concentration of 1ng/mL or less was indicative of abnormalities in luteal function and estrous cyclicity. Cattle that received the combination (BVDV+IBR) and individual (IBR) MLV vaccine, experienced 20% (1/5) and 60% (3/5) abnormal cycles, respectively. The repeated measures procedure of SAS (v9.4) (with cortisol, cyclicity status, time, treatment, and treatment by time included in the model) tested for differences in concentrations of cytokines and cortisol. Pearson’s correlation analysis was used to identify potential inter-relationships of the analytes. Treatment affected cortisol concentrations (P < 0.0001; BVDV+IBR: 15.7 ± 1.3 ng/mL; CON: 21.2 ± 1.7 ng/mL; IBR: 14.0 ± 1.3 ng/mL; IVV: 22.2 ± 1.3 ng/mL), with a tendency for cortisol to be impacted by time (P = 0.095). Pairwise differences were observed between BVDV+IBR and IVV (P = 0.0005), CON and IBR (P = 0.004), BVDV+IBR and CON (P = 0.01), and IBR and IVV (P < 0.0001) treatments. No differences were observed between BVDV+IBR and IBR or between CON and IVV treatments (P > 0.1). Cortisol was not significantly correlated with any pro-inflammatory cytokine populations (P > 0.1). Overall, vaccination treatments had a significant effect on cortisol concentrations following vaccination, with a negative effect observed in BVDV+IBR. This may provide better understanding into the immune-endocrine response and ovarian dynamics post-vaccination with a MLV vaccine. USDA is an equal opportunity provider and employer.