Kinetics of Immune Cells and Neutralizing Antibody Titres Against Viral Pathogens of Bovine Respiratory Disease
Date
2024-01-19
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Abstract
Bovine Respiratory Disease (BRD) arises from complex interactions between viral and bacterial pathogens, environmental stressors, and host factors. BRD significantly impact feedlots due to its high prevalence, economic impact, and animal welfare concerns. Therefore, implementing an effective preventive management strategy, such as preconditioning (PC) aims to reduce the incidence and health impact of BRD in feedlots compared to conventional auction-derived practice. To measure and compare the health impact and effectiveness of this strategy, we evaluated the proportion of immune cells (cell-mediated and humoral) and neutralising antibodies (NAb) using the flow cytometry technique and virus neutralisation assay, respectively. Peripheral blood mononuclear cells (n=8) and serum (n=20) samples from preconditioned (PC) and auction-derived (AD) cattle were evaluated at three different time points in the feedlot (day 0, day 20, and day 40) to determine the proportion of immune cells (CD21+ B cells, CD4+ Th cells, CD3+ CTLs, and WC1+ γδ T cells) and to determine the NAb titres (against BHV 1, BVDV, BRSV and BPIV 3). We observed a high B cell response, and high and persistent NAb titres against BRD viral pathogens in PC cattle during the first 40 days in the feedlot compared to the AD group. Furthermore, most of the lymphocytes among the CD3+ T cells were WC1+ γδ expressing cells, with a smaller proportion of CD4+ expressing T-helper and CD8+ expressing cytotoxic T-lymphocytes, however, the CD4+ Th cells showed major fluctuations in their proportions within the PBMCs. In conclusion, the result provided us with a strong understanding of the immune response in PC calves, particularly the humoral immunity, and specifically the number of NAbs induced following preconditioning. This will help with the prediction of BRD in young calves during their first 40 days in a feedlot, and to evaluate the efficacy of vaccination strategies in preconditioning programs.
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Keywords
Bovine Respiratory Disease, Preconditioning, Feedlot, Humoral Immune Response, Cell-Mediated Immune Response, Neutralising Antibodies
Citation
Choden, T. (2024). Kinetics of immune cells and neutralizing antibody titres against viral pathogens of Bovine Respiratory Disease (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.