In this episode, AABP Executive Director Dr. Fred Gingrich discusses recent research with Dr. John Richeson, associate professor of Animal Science at West Texas A&M University. Richeson recently completed a trial which was started due to practicing veterinarians reporting a higher increase in Histophilus somni-associated bovine respiratory disease (BRD) morbidity and mortality after administration of BRSV intranasal vaccine. The immunomodulatory effects of BRSV on H. somni have been previously studied by Gershwin et. al. and the objective of this study by Richeson was to assess the safety, efficacy and BRSV and H. somni nasal shedding in intranasal and parenteral vaccinated high risk beef calves. The study was comprised of three treatment groups, a negative control (no respiratory vaccinations), an intranasal vaccine group, and a positive control (pentavalent parenteral respiratory vaccine). The investigators measured production data, clinical health data, and serology and pathology data for BRSV and H. somni. Richeson walks us through the results of the study as well as the challenges of finding statistical differences for low frequency events. The study results demonstrated that there was no statistical difference in morbidity, mortality, and average daily gain between the treatment groups. They found that the calves who received the intranasal vaccine were statistically twice as likely to have H. somni PCR-positive tests than the positive or negative control groups. These data indicate modified live virus (MLV) vaccination of high-risk calves, either parenterally or intranasally, had little effect on health or growth during the feedlot receiving period. However, intranasal vaccination increased the prevalence of H. somni in the naris. We also discuss comparing the efficacy of antimicrobial metaphylaxis versus on-arrival MLV vaccination to high-risk beef calves. Richeson also discussed the importance of having a negative control group (no vaccination) when performing field trials on vaccine safety and efficacy and his thoughts on the USDA approval process for biologics.
Relevant papers:
1. Veronica I. Munoz, Kendall L. Samuelson, Dexter J. Tomczak, Hannah A. Seiver, Taylor M. Smock, John T. Richeson, Comparative efficacy of metaphylaxis with tulathromycin and pentavalent modified-live virus vaccination in high-risk, newly received feedlot cattle, Applied Animal Science, Volume 36, Issue 6, 2020, Pages 799-807, ISSN 2590-2865, https://doi.org/10.15232/aas.2020-02054.
2. Gershwin, L. (2007). Bovine respiratory syncytial virus infection: Immunopathogenic mechanisms. Animal Health Research Reviews, 8(2), 207-213. doi:10.1017/S1466252307001405