|MCGILL, JODI - Kansas State University|
Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2016
Publication Date: 5/31/2016
Publication URL: http://handle.nal.usda.gov/10113/63139
Citation: McGill, J.L., Sacco, R.E. 2016. Gamma delta T cells and the immune response to respiratory syncytial virus infection. Veterinary Immunology and Immunopathology. doi: 10.1016/j.vetimm.2016.02.012.
Interpretive Summary: In this invited review, we have discussed the role of a specific population of white blood cells in calves in the response to a respiratory virus. This particular population of white blood cells is found at high levels in the very young calf (up to 60% in some studies). As the calves get older, the percentages of these cells decrease, suggesting they may play an important role in the immune response of the young calf. There have been relatively few studies that have looked at the role of these white blood cells in the immune response to a respiratory virus. The virus studied is an important cause of respiratory illness in young calves under one year of age. It is also important part of a group of infections that are a leading cause of illness and death in feedlot cattle. We review the current literature, including our own publications in this field, and where appropriate, compare to publications in laboratory animals and humans.
Technical Abstract: 'd T cells are a subset of nonconventional T cells that play a critical role in bridging the innate and adaptive arms of the immune system. 'd T cells are particularly abundant in ruminant species and may constitute of up 60% of the circulating lymphocyte pool in young cattle. The frequency of circulating 'd T cells is highest in neonatal calves and declines as the animal ages, suggesting these cells may be particularly important in the immune system of the very young. Bovine respiratory syncytial virus (BRSV) is a significant cause of respiratory infection in calves, and is most severe in animals under one year of age. BRSV is also a significant factor in the development of bovine respiratory disease complex (BRDC), the leading cause of morbidity and mortality in feedlot cattle. Human respiratory syncytial virus (RSV) is closely related to BRSV and a leading cause of lower respiratory tract infection in infants and children worldwide. BRSV infection in calves shares striking similarities with RSV infection in human infants. To date, there have been few studies defining the role of 'd T cells in the immune response to BRSV or RSV infection in animals or humans, respectively. However, emerging evidence suggests that 'd T cells may play a critical role in the early recognition of infection and in shaping the development of the adaptive immune response through inflammatory chemokine and cytokine production. Further, while it is clear that 'd T cells accumulate in the lungs during BRSV and RSV infection, their role in protection vs. immunopathology remains unclear. This review will summarize what is currently known about the role of 'd T cells in the immune response to BRSV and BRDC in cattle, and where appropriate, draw parallels to the role of 'd T cells in the human response to RSV infection.