Characterization of T cell responses againstnaturally-induced foot rot in dairy cows.

Abstract

Bovine foot rot, an infectious disease caused by, leads to significant economic losses in the dairy farming. Research on bovine foot rot has primarily focused on the isolation and identification of the pathogen, as well as treatment methods. However, few studies have reported on the host's immunological characteristics following infection. In this study, we employed an eight-color flow cytometry panel to characterize T-cell immune responses in dairy cows after infection by thenaturally-induced foot rot. We found that dairy cows with natural F. necrophorum-induced foot rot exhibited significantly increased percentages of NK cells, NKT cells, CD4CD8(helper) T cells, and CD4CD8(double-positive) T cells compared to healthy cattle, while the proportion of WC1γδ T cells remained unchanged. However, the frequency of CD44expressing cells was significantly elevated across all these T-cell subsets, suggesting their differential activation upon host infection with. Compared with healthy cows, those with natural-induced foot rot showed a significant increase in the percentages of effector memory T cells within NK and CD4CD8T cell populations, and of central memory T cells within CD4CD8and CD4CD8T cells, respectively. Our results, for the first time, revealed a potential role of CD4CD8T cells and NK cells in the defense ofnaturally-induced foot rot in cows.