Acute infection with bovine viral diarrhea virus of low or high virulence leads to depletion and redistribution of WC1+ γδ T cells in lymphoid tissues of beef calves

The objective of this study was to determine the abundance and distribution of γδ T lymphocytes in lymphoid tissue during acute infection with high (HV) or low virulence (LV) non-cytopathic bovine viral diarrhea virus (BVDV) in beef calves. This study was performed using tissue samples from a previous experiment in which thirty beef calves were randomly assigned to 1 of 3 groups: LV [n = 10; animals inoculated intranasally (IN) with LV BVDV-1a (strain SD-1)], HV [n = 10; animals inoculated IN with HV BVDV-2 (strain 1373)], and control (n = 10; animals inoculated with cell culture medium). On day 5 post inoculation, animals were euthanized, and samples from spleen and mesenteric lymph nodes (MLN) were collected to assess the abundance of WC1+ γδ T cells. A higher proportion of calves challenged with BVDV showed signs of apoptosis and cytophagy in MLN and spleen samples compared to the control group. A significantly lower number of γδ T cells was observed in spleen and MLN from calves in HV and LV groups than in the control calves (P < 0.05). In conclusion, acute infection with HV or LV BVDV resulted in depletion of WC1+ γδ T cells in mucosal and systemic lymphoid tissues at five days after challenge in beef calves. This reduction in γδ T cells in the studied lymphoid tissues could be also due to lymphocyte trafficking to other tissues.