Immune responses of Bos indicus versus Bos taurus cattle towards Bluetongue virus or Schmallenberg virus differ significantly.

Cattle are the mammalian species with most global biomass, encompass the two subspecies Bos taurus and Bos indicus, which are phenotypically distinguishable and have distinct genetic backgrounds. We used fresh primary bovine blood cells to characterize and dissect host-pathogen interactions, hypothesizing that Bos taurus and Bos indicus cattle exhibit different immune responses towards vector-borne diseases (VBDs) impacting the clinical disease outcome. We tested Schmallenberg virus (SBV) and Bluetongue virus (BTV), examples of vector-borne pathogens responsible for recent European disease outbreaks, driven by increased vector activity linked to rising temperatures. Bos taurus cattle showed a moderate ex vivo response towards SBV compared to BTV (i.e., qualitative and magnitude changes in activation/maturation state of immune cells and cytokine secretions), which indicates a fine-tuning of the immune response depending on vector-borne virus. The most striking finding was the differential immune response towards BTV: broad and over-exuberant in Bos taurus (i.e., antiviral, cellular and humoral), mainly antiviral in Bos indicus. Moreover, fever-like temperature, a classical clinical sign of disease, reduced the capacity of most immune cell subsets to respond to the pathogens tested. Overall, our findings reinforce other studies that suggest different susceptibilities of the Bos indicus versus Bos taurus towards major pathogens.