Transcriptome profiling of peripheral blood mononuclear cells from highly susceptible adult cattle infected with a virulent strain of Babesia bovis
Bovine babesiosis is a tick-borne disease that poses a significant economic threat to cattle industries in tropical and subtropical areas, and Babesia bovis is the most virulent causative agent of bovine babesiosis. This apicomplexan parasite infects erythrocytes of cattle causing severe hemolytic disease, and animals that survive acute infections become persistently infected for life. Young cattle (< 6 months of age) are resistant to infection while adult cattle (>1 year of age) are highly susceptible and succumb to acute infection; however, the immunological mechanisms associated with the age-resistance remain unclear. Protective host immunity involves peripheral blood mononuclear cells (PBMCs) including natural killer (NK) and T cells, and activated macrophages that act to control the pathogen. In this study, we examined the transcriptional signatures of PBMCs from adult cattle (>1.5 years old) experimentally infected with the B. bovis virulent strain S74-T3Bo. Transcriptional signatures evident during the acute phase of babesiosis were categorized into immune-related and non-immune genes. We identified both upregulated and downregulated genes, with fold changes ranging from 2 to 263-fold. We discuss our findings in the context of immune responses to acute disease as a mechanism for adult host survival, with a focus on the molecular functions and biological processes involved in the response to B. bovis infection. In this RNA-Seq analysis, we identified genes related to the immune system, including cytokines and chemokines, complement, cell signaling pathways and surface molecules that may play a role in the recognition of pathogen-associated molecular patterns. In addition, non-immune genes potentially involved in cell proliferation, cell migration, development, energy production, protein-protein interactions, molecular transport, and flagella assembly were also identified. Overall design: In this study, we examined the transcriptional signatures of peripheral blood mononuclear cells (PBMCs) from adult cattle (>1.5 years old) experimentally infected with the B. bovis virulent strain S74-T3Bo.