Differential gene expression in cattle challenged with single pathogens of the bovine respiratory disease complex

Abstract Text:

Bovine respiratory disease complex (BRDC) is an important infectious cause of mortality and morbidity in cattle. BRDC develops when stressed cattle are infected with one of several viruses followed by one or more bacterial pathogens. To evaluate the host response to each of these pathogens we measured global transcript abundance using RNA sequence analysis, comparing infected steers with normal controls after single pathogen infections.  At maximum clinical signs, steers were euthanized for necropsy and collection of lung, bronchial, nasopharyngeal, and retropharyngeal lymph nodes, and pharyngeal tonsils for RNA sequencing. Viral agents used for the challenge were: bovine respiratory syncytial virus (BRSV), infectious bovine rhinotracheitis (IBR), and bovine viral diarrhea virus (BVDV).  Bacteria used to challenge included: Mannheimnia hemolytica, Pasteurella multocida, and Mycoplasma bovis.   Differential expression of genes coding for non-specific defense innate immunity and the acute phase response was found among all pathogen infections.  These included pattern recognition receptors, mucins, and host defense peptides; more specific immune response genes were differentially expressed in individual pathogen infections. Adaptive immune system pathways for both T and B cells were activated in BRSV infection. In general viral infections elicited a greater number of differentially expressed genes than bacterial pathogens. Tissues were compared and found to contain both differentially expressed genes shared among all tissues examined and specific to tissue type. Overall data obtained will have important implications for design of better therapeutic modalities; and will help further elucidate the complex pathogenesis of BRDC.

Keywords: BRDC, infection, RNA