Whole blood transcriptomic analysis in BoHV-1 experimentally challenged dairy calves and comparison to a Bovine Respiratory Syncytial Virus (BRSV) challenge

Bovine Herpesvirus 1 (BoHV-1) is a leading cause of Bovine Respiratory Disease (BRD) in young calves, which is responsible for substantial morbidity and mortality. Therefore, the objective of the current study was to elucidate the whole blood mRNA transcriptomic response to an experimental challenge with BoHV-1, in dairy calves. Holstein-Friesian calves were either challenged by intranasal atomisation with BoHV1 virus (6.3 x 10^7/mL x 1.35mL) (n=12) or mock challenged with sterile phosphate buffered saline (n=6). Clinical signs were scored daily until euthanasia at day 6 post-challenge. Total RNA was extracted and sequenced from whole blood (100 bp paired-end). Sequence reads were aligned to the ARS-UCD1.2 bovine reference genome and differential gene expression analysis was performed using EdgeR. An MDS plot displayed an obvious separation between BoHV-1 challenged and control calves based on the gene expression changes in whole blood. There were 488 differentially expressed (DE) genes (p < 0.05, FDR < 0.1, fold change > 2) between the BoHV-1 challenged and control calves. Overall design: Examination of a single tissue type (whole blood) in two different treatment groups, BoHV-1 challenged calves (n=12) and control calves (n=6)