Experimental challenge with bovine herpesvirus 1 in dairy calves: bronchial lymph node mRNA transcriptome response

Bovine Herpesvirus 1 (BoHV1) 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 bronchial lymph node mRNA transcriptomic response to an experimental challenge with BoHV1, 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 bronchial lymph node tissue (150 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 BoHV1 challenged and control calves based on bronchial lymph node gene expression changes. There were 337 differentially expressed (DE) genes (p < 0.05, FDR < 0.1, fold change > 2) between the BoHV1challenged and control calves. Overall design: Examination of a single tissue type (bronchial lymph node) in two different treatment groups, BoHV1 challenged calves (n=12) and control calves (n=6)