Differential gene expression of high and low immune responder Canadian Holstein dairy cows.

Infectious diseases are an important cause of economic loss in the agri-food business. This study investigates indicators of bovine high (HR) and low (LR) immune response and their associated patterns of gene expression. Holstein cows were immunized to induce antibody (AMIR) and cell-mediated (CMIR) immune responses. Based on the results of enzyme-linked immunosorbent assay (ELISA) and delayed-type hypersensitivity (DTH), cows were ranked as HR, LR or average (AR) immune responders. For microarray analysis, phenotypic HR and LR status in both groups was confirmed and total RNA from blood mononuclear cells (BMCs) was obtained. RNA from a pool of AR cows was used as a common reference for hybridization to an in-house cDNAmicroarray. Results of microarray analysis showed transcriptional differences in several immune-related genes between the HR and LR groups. Genes identified as differentially expressed include transcription factors, cytokines, MHC, and TCR-related genes. These results can aid in the establishmentof selection programmes based on broad-based disease resistance, aimed at improving general health in cattle herds.