We thus reasoned that the genes underlying the observed difference in resistance to tropical theileriosis, might be identified by investigating gene expression differences in m from both breeds. It is possible that relevant polymorphisms might in themselves result in gene expression differences, so initially we targeted likely candidates. However, we detected no differences in expression of the pro-inflammatory cytokines, tumour necrosis factor-α (TNFα), interleukin-1β (IL-1β) or IL-6, in infected m
. As it is more likely that polymorphisms in candidate genes influence the expression of other genes involved in interrelated pathways, we undertook a more global approach. We designed a bovine m
specific cDNA microarray, which contains representatives of 5000 different genes expressed in m
, and investigated the transcriptional responses of m
from both breeds in response to a variety of stimuli, including infection with T. annulata. Our results indicate that there are fundamental differences in gene expression in m
from both breeds in the way they respond to infection, and even in their pre-infection resting state.