Comparative Expression Profiling In The Three Defined Forms Of Ovine Paratuberculosis

The response of the macrophage is thought to pivotal to the outcome of the bacterial infection by Mycobacterium avium subsp. paratuberculosis (Map), tuberculosis and leprosy (1). Using oligonucleotide based microarray, we aim to characterise the transcriptome signature of alveolar macrophages, lymph node and ileum, derived from sheep showing the three forms of Map infection. This technology will test two hypotheses:1) There are intrinsic differences in the way macrophages respond to Map infection in the three forms of the disease (asymptomatic, paucibacillary and multibacillary).2) Differences in the immuno-inflammatory gene expression in gut associated lesions are directly related to the different pathological forms of the disease.To address these hypotheses, we have designed a Ruminant Immuno-inflammatory Gene Universal Array (RIGUA), which will measure the expression of 434 different ruminant immuno-inflammatory genes in the three forms of the disease. In developing this microarray we have produced a first generation chip; the Ruminant Immuno-inflammatory Gene Reference Array (RIGRA). This is being used for initial validation and to examine intrinsic variations of gene expression within and between individual sheep. This paper will describe the development of the microarray and our initial validation experiments.