Gene expression in the medulla following oral infection of cattle with bovine spongiform encephalopathy

The identification of variations in gene expression in response to bovine spongiform encephalopathy (BSE) may help to elucidate the mechanisms of neuropathology and prion replication and discover biomarkers for disease. In this study, genes that are differentially expressed in the caudal medulla tissues of animals infected with different doses of PrP at 12 and 45 mo post infection were compared using array containing 24,000 oligonucleotide probes. Data analysis identified 966 differentially expressed (DE) genes between control and infected animals. Genes identified in at least two of four experiments (control versus 1-g infected animals at 12 and 45-mo; control versus 100-g infected animals at 12 and 45 mo) were considered to be the genes that may be associated with BSE disease. From the 176 DE genes associated with BSE, 84 had functions described in the Gene Ontology (GO) database. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of 14 genes revealed that prion infection may cause dysfunction of several different networks, including extracellular matrix (ECM), cell adhesion, neuroactive ligand-receptor interaction, complement and coagulation cascades, MAPK signaling, neurodegenerative disorder, SNARE interactions in vesicular transport, and the transforming growth factor (TGF) beta signaling pathways. The identification of DE genes will contribute to a better understanding of the molecular mechanisms of neuropathology in bovine species. Additional studies on larger number of animals are in progress in our laboratory to investigate the roles of these DE genes in pathogenesis of BSE

Microarray analysis of differentially expressed genes from peyer's patches of cattle orally challenged with bovine spongiform encephalopathy

The most likely route of entry of infection following oral exposure to transmissible spongiform encephalopathies (TSE) is via the immunologically active Peyer's patches (PP). These secondary lymphoid organs appear to be the potential route for prion neuroinvasion. However, the molecular mechanisms involved in the uptake of the infectious prion agent and progression of disease remain still unclear. This investigation examined the changes in gene expression in PP following oral exposure of cattle to bovine spongiform encephalopathy (BSE) agents. The gene expression patterns in PP from cows 12 mo after BSE challenge were compared with controls using a microarray platform containing 24,000 oligonucleotides representing 16,846 unique gene loci and 5943 Expressed Sequence Tag (EST) from bovine genome. Between the challanged and control animals, 90 genes and 16 EST were identified as significantly differentially, expressed (2.0-fold change): 36 were upregulated and 70 were downregulated. Of these genes, five were found to be related to immune function. Major histocompatibility complex (MHC) class II, MHC class II DQ alpha, L-RAP, and two hypothetical proteins. Differentially expressed genes related to cellular and metabolic processes including development and maturation of cells in the PP were also identified. In this context, the potential impacts of these gene expression changes in PP on BSE development are discussed