Browsing by Subject "Johne's"
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Item Genetic analyses of bovine CARD15, a putative disease resistance gene(Texas A&M University, 2004-09-30) Taylor, Kristen HawkinsThrough a binding partner the CARD15 gene activates NF-kB, a molecule with a role in the initiation of the inflammatory immune response. The gene is highly conserved in both structure and function in human and mouse and has recently been implicated as a disease resistance gene in Crohn's disease and Blau Syndrome in human. The gene's relationship to disease and its conservation between species suggests that it may also have a conserved role in bovine disease resistance. To elucidate the potential role of bovine CARD15 in disease resistance, the gene was characterized in cattle. Bovine CARD15 is located 4.2 cR5000 telomeric to ADCY7 on chromosome 18. It spans ~30 kb and is comprised of 12 exons, 11 of which are coding. Bovine CARD15 is expressed in many tissues, but is most abundant in peripheral blood leukocytes. An extensive comparative analysis between the bovine, mouse and human CARD15 genes revealed high levels of inter-species conservation in sequence, genomic structure and protein domains. Conserved putative regulatory motifs were identified in the three species comparison of the 5'UTR, 3'UTR and the intronic sequences flanking exons. Additionally, diverse regulatory motifs were identified in each of the species indicating an evolutionary divergence in the mechanisms of regulation of gene expression. To assess the extent of genetic diversity within bovine CARD15, 41 individuals from nine breeds representing two subspecies were sequenced and screened for polymorphisms. Thirty-six single nucleotide polymorphisms (SNPs) were identified including 26 within the gene transcript. Haplotypes were estimated for each individual and parsimonious SNP sets were identified with which the multi-locus Bos taurus and Bos indicus haplotypes may be reconstructed. There was a significantly higher rate of substitutions within Bos indicus than in Bos taurus. A significantly higher rate of nonsynonymous to synonymous substitutions was found in Bos taurus indicating that positive Darwinian selection is acting on the gene within this subspecies. Association analyses were performed between these SNP loci and haplotypes with Johne's disease. No overwhelming evidence for a simple causal relationship was detected. Assays are provided to screen populations of cattle for variation in the CARD15 gene.Item Three surveillance systems for describing the spatial distribution of Johne's disease seropositivity in Texas cattle(2009-05-15) Pearce, Brielle H.Johne?s disease is a chronic and debilitating disease of cattle caused by infection with Mycobacterium avium subsp. paratuberculosis (Mptb). This disease affects both dairy and beef cattle, though it is more commonly recognized in dairy cattle. Mptb is able to persist in the environment of cattle for extended periods of time; therefore the distribution of the disease depends on the presence of infected animals and environmental conditions. Three surveillance systems were used to describe the spatial distribution of Johne?s disease seropositivity in Texas cattle. These three systems were hypothesized to describe different spatial patterns. These systems involved sampling, 1) herds throughout Texas, 2) market cattle from four markets each month (one each from northern, southern, eastern, and western regions of Texas) and 3) sick animals submitted by veterinarians throughout Texas. Samples were tested for Johne?s disease at the Texas Veterinary Medical Diagnostic Laboratory using serum ELISA. Spatial distributions were estimated by kriging the sample-to-positive control ratios (S/P). Sera were evaluated for Mptb antibodies from 2358 cattle with 1084 animals in system 1, 1200 from system 2 and 74 from system 3. Total number of positive ELISA results was 51, with 25, 19 and 7 positve ELISA results for systems one, two and three, respectively. Results showed an overall prevalence of 2.16%, and prevalence?s of 2.31%, 1.58% and 9.46% for systems one, two and three, respectively. Differences in the spatial distribution of Johne?s disease seropositvity, based on the three surveillance systems, confirmed our hypothesis that estimation of disease distribution is dependant upon the source of surveillance samples.