Project description:Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia and a major factor in the porcine respiratory disease complex. A clear understanding of the mechanisms of pathogenesis does not exist although it is clear that M. hyopneumoniae adheres to porcine ciliated epithelium by action of a protein called P97. Previous studies have shown variation in the gene encoding the P97cilium adhesin within different strains of M. hyopneumoniae, but the extent of genetic variation among field strains across the genome is not known. Since M. hyopneumoniae is a worldwide problem, it is reasonable to expect that a wide range of genetic variability may exist given all of the different breed and housing conditions. This variation may impact the overall virulence of a single strain. Using microarray technology, this study examined potential variation of fourteen field strains in comparison to strain 232 on which the array was based. Genomic DNA was obtained, amplified with TempliPhi™, and labeled indirectly with Alexa dyes. Post genomic hybridization, the arrays were scanned and data analyzed using a linear statistical model. Results indicate that genetic variation could be detected in all fourteen field strains but across different loci, suggesting that variation occurs throughout the genome. Fifty-nine percent of the variable loci were hypothetical genes. Twenty-two percent of the lipoprotein genes showed variation in at least one field strain. A permutation test identified a location in M. hyopneumoniae genome where spatial clustering of variability between the field strains and strain 232 exists. Keywords: CGH, Mycoplasma Hyopneumoniae
Project description:Mycoplasma hyopneumoniae is the causative agent of porcine enzootic pneumonia and a major factor in the porcine respiratory disease complex. A clear understanding of the mechanisms of pathogenesis does not exist although it is clear that M. hyopneumoniae adheres to porcine ciliated epithelium by action of a protein called P97. Previous studies have shown variation in the gene encoding the P97cilium adhesin within different strains of M. hyopneumoniae, but the extent of genetic variation among field strains across the genome is not known. Since M. hyopneumoniae is a worldwide problem, it is reasonable to expect that a wide range of genetic variability may exist given all of the different breed and housing conditions. This variation may impact the overall virulence of a single strain. Using microarray technology, this study examined potential variation of fourteen field strains in comparison to strain 232 on which the array was based. Genomic DNA was obtained, amplified with TempliPhiâ¢, and labeled indirectly with Alexa dyes. Post genomic hybridization, the arrays were scanned and data analyzed using a linear statistical model. Results indicate that genetic variation could be detected in all fourteen field strains but across different loci, suggesting that variation occurs throughout the genome. Fifty-nine percent of the variable loci were hypothetical genes. Twenty-two percent of the lipoprotein genes showed variation in at least one field strain. A permutation test identified a location in M. hyopneumoniae genome where spatial clustering of variability between the field strains and strain 232 exists. TempliPhi⢠amplified DNA samples from field isolates were compared to control strain 232 using a two-color experimental microarray design. Independent samples from one isolate labeled with one dye were paired with control samples labeled with the alternate dye; the samples were mixed and hybridized to the microarray. For nine of the fourteen isolates (95MP1501, 95MP1502, 95MP1503, 95MP1504, 95MP1508, 95MP1509, 97MP0001, 00MP1301, and 05MP2301), four independent field isolate DNA samples were paired with four independent DNA samples from control 232. In two of the four arrays, the control sample was labeled with Alexa 555 dye and compared to the field isolate sample labeled with Alexa 647 dye (Molecular Probes, Inc., Eugene, Ore.). The dye assignment to control and treated samples was reversed for the other two arrays (dye swap). The arrays were hybridized under identical conditions as described below. This procedure was repeated for isolates 95MP1510 for a total of four arrays, where the control sample was labeled with Alexa 647 dye in three of the arrays and Alexa 555 dye for the fourth array. For isolates 95MP1505, 95MP1506 and 95MP1507, a total of five arrays each, including two dye swaps, were done; and for isolate 00MP1502, a total of six arrays were done with the control labeled with Alexa 555 dye for four of the arrays and Alexa 647 for the other two arrays.
Project description:Mycoplasma hyopneumoniae, the causative agent of swine enzootic pneumonia, colonizes the cilia of swine lungs, causing ciliostasis and cell death. Mycoplasma hyopneumoniae is a component of the porcine respiratory disease complex (PRDC) and is especially problematic for the finishing swine industry, causing the loss of hundreds of millions of dollars in farm revenues worldwide. For successful infection, M. hyopneumoniae must effectively resist oxidative stresses due to the release of oxidative compounds from neutrophils and macrophages during the host’s immune response. However, the mechanism M. hyopneumoniae uses to avert the host response is still unclear. To gain a better understanding of the transcriptional responses of M. hyopneumoniae under oxidative stress, cultures were grown to early exponential phase and exposed to 0.5% percent hydrogen peroxide for 15 minutes. RNA samples from these cultures were collected and compared to RNA samples from control cultures using two-color PCR-based M. hyopneumoniae microarrays. This study revealed significant down-regulation of important glycolytic pathway genes and gene transcription proteins, as well as a protein known to activate oxidative stressor cascades in neutrophils. This study has also contained significantly differentially expressed genes common to other environmental stress responses, and merits further study of universal stress response genes of M. hyopneumoniae. Keywords: Mycoplasma hyopneumoniae, RNA microarray
Project description:Mycoplasma hyopneumoniae pathogenic strains, like 7448, are the causative agents of porcine enzootic pneumonia. Non-pathogenic strains, like M. hyopneumoniae J, does not cause disease, although shares the entire repertoire of known virulence-related genes with M. hyopneumoniae 7448. In this context, the differential expression of ortholog genes is likely responsible, at least in part, for differences in pathogenicity or virulence level between these strains. Moreover, in the porcine lung, M. hyopneumoniae faces a hostile environment, with both oxidative and heat stresses. The performed comparative proteomics analyses provided evidence of differential stress responses between a pathogenic and a non-pathogenic M. hyopneumoniae strain, involving tens of proteins, including some known virulence factors. The results suggest that stress conditions trigger the expression of potential virulence factors in the pathogenic M. hyopneumoniae 7448, but not in the non-pathogenic M. hyopneumoniae J.