Project description:A comparative genomic approach was used to identify large sequence polymorphisms among Mycobacterium avium isolates obtained from a variety of host species. DNA microarrays were used as a platform for comparing mycobacteria field isolates with the sequenced bovine isolate Mycobacterium avium subsp. paratuberculosis (Map) K10. ORFs were classified as present or divergent based on the relative fluorescent intensities of the experimental samples compared to Map K10 DNA. Map isolates cultured from cattle, bison, sheep, goat, avian, and human sources were hybridized to the Map microarray. Three large deletions were observed in the genomes of four Map isolates obtained from sheep and four clusters of ORFs homologous to sequences in the Mycobacterium avium subsp. avium (Maa) 104 genome were identified as being present in these isolates. One of these clusters encodes glycopeptidolipid biosynthesis enzymes. One of the Map sheep isolates had a genome profile similar to a group of Mycobacterium avium subsp. silvaticum (Mas) isolates which included four independent laboratory stocks of the organism traditionally identified as Maa strain 18. Genome diversity in Map appears to be mostly restricted to large sequence polymorphisms that are often associated with mobile genetic elements. Keywords: Comparative genomic hybridization
Project description:Once entering the cell, M. avium subsp.paratuberculosis is known to survive harsh microenvironments, especially those inside activated macrophages. To improve our understanding of M. avium subsp.paratuberculosis pathogenesis, we examined the phagosome maturation associated with transcriptional responses of M. avium subsp.paratuberculosis during macrophage infection. Monitoring cellular markers, only live M. avium subsp.paratuberculosis bacilli were able to prevent phagosome maturation and reduce its acidification. On the transcriptional level, over 300 of M. avium subsp.paratuberculosis genes were significantly, differentially regulated in both naïve and IFN-γ-activated macrophages. These genes include the sigma factor H (sigH) that was shown to be important during persistent infection in M. tuberculosis.
Project description:We focused on how Mycobacterium avium subsp. paratuberculosis influences the subsequent host response to investigate the host immunopathology accompanying the host anti-mycobacterial immune response during Mycobacterium avium subsp. paratuberculosis infection in spleen of mice.
Project description:We focused on how Mycobacterium avium subsp. paratuberculosis influences the subsequent host response to investigate the host immunopathology accompanying the host anti-mycobacterial immune response during Mycobacterium avium subsp. paratuberculosis infection in spleen of mice. We analyzed altered transcription in the spleen of mice at 3, 6, and 12 weeks following Mycobacterium avium subsp. paratuberculosis infection.
Project description:Deep sequencing was implemented to study the transcriptional landscape of Mycobacterium avium TMC724. High-resolution transcriptome analysis identified the transcription start points for 652 genes. One third of these coincided with the start codons and therefore belong to leaderless transcripts, whereas the rest of the transcripts had 5' UTRs with the mean length of 83 nt. In addition, the 5' UTRs of 6 genes contained SAM-IV and Ykok types of riboswitches. 87 antisense RNAs and 9 intergenic small RNAs were mapped. Four of the revealed intergenic small RNAs, including igMAV_1034-1035 expressed at a very high level, have no homologs in M. tuberculosis, whilst M. avium lacks several intergenic sRNAs present in M. tuberculosis. Among those, MTS479 and MTS1338 are of special interest due to their possible implication in pathogenesis. Elucidation of differences in the repertoire of intergenic sRNAs between the two mycobacterial species may improve our understanding of mycobacterial diseases pathogenesis. Transcriptional profile of Mycobacterium avium TMC724, grown at 37M-BM-0C in Dubos broth until mid-logarithmic growth phase
