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:Mycobacterium avium is one of the prominent disease causing bacteria in humans. It causes lymphadenitis, chronic pulmonary and extrapulmonary and disseminated infections in adults, children and immunocompromised humans. M. avium has ~4,500 predicted gene models, out of which not all are identified at proteomic level. Proteomic database search followed by proteogenomic analysis helps in the correction of gene models, identification of novel exons/genes, variant proteins. As part of this study, we performed proteomic analysis of M. avium cultures by data-dependent acquisition (DDA) and data-independent acquisition (DIA) method followed by proteogenomic analysis of M. avium proteomic data. M. avium culture was subjected to proteomic sample preparation. The resulting peptides were acquired in 120min DDA (12 bRPLC) and DIA method using EASY nLC 1200 liquid chromatogram system coupled to Orbitrap Fusion Tribrid mass spectrometer. The resulting DDA raw files were searched sequentially against the M. avium proteome database, Mycobacterium tuberculosis H37Rv and Ra proteome database (Mtb), M. avium genome six-frame translated proteome and variant proteins database, respectively. The database search result was converted into a spectral library and used for DIA data search for the validation of GSSPs and variant peptides. The database search of M. avium DDA has resulted in the identification of 2,954 M. avium proteins, 128 Mtb proteins, 174 GSSPs (M. avium genome six-frame translated proteome) and 795 SNPs corresponding to 612 proteins (variant proteins database), respectively. The M. avium proteome database search has covered 62.09% of the proteome with the identification of 2,954 proteins out of 4,757 proteins in the database. From the manual categorization of 174 GSSPs, we observed 23 N-terminal extensions, 142 pseudogene coding peptides and one each novel exon and short peptide, respectively.