Expression analysis of Mycobacterium avium subsp. paratuberculosis K-10 within macrophage cell line

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. Bacterial total RNA was purified from Mycobacterium avium subsp. paratuberculosis that was infected into J774A.1 cells grown with or without interferon-gamma activation at 2 or 24 h post-infection. RNA from bacteria incubated with PRMI-1640 medium for 2 h, which was the infection conditon, is used as control condition. Each condition has two biological replicates. Each hybridization represents expression levels of all 4,350 annotated genes with 20 60-mer oligonucleotides and with three technical replicates.