Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2014

Mycobacterial pathogenesis: comparative genomics between human and animal associated subspecies of the Mycobacterium avium complex (#440)

Verlaine Timms 1 , Karl Hassan 2 , Hazel M Mitchell 1 , Brett A Neilan 1
  1. School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW, Australia
  2. Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
This study explores specific pathogenic factors associated with the genus Mycobacteria, a group of bacteria collectively responsible for more than 3 million deaths annually. A rare human isolate of Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis), a known pathogen of livestock, was compared genomically to other human mycobacterial pathogens. This human strain of M. paratuberculosis was recently isolated and belongs to the M. avium complex (MAC), a group that can infect both humans and animals. The mycobactin cluster, PE/PPE genes and mammalian cell entry (mce) operons between MAC subspecies that infect animals and those that infect humans, including the new human isolate, were compared. In addition, M. tuberculosis was included in these analyses given its predominant role as a human pathogen. This genome comparison showed the PPE/PE profile of the new isolate to be largely the same as other M. paratuberculosis isolates, except that it had one PPE and one PE_PGRS protein that were only present in human MAC strains and M. tuberculosis. PPE/PE proteins that were unique to this isolate, M. avium subsp. hominissuis and a caprine M. paratuberculosis isolate, were also identified. In addition, the mycobactin cluster differed between human and animal isolates and a unique mce operon flanked by two mycobactin genes, mbtA and mbtJ, was identified in all available M. paratuberculosis genomes. The mce operon and the M. paratuberculosis-specific PPE protein may be involved in iron scavenging pathways in this subspecies. This study highlights key factors of mycobacterial pathogenesis in humans and forms the basis for future functional studies.