Identification of virulence determinants of Mycobacterium avium that impact on the ability to resist host killing mechanisms

• Published in: Journal of medical microbiology Vol. 59; no. 1; pp. 8 - 16
• Main Authors: Li, Yong-jun, Danelishvili, Lia, Wagner, Dirk, Petrofsky, Mary, Bermudez, Luiz E
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01.01.2010; Society for General Microbiology
• Subjects: Animals; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Cells, Cultured; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Bacterial; Genetic Complementation Test; Humans; Hydrogen-Ion Concentration; Infectious diseases; Macrophages - immunology; Medical sciences; Mice; Mice, Inbred C57BL; Microbiology; Miscellaneous; Mutation; Mycobacterium avium - drug effects; Mycobacterium avium - pathogenicity; Nitric Oxide - pharmacology; Pathogenicity and Virulence; Phenotype; Tuberculosis - immunology; Tuberculosis - microbiology; Vacuoles - chemistry; Virulence; Mycobacteriales; Virulence; Mycobacteriaceae; Mycobacterium avium; Bacteria; Actinomycetes; Identification; Mechanism
• ISSN: 0022-2615; 1473-5644
• DOI: 10.1099/jmm.0.012864-0

1 Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA 2 Department of Internal Medicine II – Infectious Diseases, University of Freiburg, 79106 Freiburg, Germany 3 Kuzell Institute, California Pacific Medical Center Research Institute, San Francisco, CA, USA 4 Department of Microbiology, College of Science, Oregon State University, Corvallis, OR, USA Correspondence Luiz E. Bermudez luiz.bermudez{at}oregonstate.edu Received May 14, 2009 Accepted September 7, 2009 Mycobacterium avium is an opportunistic pathogen associated with pulmonary disease in non-AIDS patients and disseminated infection in patients with AIDS. The chief route of infection is by colonization and invasion of the mucosa of the gastrointestinal tract, but infection through the respiratory route also occurs. After crossing the mucosa, M. avium infects and replicates within tissue macrophages. To identify M. avium genes required for survival in vivo , a library of signature-tagged transposon mutants was constructed and screened for clones attenuated in mice. Thirty-two clones were found to be attenuated for their virulence, from which eleven were sequenced and tested further. All the mutants studied grew similarly in vitro to the wild-type MAC104. Ten mutants were tested individually in mice, confirming the attenuated phenotype. MAV_2450, a polyketide synthase homologue to Mycobacterium tuberculosis pks12, was identified. STM5 and STM10 genes (encoding two hypothetical proteins MAV_4292 and MAV_4012) were associated with susceptibility to oxidative products. Mutants MAV_2450, MAV_4292, MAV_0385 and MAV_4264 live in macrophage vacuoles with acidic pH (below 6.9). Mutants MAV_4292, MAV_0385 and MAV_4264 were susceptible to nitric oxide in vitro . The study of individual mutants can potentially lead to new knowledge about M. avium pathogenic mechanisms. Tables of growth and susceptibility data for the wild-type and mutant isolates are available as supplementary data with the online version of this paper.