Autophagy, an important host defense pathway, has an essential role in both innate and adaptive immunity. However, many microbes have evolved mechanisms to evade, subvert, or exploit autophagy. Bacterial and viral pathogens can block autophagosome fusion with lysosomes to evade degradation, or utilize nutrients in such vesicles. It has been demonstrated that stimulation of autophagic pathways in macrophages causes mycobacterial phagosomes to mature into phagolysosomes, which can overcome the trafficking block imposed by Mycobacterium tuberculosis. Thus, induction of autophagy suppressed intracellular survival of mycobacteria. We hypothesize that mycobacterial virulence factors mediate autophagy evasion in order to ensure survival within the infected macrophages. The identification and inhibition of such virulence factors will allow us to understand the mechanisms by which autophagy affects the outcome of host-microbe interactions and the immune responses. Through gain-of-function screening of mycobacteria transformed with a cosmid library, we were able to identify two chromosomal regions responsible for manipulating mycobacterial infection- induced autophagy. We propose to study these two genomic regions and evaluate their role on mycobacterial survival and immunity. Increased knowledge of M. tuberculosis infection-induced autophagy may lead to new and promising therapeutics against tuberculosis. Additionally, the pro-autophagic mutants generated in this study may have significant application in the development of effective, safe and persistent TB vaccines.

Public Health Relevance

We propose to study autophagy-regulating genes of Mycobacterium tuberculosis that enhances priming of adaptive immunity. The results of the study will be useful for improving the vaccine efficacy of BCG and developing noble TB vaccine candidates.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
5R21AI095723-02
Application #
8264512
Study Section
Immunity and Host Defense Study Section (IHD)
Program Officer
Parker, Tina M
Project Start
2011-05-15
Project End
2014-04-30
Budget Start
2012-05-01
Budget End
2014-04-30
Support Year
2
Fiscal Year
2012
Total Cost
$196,250
Indirect Cost
$71,250
Name
Duke University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
044387793
City
Durham
State
NC
Country
United States
Zip Code
27705