Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb) infections, claims the lives of 2- 3 million people annually. The importance of the development of more efficient drugs and vaccines is reinforced by: the emergence of multi-drug resistant and extreme-drug resistant Mtb strains and secondly, the deadly synergism between the HIV/AIDS epidemic and TB due to reactivation of persisting bacteria.This proposal seeks to test the hypothesis that the capacity of Mtb to inhibit infection-induced apoptosis of macrophages is a major pathway of the bacteria to avoid the host?s innate and adaptive immune response. Furthermore it proposes that the discovery of mycobacterial genes involved in the inhibition of host cell apoptosis will lead to new drug targets for resolving persistent bacterial infections and to new improved attenuated vaccine strains. Presently, the capacity of mycobacteria to inhibit macrophage apoptosis has been linked to bacterial virulence based only on correlative data due to the lack of defined bacterial mutants.
The AIM 1 of the proposal targets to fill that gap in our knowledge by identifying several mycobacterial genes important for apoptosis inhibition using a unique ?gain-of-function? genetic screen. The success of this approach has been proven by the identification of one anti-apoptotic gene of Mtb, nuoG, but at least two additional genes remain to be identified.
AIM 2 proposes to characterize the molecular mechanisms by which nuoG is able to suppress host cell apoptosis. Finally, in AIM 3 the bacterial mutants are used to address the importance of apoptosis inhibition for the bacterial escape from the host?s innate and acquired immune response in immunodeficient and immunocompetent mice, respectively. In addition, the identified anti-apoptotic gene will be deleted in the currently used TB vaccine strain (BCG) and the effect of the mutation on the vaccine potential will be tested in the mouse model of TB. Altogether, the successful completion of the proposed studies would lead to the identification of new TB drug targets and may result in an improved TB vaccine strain.

Public Health Relevance

One third of the world?s population is infected with Mycobacterium tuberculosis and each year 30 million people get sick and 2-3 million people die of the resulting disease, tuberculosis. The proposal aims to identify new targets within the bacteria for the development of more efficient drugs and vaccines.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI072584-03
Application #
7761229
Study Section
Host Interactions with Bacterial Pathogens Study Section (HIBP)
Program Officer
Jacobs, Gail G
Project Start
2008-02-01
Project End
2013-01-31
Budget Start
2010-02-01
Budget End
2011-01-31
Support Year
3
Fiscal Year
2010
Total Cost
$334,125
Indirect Cost
Name
University of Maryland College Park
Department
Anatomy/Cell Biology
Type
Schools of Earth Sciences/Natur
DUNS #
790934285
City
College Park
State
MD
Country
United States
Zip Code
20742
Shah, Swati; Cannon, Joe R; Fenselau, Catherine et al. (2015) A Duplicated ESAT-6 Region of ESX-5 Is Involved in Protein Export and Virulence of Mycobacteria. Infect Immun 83:4349-61
Srinivasan, Lalitha; Ahlbrand, Sarah; Briken, Volker (2014) Interaction of Mycobacterium tuberculosis with host cell death pathways. Cold Spring Harb Perspect Med 4:
Shah, Swati; Bohsali, Amro; Ahlbrand, Sarah E et al. (2013) Cutting edge: Mycobacterium tuberculosis but not nonvirulent mycobacteria inhibits IFN-? and AIM2 inflammasome-dependent IL-1? production via its ESX-1 secretion system. J Immunol 191:3514-8
Briken, Volker; Ahlbrand, Sarah E; Shah, Swati (2013) Mycobacterium tuberculosis and the host cell inflammasome: a complex relationship. Front Cell Infect Microbiol 3:62
Briken, Volker (2013) Mycobacterium tuberculosis genes involved in regulation of host cell death. Adv Exp Med Biol 783:93-102
Abdalla, Hana; Srinivasan, Lalitha; Shah, Swati et al. (2012) Mycobacterium tuberculosis infection of dendritic cells leads to partially caspase-1/11-independent IL-1? and IL-18 secretion but not to pyroptosis. PLoS One 7:e40722
Briken, Volker (2012) ""With a little help from my friends"": efferocytosis as an antimicrobial mechanism. Cell Host Microbe 12:261-3
Blomgran, Robert; Desvignes, Ludovic; Briken, Volker et al. (2012) Mycobacterium tuberculosis inhibits neutrophil apoptosis, leading to delayed activation of naive CD4 T cells. Cell Host Microbe 11:81-90
Briken, Volker; Mosser, David M (2011) Editorial: switching on arginase in M2 macrophages. J Leukoc Biol 90:839-41
Bohsali, Amro; Abdalla, Hana; Velmurugan, Kamalakannan et al. (2010) The non-pathogenic mycobacteria M. smegmatis and M. fortuitum induce rapid host cell apoptosis via a caspase-3 and TNF dependent pathway. BMC Microbiol 10:237

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