Staphylococcus aureus is one of the most important human pathogens responsible for infections in both hospital and community settings. Therapeutic options to combat S. aureus infections are limited due to the high level of antibiotic resistance and lack of an effective vaccine. Thus, there is a significant need for the development of effective therapeutics against this organism. Critical to the pathogenic success of S. aureus is the ability of this bacterium to avoid clearance by the host via targeted killing of neutrophils;innate immune cells integral to the control of Staphylococcal infections. Thus, the long-term goal of this research program is to understand the mechanism employed by S. aureus to deplete these critical phagocytes. Recently, we have described the leukotoxin A/B (LukAB) as a virulence factor that plays an integral role in protecting S. aureus from neutrophil-mediated killing by targeting and eliminating these cells. In addition, we have demonstrated that LukAB contributes to the pathogenesis of community-associated, methicillin-resistant Staphylococcus aureus (CA-MRSA) in a murine model of systemic dissemination. We have found that: LukAB is conserved in S. aureus, contributes to the cytotoxicity of a variety of strains including methicilln-sensitive and methicillin- resistant S. aureus, is responsible for the killing of not only neutrophls, but also monocytes, macrophages and dendritic cells, is the most divergent member of the bi-component pore-forming family of toxins found in S. aureus, and it exhibits unique properties that have not been observed by the other leukotoxins. Based on our findings, we propose a model whereby LukAB selectively binds to phagocytes resulting in toxin oligomerization and pore-formation, which ultimately leads to membrane damage and killing of the target cell. The primary goal of this application is to test this model. To this end, we propose three Specific Aims.
In Aim 1 we plan to elucidate the contribution of candidate cellular factors for LukAB tropism towards phagocytes.
In Aim 2 we seek to define functional regions involved in LukAB-mediated toxicity. Lastly, in Aim 3 we propose to determine the mechanism by which LukAB contributes to S. aureus pathogenesis in vivo. To accomplish these Aims, we propose to employ a multidisciplinary approach that combines molecular biology, genetics, immunology, and biochemistry, together with ex vivo and in vivo infection models. Understanding the molecular details of how LukAB mediates targeting and killing of phagocytes is crucial for the development of novel therapeutic modalities to inhibit this toxin as a new approach to combat S. aureus infections.

Public Health Relevance

This application aims to elucidate the mechanism of action of LukAB, a potent leukotoxin produced by Staphylococcus aureus. Information obtained from the studies proposed in this application will pave the way for developing specific inhibitors to target and block the activity of this toxin, which is likely to provide a new avenue for the treatment of infections caused by this important human pathogen.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01AI099394-02
Application #
8670695
Study Section
Bacterial Pathogenesis Study Section (BACP)
Program Officer
Huntley, Clayton C
Project Start
Project End
Budget Start
Budget End
Support Year
2
Fiscal Year
2014
Total Cost
Indirect Cost
Name
New York University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
City
New York
State
NY
Country
United States
Zip Code
10016
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Maurer, Katie; Reyes-Robles, Tamara; Alonzo 3rd, Francis et al. (2015) Autophagy mediates tolerance to Staphylococcus aureus alpha-toxin. Cell Host Microbe 17:429-40
Spaan, András N; Reyes-Robles, Tamara; Badiou, Cédric et al. (2015) Staphylococcus aureus Targets the Duffy Antigen Receptor for Chemokines (DARC) to Lyse Erythrocytes. Cell Host Microbe 18:363-70
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Maurer, Katie; Torres, Victor J; Cadwell, Ken (2015) Autophagy is a key tolerance mechanism during Staphylococcus aureus infection. Autophagy 11:1184-6

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