Molecular pathogenesis and Prevention. of Staphylococcus aureus Infections. Prof. Olaf Schneewind

Transcription

1 Molecular Pathogenesis and Prevention of Staphylococcus aureus Infections Louis Block Professor and Chair, Department of Microbiology University of Chicago 920 East 58 th Street, Chicago, IL Staphylococcus aureus About 4% of hospital admission in the United States acquire S. aureus infections Leading cause of bloodstream, lower respiratory tract, skin & soft tissue infections Many staphylococcal hospital infections caused by methicillin-resistant (MRSA) strains Many community acquired (CA) infections caused by CA-MRSA Annual US mortality exceeds that of HIV/AIDS or any other infectious disease FDA licensed vaccine not available 2 The envelope of Grampositive bacteria J.L. Strominger, J.M. Ghuysen and D.J. Tipper (1965) 3 1

2 Protein A O. Schneewind et al.; Navarre et al. 4 Sortase A - anchoring proteins in the envelope of Gram-positive bacteria S. Mazmanian et al. 5 S. aureus sortase A mutants S. Mazmanian et al. 6 2

3 Sortase A cleavage of LPXTG peptides Fluorescent intensity (Arbitrary unit) Ton-That et al. 7 Sortase A catalyzed transpeptidation Ton-That et al. 8 LPXTG peptide bound to sortase A Zhong et al. 9 3

4 Deposition of protein A in the staphylococcal envelope A. DeDent et al. hibition (minutes) Time following trypsin inh 10 Protein A on the staphylococcal surface A. DeDent et al. 11 Signal peptides of staphylococcal surface proteins A. DeDent et al. 12 4

5 DIC Distribution of surface proteins in the cell wall envelope +YSIRK Alexa647- IgG Merge DIC -YSIRK Alexa647- IgG Merge spa - spa - αclfa αsasf spa - /clfa - spa - /sasf - spa - spa - αsdrd A. DeDent et al. spa - /sdrd - αsasa spa - /sasa - 13 Signal peptides address surface proteins to specific envelope locations A. DeDent et al. 14 Protein traffic to the cell wall envelope of Staphylococcus aureus A. DeDent et al. 15 5

6 Fate of Staphylococcus aureus Newman injected into the bloodstream of mice Staphylococcus aureus Newman is inoculated directly into the mice s blood stream We use about 10 7 cfu Immediately after injection the organism resides in the blood and distributed into the peripheral tissues 16 Staphylococcal abscess formation in the kidney of mice 17 Architecture of day 2 lesions Day

7 Architecture of day 5 lesions Day 5 19 Scanning electron microscopy of staphylococci in host tissues 20 Sortase mutants cannot form abscesses 21 7

8 Sortase A is essential for staphylococcal persistence in host tissues 22 Sortase mutants in renal tissue 23 Surface abscesses 24 8

9 Surface proteins involved in abscess formation and persistent infection 25 Hypothesis A protective antigen can be thought of as a genetic and biochemical entity within microbes, here Staphylococcus aureus, that is both required for disease pathogenesis and, when offered to the immune system of experimental animals in isolated form, able to generate protective immunity against this disease What are the protective antigens of staphylococci? 26 Surface proteins and protective immunity Y. Stranger-Jones et al. 27 9

10 Vaccine protection against staphylococcal abscess formation with IsdAB/SdrDE Y. Stranger-Jones et al. 28 Staphylococcal abscesses enable persistence 29 Heme-iron transport in staphylococci S. Mazmanian et al. E. Skaar et al. Fe 30 10

11 Sortase B and the IsdC anchor structure L. Marraffini et al. 31 Protein topologies in the cell wall of staphylococci L. Marraffini et al. SrtA SrtB 32 Staphylococcal envelope associated proteins Envelope associated protein AA residues Ligand Association Emp 341 Fibronectin, fibrinogen SDS extractable Ebh Fibronectin Membrane protein Efb 165 Complement factor C3b Secreted, weak association EbpS 486 Elastin Membrane protein Eap/Map 689 Plasma proteins SDS extractable 33 11

12 Eap and Emp wild-type emp emp (pemp) 34 Staphylocccal load and persistence when lacking envelope associated proteins 35 Eap mutants form abscesses 36 12

13 Emp mutants cannot form abscesses 37 Distribution of Eap and Emp during staphylococcal abscess formation 38 Eap and Emp vaccines 39 13

14 Vaccine protection against lethal Staphylococcus aureus challenge Y. Stranger-Jones et al. H. Kim et al. 40 Staphylococcus aureus and human lung infections Community-acquired staphylococcal pneumonia, particularly frequent in children, young adolescents and elderly patients Hospital-acquired staphylococcal pneumonia of individuals with ventilator-assistedassisted respiration Hospital-acquired staphylococcal pneumonia occurs frequently in patients with cardiothoracic surgery High mortality Human pneumonia is more often caused by methicillinresistant (MRSA) than by methicillin-sensitive S. aureus (MSSA) strains 41 Staphylococcus aureus pneumonia in mice Percent mortality Newman stra- strb- spa- icaa J. Bubeck-Wardenburg Percent mortality Newman agra- hla

15 Murine pneumonia model J. Bubeck-Wardenburg 43 Mechanisms of alpha-hemolysin (Hla) assembly and function M. Montoya and E. Gouaux (2003) BBA 1609: Alpha-hemolysin is an essential virulence factor for S. aureus pneumonia J. Bubeck-Wardenburg 45 15

16 Active immunization with the Hla protects against staphylococcal pneumonia J. Bubeck-Wardenburg 46 Passive immunization with Hla antibodies protects against staphylococcal pneumonia J. Bubeck-Wardenburg 47 University of Chicago Ted Bae Alice Cheng Andrea DeDent Matt Frankel Hwan Kim Gwen Liu Sarkis Mazmanian Molly McAdow William Navarre Eric Skaar Vilasack Thammavongsa Hung Ton-That Yukiko Stranger-Jones Luciano Marraffini Juliane Bubeck Wardenburg Acknowledgements Support National Institute of Allergy & Infectious Diseases research awards RO1-AI and RO1-AI52474 (Region V) Great Lakes Regional Center of Excellence for Biodefense and Emerging Infectious Diseases (U54-AI057153) Novartis Vaccines & Diagnostics Collaborations Dominique Missiakas (University of Chicago) Andrzej Joachimiak (Argonne National Laboratory) Shantam Narayana (University of Alabama, Birmingham) Fabio Bagnoli, Guido Grandi and Rino Rappuoli (Novartis Vaccines & Diagnostics) 48 16

17 49 17