Human bacterial challenge experiments as an alternative
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- Researchers have conducted over 200 safe inoculations of volunteers with pneumococcus to study experimental human carriage. - Studies have found strain differences in carriage rates and that prior carriage protects against future acquisition. The first vaccine study is ongoing. - Future directions include using the model to test vaccines in high-risk populations, discover vaccines by antigen knockout, and study the role of host immunity and adjuvants. It may also provide insights into microbial ecology following vaccine eradication. - Key questions include whether the model can be used in elderly or HIV-infected individuals and whether genetically modified pneumococcus can be used.
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Human bacterial challenge experiments as an alternative
- 1. Stephen Gordon Experimental Human Infection with Pneumococcus November 2013 MRF Annual Conference, London
- 2. Pathogenesis of pneumococcal disease © The Liverpool School of Tropical Medicine 2
- 3. Outline •Previous studies of experimental pneumococcal carriage –Jeff Weiser early work –Our first experiments •How we do our EHPC model –Method, safety issues •Results –Challenge / re-challenge –Humoral response –Cellular response •Where next? –Vaccine testing –Vaccine discovery –Host immunity –Microbial ecology © The Liverpool School of Tropical Medicine 3
- 4. Previous studies of experimental carriage •Jeff Weiser (U Penn, Philadelphia) •JEM 2002 and I&I 2003 Type cfu/naris colonised 23F 5000 0 (4) •Association noted with IgG to 22kD protein in serum 23F 7000 3 (6) •Did not particularly comment on dose dependency 23F 17000 3 (4) •3 washes prior to inoculation 6B 2200039000 6 (8) •Type 23F 6/14 colonised •Type 6B 6/8 colonised •F/up twice weekly and then weekly J Expt Med 2002;195:359-362 and I&I 2003;71:5724-32 © The Liverpool School of Tropical Medicine 4
- 5. Experimental Human Pneumococcal Carriage Early Studies Study number Description Dates n Carriers 1 23F Bronchoscopy Nov 09-Feb 10 9 1 =11% 2 23F No Bronchoscopy Mar 10-Apr 10 6 0 3 6B No Bronchoscopy Oct 2010 7 5= 71% 4 6B Bronchoscopy Jan 11-Mar 11 9 0 5 6B No Bronchoscopy Mar 11-Aug 11 9 2 =22% 6 6B Re-challenge Jun 11-Sep 11 3 0 7 6B No Bronchoscopy-inocula test Sep 2011 5 1=20% 8 23F No Bronchoscopy-inocula test Sep 2011 4 2 =50% 9 Gates EHPC – dose ranging 6B Nov 11-Feb 12 50 21=42% 10 Gates EHPC – dose ranging 23F Feb 12- 60 3=6.0% 11 Gates EHPC - 6B re-challenge Mar 12-May 12 7 0 © The Liverpool School of Tropical Medicine 5
- 6. Outline •Previous studies of experimental pneumococcal carriage –Jeff Weiser early work –Our first experiments •How we do our EHPC model –Method, safety issues •Results –Challenge / re-challenge –Humoral response –Cellular response •Where next? –Vaccine testing –Vaccine discovery –Host immunity –Microbial ecology © The Liverpool School of Tropical Medicine 6
- 7. Method Watch the video © The Liverpool School of Tropical Medicine 7
- 8. Experimental Human Pneumococcal Carriage © The Liverpool School of Tropical Medicine 8
- 9. Outline •Previous studies of experimental pneumococcal carriage –Jeff Weiser early work –Our first experiments •How we do our EHPC model –Method, safety issues •Results –Dose ranging and challenge / re-challenge –Humoral response –Cellular response •Where next? –Vaccine testing –Vaccine discovery –Host immunity –Microbial ecology © The Liverpool School of Tropical Medicine 9
- 10. Dose ranging study 1. Dose ranging studies: 6B and 23F (Gritzfeld, J) in preparation 2. Reproducibility study: 42% carriage Over 200 people inoculated with pneumococcus, no SAE © The Liverpool School of Tropical Medicine 10
- 11. Re-challenge: Carriage protects against acquisition of carriage Subjects PS s1 s2 s3 s4 s5 s6 s7 s8 s9 s10 ++ Proteins Neither + = + = + ++ ++ + ++ + + + Ferreira et al, AJRCCM 2013 © The Liverpool School of Tropical Medicine 11
- 12. Response to carriage- cellular Responses can be compared in non-carriage vs carriage Note IL-17 response following colonisation © The Liverpool School of Tropical Medicine 12
- 13. Macrophages activated with IL17 kill pneumococci p = 0.004 p = 0.013 Percentage change in cfu recovered compared to media Increased uptake compared to vehicle Decreased uptake compared to vehicle 12.5ng/ml 125ng/ml 625ng/ml rhIL-17 dose Overall % increase in uptake © The Liverpool School of Tropical Medicine - 26% ↑ 37% ↑ 13
- 14. Outline •Previous studies of experimental pneumococcal carriage –Jeff Weiser early work –Our first experiments •How we do our EHPC model –Method, safety issues •Results –Challenge / re-challenge –Humoral response –Cellular response •Where next? –Vaccine testing –Vaccine discovery –Host immunity –Microbial ecology © The Liverpool School of Tropical Medicine 14
- 15. Carriage model to test vaccine efficacy (2010) T=0 T=1 T=4 95% Vaccine 29 N=58 Placebo 29 challenge 21 83% 1 1 12 10 *mock challenge 8 challenge 21 *mock challenge 8 *Mock challenge to control for natural acquisition © The Liverpool School of Tropical Medicine 15
- 16. Vaccine (PCV vs Hep A): protection against carriage (2013) © The Liverpool School of Tropical Medicine 16
- 17. Vaccine discovery – Me Vaccine MRC/FAPESP Bilateral Agreement LSTM/ Butantan Institute Learning from acquired immunity (EHPC) how to design better vaccines – Cross-reactive epitopes of PspA Peptide Arrays: linear epitopes Phage display: protective anti-PspA monoclonal antibodies Fragments (conformational epitopes) - IgG CD4+ Th17 Me Vaccine to confer serotypeindependent protection © The Liverpool School of Tropical Medicine 17
- 18. Vaccine discovery - AmiC © The Liverpool School of Tropical Medicine 18
- 19. Host immunity – correlates of protection © The Liverpool School of Tropical Medicine 19
- 20. Microbial ecology - nasotypes © The Liverpool School of Tropical Medicine 20
- 21. Summary of Expt Human Pneumo Carriage project •Safe inoculation of over 200 volunteers –Strain differences in carriage •First vaccine study ongoing –Start with PCV –Plan phase 2a in 2014 •Where next? –Vaccine testing – in risk populations –Vaccine discovery – by antigen knockout –Host immunity – role of adjuvant –Microbial ecology – effect of eradication © The Liverpool School of Tropical Medicine 21
- 22. Thank YOU!! © The Liverpool School of Tropical Medicine 22
- 23. Acknowledgements Home Team • Daniela M. Ferreira, Adam Wright, Sarah Glennie, Toni Banyard • Andrea Collins, Sherouk El Batrawy, Jamie Rylance, Dan Wootton, Ben Morton • Jenna Gritzfeld, Mathieu Bangert, Kondwani Jambo, Shaun Pennington • Angela Wright, Carole Hancock, Dave Shaw, Lorna Roche, Jane Ardrey Collaborators • Eddie Ades (CDC) • Jerry Brown (UCL, London) • Geoff Ginsberg (Duke) • David Goldblatt (ICH, London) • Peter Hermans, Amelieke Cremers, Aldert Zomer (Nijmegen) • Rob Heyderman (Malawi) • Aras Kadioglu (Liverpool) • Keith Klugman, Josh Shak (Emory) • Rick Malley, Mark Lipsitch (Harvard) • Eliane Miyaji, Adriane Moreno (Butantan) Advisors • Jeff Weiser (U Penn), Mark Alderson (PATH) Safety panel • Rob Read, David Lalloo, Brian Faragher ...and our willing volunteers © The Liverpool School of Tropical Medicine Royal Liverpool and Broad Green University Hospitals NHS Trust 23
- 24. Summary of Expt Human Pneumo Carriage project •Safe inoculation of over 200 volunteers –Strain differences in carriage •First vaccine study ongoing –Start with PCV –Plan phase 2a in 2014 •Where next? –Vaccine testing – in risk populations –Vaccine discovery – by antigen knockout –Host immunity – role of adjuvant –Microbial ecology – effect of eradication Key Questions Can we test the model in the elderly? HIV infected? Can we use GMO in the model? Adjuvant? © The Liverpool School of Tropical Medicine 24
- 25. Response to carriage - humoral P=0.01* PLoS Pathog. 2012 Apr;8(4):e1002622. © The Liverpool School of Tropical Medicine 25
- 26. Serum response to challenge by MSD Anti-protein IgG - serum * ** * * ** Pre-challenge samples * * ** * * * *** ** * Ab increased 20/27proteins Post-challenge samples (2 weeks post inoculation) * P≤0.05 comparing pre vs post samples © The Liverpool School of Tropical Medicine 26
- 27. Ab increased 14/27proteins * * * ** ** * * * * ** * Pre-challenge samples Post-challenge samples (2 weeks post inoculation) Ab increased 14/27proteins * * * * * ** © The Liverpool School of Tropical Medicine * * * * * * * P≤0.05 comparing pre vs * post samples 27
- 28. Serum response to challenge by MSD Mock challenge No carriage found Carriage found Mock challenge shows lower post inoculation serum levels; carriage alters response to many proteins Ferreira et al. 2012 Unpub © The Liverpool School of Tropical Medicine 28
- 29. Response to carriage- cellular We can detect Ag-specific responses in BAL but not NW There are no naive mice in human studies of carriage Wright et al. 2012 Unpub. © The Liverpool School of Tropical Medicine 29
- 30. Colonization density- 6B culture Relatively low dose recovery follows inoculation A higher dose does not equal higher colonization density © The Liverpool School of Tropical Medicine 30
- 31. A simple model of defence vs pneumococcal disease © The Liverpool School of Tropical Medicine 31