Development of a glycoconjugate vaccine to combat disease caused by Haemophilus influenzae type A

Transcription

1 Development of a glycoconjugate vaccine to combat disease caused by Haemophilus influenzae type A Dr. Andrew Cox National Research Council Canada, ttawa, Canada

2 Haemophilus influenzae a (Hia) invasive disease Invasive Hia disease is an emerging infectious disease that affects Aboriginal populations in the post-hib. conjugate vaccine era. In collaboration with federal, state and provincial partners, PHAC & CDC have been tracking invasive Hia disease over the last several years. (Emerg. Inf. Dis (28) 14, 48-55)

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4 Haemophilus influenzae capsular polysaccharide structures a: ->4- -D-Glc-> 4-ribitol-5-P 4 -> b: ->3- -D-Rib-> 5-ribitol-1-P 4 -> c: ->4- -D-GlcNAc-1->3- -D-Gal-1-> 3 Ac (9%) d: ->4- -D-GlcNAc-1->3- -D-ManNAcA-1-> 6 Ala/Ser/Thr (2:2:1) (8%) e: ->3- -D-GlcNAc-1->4- -D-ManNAcA-1-> f: ->3- -D-GalNAc-1->4- -D-GalNAc-1->P 4 ->

5 Hia CPS purification HD Ribol-4/5 Hia fermenter growth has been optimised to afford ~ 4mg / L of CPS. This is an industrially acceptable scale Glc-1 Ribol-5 Glc-2 Glc-5 H Glc H H H H H Serotype a: ->4- -D-Glc-> 4-ribitol-5-P 4 -> P - n 1 H-NMR spectrum

6 Hia conjugation strategy Sizing (sonication), activation (periodate oxidation), conjugation (reductive amination) Hia polymer xidised Hia polymer Glc H H H H H H P - n NaI 4 H Glc P - H H Protein N a C N B H 3 n H Glc H H H H H P - k H Glc H H P NH-Protein - l H Glc H H H H H P - m

7 SDS-PAGE analysis of Hia-CRM and Hia-ProD conjugates 7.5% mini TGX precast, Coomassie ) Ladder 2) CRM 3) CRM-Hia conj. 9 4) CRM-Hia conj. 1 (for rabbits) 5) Protein D 6) ProtD-Hia (for rabbits)

8 Immunisation of mice and rabbits with glycoconjugates Mice (ip) and rabbits (sc) received a prime and two boost schedule of the glycoconjugates with adjuvant. Final bleed sera was taken and screened against the polysaccharide antigen and then whole cells to determine the immunogenicity of the conjugate Sera is then used in a functional in vitro assay to determine if the derived sera is capable of facilitating bactericidal killing of the Haemophilus influenzae serotype a strains

9 Hia conjugate sera ELISA vs. BSA-Hia RCAV 1-3 H. influenzae A-CRM; Dose 35ug CH, 14ug CRM RPAV 1-3 H. influenzae A-ProD; Dose 35ug CH, 14ug ProD Pre-immune sera 6min D 45nm :5 1:1 1:2 1:4 1:8 1:16 1:32 1:64 1:128 1:256 1:512 1:124 RCAV1 RCAV2 RCAV3 6min D 45nm :5 1:1 1:2 1:4 1:8 1:16 1:32 1:64 1:128 1:256 1:512 1:124 RPAV1 RPAV2 RPAV3

10 Hia conjugate sera ELISA vs. BSA-Hia RCAV 1-3 H. influenzae A-CRM; Dose 35ug CH, 14ug CRM RPAV 1-3 H. influenzae A-ProD; Dose 35ug CH, 14ug ProD Post-immune D7 sera 6min D 45nm :5 1:1 1:2 1:4 1:8 1:16 1:32 1:64 1:128 1:256 1:512 1:124 RCAV1 RCAV2 RCAV3 6min D 45nm :5 1:1 1:2 1:4 1:8 1:16 1:32 1:64 1:128 1:256 1:512 1:124 RPAV1 RPAV2 RPAV3

11 Hia conjugate sera ELISA vs Hia strain min D 45nm :5 1:1 1:2 1:4 1:8 1:16 1:32 1:64 1:128 1:256 1:512 1:124 RCAV1 RCAV2 RCAV3 Pre 6min D 45nm :5 1:1 1:2 1:4 1:8 1:16 1:32 1:64 1:128 1:256 1:512 1:124 RPAV1 RPAV2 RPAV3 Pre

12 Hia conjugate sera bactericidal activity vs Hia strain 6753 SBA Killing % SBA Killing % vs 6753 vs RCAV Pre RCAV 1 RCAV 2 RCAV RPAV Pre RPAV 1 RPAV 2 RPAV :2 1:1 1:5 1:25 1:125 1:625 1:2 1:1 1:5 1:25 1:125 1:625

13 Summary of SBA data for serotype Hia conjugate sera Table 1. Bactericidal titers 1 of pre- and post-immunisation rabbit sera from CRM and Protein D Hia capsular polysaccharide conjugates against H. influenzae type a strains. Baby rabbit complement was used at the maximum concentration that did not kill. Sera / Strain Pre / Post HiA-CRM conjugate RCAV1 Pre nk 2 nk nk nk nk nk nk nk nk nk nk nk nk nk Post 25K 125K 625K 625K 25K 25K 1K 25K 125K 25K 25K 125K 125K 125K RCAV 2 Pre nk nk nk nk nk nk nk nk nk nk nk nk nk nk Post 25K 125K 625K 625K 25K 25K 1K 25K 125K 25K 25K 125K 125K 125K RCAV 3 Pre nk nk nk nk nk nk nk nk nk nk nk nk nk nk HiA-prot. D conjugate Post 125K 25K 125K 125K 25K 5K 5K 5K 125K 25K 25K 25K 125K 125K RPAV1 Pre nk nk nk nk nk nk nk nk nk nk nk nk nk nk Post 1K 1K 5K 5K 1K 2 1K 2 1K 1K 1K 5K 1K 5K RPAV2 Pre nk nk nk nk nk nk nk nk nk nk nk nk nk nk Post 1K 1K 25K 5K 1K 2 1K 2 2 1K 1K 5K 5K 5K RPAV3 Pre nk nk nk nk nk nk nk nk nk nk nk nk nk nk Post 5K 5K 25K 25K 5K 5K 1K 5K 25K 25K 25K 25K 25K 125K 1 Bactericidal titers expressed as the reciprocal of the serum dilution yielding >= 5% killing when compared to the corresponding pre-immune sera; 2 nk, no killing.

14 Hia glycoconjugate vaccine conclusions Hia capsular polysaccharide can be isolated and purified from flask and fermenter growth. Growth conditions have been optimised to yield ~ 4mg/L Capsular polysaccharide structure has been confirmed by NMR. Glycoconjugate vaccines have been prepared using several carrier proteins including CRM and protein D via a reductive amination strategy. Mice and rabbits have been immunised with conjugates and good serum titers were produced that have facilitated bactericidal killing of ALL Hia strains in our collection thus illustrating the pre-clinical proof of concept.

15 Key next steps Further engagement with First Nations, Inuit and Métis communities is essential and is ongoing Clinical lot production and clinical trial capabilities are in place to produce vaccine and carry out Phase 1 and 2 funding? Need for clinical trial sites at some stage in indigenous communities Interest from Canadian and Alaskan Indigenous health communities Early discussions with the regulator are necessary to address concerns over whether or not Phase 3 is feasible -- correlates of protection? A business plan/policy paper needs to demonstrate value of an Hia vaccine: Consider guaranteed procurement of doses to attract industry Demonstrate subsequent economic burden of disease (e.g. lifetime cost of one seriously deformed child after MenB infection: $3 4.5M GBP) Government responsibility to all its citizens and globally

16 Federal Initiative on Vaccine Research, Innovation and Development Seeks to:- target, strengthen and accelerate the development of vaccines and vaccine technologies needed to meet evolving public health and agricultural sector productivity needs. By focusing on :- the nature and challenges of vaccine research, innovation and development in Canada. the availability and adequacy of existing mechanisms, to support the development and commercialization of vaccines and vaccine technologies in Canada. opportunities to enhance the strategic focus and coordination of federal programs in support of Canada s vaccine research, development and manufacturing sectors. vaccine candidates for which there is not sufficient market pull vaccines that have technological challenges which can be de-risked and thereby would become attractive to industry for further development

17 Acknowledgements Andrew Cox Chantelle Cairns Dean Williams Frank St. Michael Wei Zou Luis Baretto Perry Fleming Rhonda Kuo Lee Luke Masson Jim Richards Lakshmi Krishnan Raymond Tsang Shalini Desai Monique St. Laurent John Spika Guillaume Poliquin Rhonda Kropp Cindi Corbett Michelle Shuel Matt Gilmour Andree Anne Boisvert Marina Ulanova Eli Nix Karen Miernyk David Scheifele Ben Tan