Potential prophylactic BCG Prime-booster Gaëlle Noël Kidist Bobosha Subgroup A2 March 16 th, 2011

Enhance and prolong the protective immunity induced by BCG immunization Enhance and prolong the protective immunity induced by BCG immunization Goal Goal

 Live attenuated strain of Mycobacterium bovis  Protects children from severe forms of TB (milliary and meningitis)  Safe and inexpensive  Over 3 billion people got the vaccination globally Limitations o BCG protection wanes through time o Does not prevent against pulmonary disease in adults o Does not protect against re-occurrence or latency o Repeated BCG vaccination failed in enhancing immunity o Risk of disseminated BCG in HIV-infected children o Interferes with Tuberculin-Skin-Test BCG vaccine BCG vaccine

 Safe  Cost effective  Long term protection  Prevention of infection: pre exposure  Prevention of reactivation: post exposure General aims of TB vaccination General aims of TB vaccination

Best strategies are subunit boosters like:  Protein/ fusion protein  Recombinant viral vector  DNA vaccine Prophylactic heterologous prime-boost Prophylactic heterologous prime-boost Boosting BCGNew vaccine

Fusion protein Fusion protein Safe Reproducible Can be freeze-dried Not expensive Not compromised by BCG or environmental mycobacteria exposure … But needs adjuvant …Why not DNA vaccine : delivery system (complex and costy) Live viral vector : previous exposure, expensive

5-10 % of active TB disease % of latent TB infection

 Ag85A (Rv3804c)  Early stage  Rv2660c  Dormant stage  PPE44 (Rv2770c)  Multi-stage Multi-stage fusion protein Multi-stage fusion protein

Ag85A protein (Rv3804c)  Part of the Ag85 complex (Ag85A, Ag85B and Ag85C)  Shared by BCG and Mtb  true booster  Mycolyl transferase A: enzyme involved in the cell wall synthesis  Largely expressed  Secreted and also retained in the cell membrane during early stage of infection  Ag85A/B largely used in new vaccine candicates for their immunogenic capacity

Preclinical data demonstrated:  Large proportion of memory CD4 T cells in the lung recognize Ag85A in young mice (Cooper et al., 1997)  Significant Th1-type cytokine production by splenocytes and significant CTL activity against Ag85A and Ag85B in mice (Lozes et al., 1997) Ag85A protein (Rv3804c)  Ag85A has the potential to boost existing memory immunity in BCG- vaccinated mice - Lung tissue damage dramatically reduced (Brooks et al., 2001)

Rv2660c protein  Starvation protein  Belongs to the Region of Differences RD11  Deleted in BCG Preclinical/Clinical data demonstrated:  Govender et al., 2010: Expression shown to be associated with non-replicating persistence in vitro Persons with latent TB infection preferentially recognize Rv2660 and induced IFN- γ production in a greater proportion compared with patients with TB disease (ex vivo experiments by using patients’ PBMC)  Betts et al., 2002: Expression increased in nutrient-starved cultures (300 fold change) – Effective in the late persistent stage – In the late persistent stage of infection, the effect of adding Rv2660c was particularly pronounced

 Aagaard et al., 2011 Immune response against Rv2660c increases during persistent stage Having Rv2660c in a fusion protein increases protection in late stage Rv2660c protein

 Belongs to the PPE protein family  Secreted by the type VII secretion system encodes by ESAT-6 loci  Romano et al., 2008 PPE44-specific immune responses in acutely, chronically and latently Mtb infected mice PPE44 vaccinated mice showed B and T cell responses with IFN-  and IL-2 release PPE44 seems to be protective PPE44 protein (Rv2770c) (Rv2770c)

IC31 ® adjuvant Intercell product Cationic particles composed of:  Antimicrobial peptide (KLKL 5 KLK)  TLR-9 ligand Oligonucleotide (ODN1a) Combined at a molar ratio of 25:1, respectively  Generates a strong Type 1-dominant humoral and cellular immune response with induction of CTL (Schellack et al., 2006)  Able to slowly release antigen: two month depot effect of IC31 ® may allow single shot protection (Schellack et al., 2006)  Used and seen to be safe  Mouse subcutaneous injection (Schellack et al., 2006)  Guinea pig intramusculary (Skeiky et al., 2010)  Human intramusculary injection (up to 500 nmol KLK + 20 nmol ODN1a) (Dissel et al., 2010)

+ IC31® adjuvant Ag85A Rv2660c PPE44 PFP A multi-stage BCG booster candidate Thank you for your attention…