1. General classes of vaccines An induced mobilization of the immune response for the purpose of therapeutic benefit. Preventative: infectious agents Therapeutic: cancer

2. General classes of vaccines Antibody response CD4+ T cells, B cells MHC class II-dependent Cellular response cytotoxic CD8+ T cells, NK cells MHC class I-dependent

3. Classical success: polio virus vaccine: killed/attenuated virus injected (Salk) oral (Sabin) oral route of infection initial replication in GI tract

4. Paroxysmal success: influenza killed/attenuated virus, protein antibody to viral spike glycoprotein (hemagglutinin, HA) confers protection infects via airway epithelial/systemic replication HA genetic drift subverts antibody

5. Unmitigated failure: HIV killed/attenuated virus recombinant envelope glycoprotein poor protection, cumbersome trials infects via anal/vaginal epithelia replication/residence in immune cells >80 million infected individuals/victims 3.1 million new cases/year in Africa alone

6. Why have HIV vaccines failed? gp120 genetic drift subverts antibody virus is rarely extracellular wrong viral component, wrong delivery? underdesigned? or…overdesigned?

7. Typical antigen formulations peptides bound to carriers (adjuvants) recombinant proteins killed or attenuated virus/bacteria DNA or mRNA encoding protein antigen

8. Typical vaccine delivery vehicles injection in adjuvant (skin, muscle) oral, nasal recombinant or synthetic viral vector transformed microbial vector

9. Engineering rational vaccines understand biology of target understand biology of response bioengineering

11. Production of MHC class I & II-peptide complexes Virus-encoded proteins

12. “Cross presentation” of exogenous antigens on MHC class I: CD8 responses to extracellular agents

13. Dendritic cells initiate antigen- specific immune responses most efficient of all APCs high MHC class I, II & costimulators efficient cross presentation stimulate naïve T cells (CD4, CD8) initiate Ag-specific immune responses All immunization strategies must target DCs

14. Immature: antigen capture Mature: antigen presentation

15. immature DCmature DC Multiple inducers of DC maturation various T cell responses Microbial products / TLR ligands Viral products Inflammatory cytokines Signaling receptors

16. Targeting DCs to elicit immunity: engineering requirements The optimal delivery device… will be targetable to selected DC populations can be coupled to DC maturation agents (microbial, inflammatory, other?) can accomodate any type of antigen permits intracellular targeting (cross-presentation from cytosol favors cytotoxic T cell responses) traceable (does it reach DCs, nodes?) modular (permits efficient, small-scale trials) synthetic, stable, orally available for global use