Classical vaccines incorporating live or attenuated microorganisms possess several disadvantages and cannot be applied against cancer and some pathogens. Modern vaccines utilizing minimal immunogenic subunits (peptides) derived from a particular pathogen are able to overcome these obstacles but need a specific delivery system for their efficacy.
Nanotechnology has opened a new window into these delivery methodologies. Particles-based subunit vaccine formulations have been proven to be very effective in inducing cellular and humoral immune responses. Polymer-based materials are widely used for production of nano/microparticles and more recently have been also used for vaccine delivery.
We have designed new delivery system based on the polyacrylate polymer with self-assembled properties and shown that humoral immune responses induced with help of this polymer were dependent on the produced particle size. The strong immune responses were observed even after single subcutaneous immunization. The polymer-peptide conjugates were also used for the design of therapeutic vaccine against cervical cancer. We have also used other polymers for peptide-based vaccine delivery. Significantly, liposomes (bearing lipopeptide vaccine) that were coated with alginate and trimethyl chitosan (TMC) stimulated strong systemic and mucosal immune responses even when administered orally. No sign of common oral immune tolerance was detected. As expected, uncoated lipopeptide vaccine candidate was not effective when administered orally, most likely due to its degradation in the gastrointestinal tract. TMC/dextran/lipopeptide nanoparticles were also effective at inducing immune responses against low doses of antigen when administered intranasally.
Our findings suggested that polymer-based delivery systems are very promising for the design of peptide-based vaccines and not only removes the use of incompletely defined and ordinarily toxic immune adjuvants, but also significantly improve efficacy of peptide based vaccines.