PH-Responsive Polymer-Antigen Vaccine Bioconjugates


Protein-based vaccines play an important role in controlling infectious disease but their full clinical impact has been limited by their inability to generate a coordinated cellular CD4+ and CD8+ immune response. Vaccines that better deliver antigens to the cytosolic MHC1 display system could in principle provide a better coordinated response. Here, controlled radical polymerization was employed to prepare a diblock copolymer containing an endosomal releasing segment based on poly(propylacrylic acid) (poly(PAA)) and a hydrophilic segment containing thiol-reactive disulfide moieties for antigen conjugation. Propylacrylic acid (PAA) was polymerized in the presence of a trithiocarbonate based RAFT chain transfer agent (CTA). The resultant poly(PAA) was then employed as a macroCTA in the copolymerization of pyridyl disulfide methacrylamide (PDSMA) (thiol-reactive monomer) and N,N-dimethylacrylamide (DMA) as a hydrophilic comonomer. Copolymer compositions and molecular weights were determined via 1H NMR spectroscopy and size exclusion chromatography. Native polyacrylamide gel electrophoresis (PAGE) showed a complete disappearance of the bands corresponding to free thiolated ovalbumin after conjugation to the polymer at pyridyl disulfide to thiol ratios as low as 2.5. The ability of the poly[(PAA)-b-(DMA)co(PDSMA)]-ovalbumin conjugates to activate CTLs was evaluated in vivo, tumor protection using the EG7 tumor protection model. Tumors were visible in the PBS and free ovalbumin immunized mice by day 7 but were not visible in the polyPAA-ovalbumin conjugate immunized mice until day 18. The mice immunized with the polyPAA-ovalbumin conjugate had a survival rate at day 21 of 100% versus 20% for PBS and 40% for ovalbumin immunized mice.


Materials Science and Engineering

Keywords and Phrases

Bioconjugates; Chain transfer agents; Co-monomer; Controlled radical polymerization; Copolymer compositions; Cytosolic; Diblock copolymer; Display system; H NMR spectroscopy; Hydrophilic segments; Immune response; In-vivo; Infectious disease; Methacrylamides; N ,n-dimethylacrylamide; Ovalbumins; PH-responsive; Poly(N-acetylaniline); Polyacrylamide gel electrophoresis; Pyridyl disulfide; Segment-based; Survival rate; Trithiocarbonate; Tumor protection, Acrylic monomers; Antigens; Block copolymers; Copolymerization; Display devices; Electrophoresis; Free radical polymerization; Gel permeation chromatography; Hydrophilicity; Immunization; Mammals; Nuclear magnetic resonance spectroscopy; Size exclusion chromatography; Tumors; Vaccines, Polymers

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Article - Journal

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© 2011 Royal Society of Chemistry, All rights reserved.

Publication Date

01 Jul 2011