Hepatitis C virus (HCV) is a major public health concern, and the development of an effective HCV vaccine plays an important role in the effort to prevent new infections. Supramolecular co-assembly and co-presentation of the HCV envelope E1E2 heterodimer complex and core protein presents an attractive vaccine design strategy for achieving effective humoral and cellular immunity. With this objective, the two antigens were non-covalently assembled with an immunostimulant (TLR 7/8 agonist) into virus-mimicking polymer nanocomplexes (VMPNs) using a biodegradable synthetic polyphosphazene delivery vehicle. The resulting assemblies were characterized using dynamic light scattering and asymmetric flow field-flow fractionation methods and directly visualized in their vitrified state by cryogenic electron microscopy. The in vivo superiority of VMPNs over the individual components and an Alum-formulated vaccine manifests in higher neutralizing antibody titers, the promotion of a balanced IgG response, and the induction of a cellular immunity—CD4+ T cell responses to core proteins. The aqueous-based spontaneous co-assembly of antigens and immunopotentiating molecules enabled by a synthetic biodegradable carrier offers a simple and effective pathway to the development of polymer-based supramolecular nanovaccine systems.

Hepatitis C virus (HCV) is a major public health concern, and the development of an effective HCV vaccine plays an important role in an effort to prevent new infections. Supramolecular co-assembly and co-presentation of the HCV envelope E1E2 heterodimer complex and core protein presents an attractive vaccine design strategy for achieving effective humoral and cellular immunity. With this objective, the two antigens were non-covalently assembled with a TLR 7/8 agonist into virus-mimicking polymer nanocomplexes (VMPNs) using biodegradable synthetic polyphosphazene delivery vehicle. The resulting assemblies were characterized using dynamic light scattering and asymmetric flow field flow fractionation methods and directly visualized in their vitrified state by cryogenic electron microscopy. The in vivo superiority of VMPNs over the individual components and an Alum formulated vaccine manifests in higher neutralizing antibody titers, promotion of a balanced IgG response, and induction of CD4+ T cell responses to core proteins. Aqueous-based spontaneous co-assembly of antigens and immunopotentiating molecules enabled by a synthetic biodegradable carrier offers a simple and effective pathway to the development of polymer-based supramolecular vaccine systems.

Background: The quest for well-defined immunoadjuvants remains one of the highest priorities for the successful development of effective vaccines. Combination adjuvants, which are designed to integrate both the ability to activate a variety of immune mechanisms and synergistically improve delivery of vaccine components, are well-positioned to address the unmet needs. The development of preventive vaccine against hepatitis C virus (HCV) – a major public health concern, is a particular instance in which choice of the immunoadjuvant is of utmost importance. Methods: We assembled a lipid A Toll-like receptor 4 (TLR4) agonist BECC438 and TLR7/8 agonist resiquimod (R848) on a polyphosphazene macromolecule (PCPP) to create a nanoscale immunoadjuvant-vaccine delivery system: PCPP-R+BECC438. This aqueous-based system was formulated with HCV sE2 antigen, and the resulting vaccine candidate was evaluated in vivo for the ability to induce immune responses. Results: Co-assembly of adjuvants resulted in a visually clear aqueous system of nanoscale dimensions, monomodal size distribution and entropy driven interactions between components. Intramuscular immunization of mice with HCV sE2 antigen formulated in polyphosphazene-based nano-system induced ten-fold higher IgG and IgG2a titers than the antigen adjuvanted with BECC438 alone. PCPP-R+BECC438 formulated HCV sE2 also produced statistically significant improvements in IgG2a/IgG1 ratio and more robust HCVpp neutralization ID50 titers than control formulations. Conclusions: Polyphosphazene-assembled adjuvant nano-system promotes in vivo immune responses of enhanced quantity and quality of antibodies with increased potency of HCV neutralization.

Background: The quest for well-defined immunoadjuvants remains one of the highest priorities for the successful development of effective vaccines. Combination adjuvants, which are designed to integrate both the ability to activate a variety of immune mechanisms and synergistically improve the delivery of vaccine components, are well-positioned to address the unmet needs. The development of a preventive vaccine against hepatitis C virus (HCV)—a major public health concern—is a particular instance in which the choice of the immunoadjuvant is of utmost importance. Methods: We assembled a lipid A Toll-like receptor 4 (TLR4) agonist BECC438 and TLR7/8 agonist resiquimod (R848) on a polyphosphazene macromolecule (PCPP) to create a nanoscale immunoadjuvant-vaccine delivery system: PCPP-R+BECC438. This aqueous-based system was formulated with the HCV sE2 antigen, and the resulting vaccine candidate was evaluated in vivo for the ability to induce immune responses. Results: Co-assembly of adjuvants resulted in a visually clear aqueous system of nanoscale dimensions, monomodal size distribution, and entropy-driven interactions between components. Intramuscular immunization of mice with HCV sE2 antigen formulated in a polyphosphazene-based nano-system induced ten-fold higher IgG and IgG2a titers than the antigen adjuvanted with BECC438 alone. PCPP-R+BECC438 formulated HCV sE2 also produced statistically significant improvements in IgG2a/IgG1 ratio and more robust HCVpp neutralization ID₅₀ titers than control formulations. Conclusions: Polyphosphazene-assembled adjuvant nano-system promotes in vivo immune responses of enhanced quantity and quality of antibodies with increased potency of HCV neutralization.