(358e) Engineering Single Shot Vaccine Platform Comprising Liposome Embedded Polyelectrolyte Nanofilms Assembly for Controlled Release of Inactivated Chikungunya Virus

Inactivation of live virus is a commonly used technique to enhance safety in development of vaccines for infectious diseases. Multi-dose requirement for such vaccines often lead to missing or mistimed doses thereby limiting their potency. This in particular can have an adverse effect in controlling an outbreak of vaccine preventable infectious disease such as that of chikungunya (CHIKV) virus in a place without herd immunity. Single shot vaccines capable of releasing the antigen intermittently can potentially be employed to overcome the shortcomings of multi-dose vaccines. A controlled release of antigen here at different time intervals can help in maintaining adequate concentration of antibodies in the system and programmed delayed release can help with increasing or rejuvenating the previous dose. In this study, we are engineering a delivery platform comprising of CHIKV antigen encapsulated lipid nanoparticles (HALNP) embedded in biodegradable polymer films to achieve a sustained spatiotemporal release kinetics of the antigen. The CHIKV virus inactivated using γ-radiations in presence of MDP complex (MDP-iCHIKV) was encapsulated in fluorescently tagged lipid nanoparticles. Several formulations were prepared with particles embedded in polyelectrolyte multilayer (PEM) films so as to obtain an early and a second phase delayed release of the antigen. In-vivo studies were performed where these formulations were injected in mice and the concentration of anti-CHIKV IgG in serum was quantified at different time points. The characterization of liposomes and liposome embedded PEM formulations (HALNP-PEM) was performed using dynamic light scattering to obtain particle size and zeta potential measurements to determine the surface charge. Analysis of encapsulation and released CHIKV antigen concentration was performed using ELISA. Preliminary studies showed that MDP complex protected CHIKV viral envelop proteins while destruction of its genome by γ-radiation and also induced anti-CHIKV IgG response upon injection in mice. In previous studies we have obtained a controlled and linear release profile of therapeutic cargo in HALNP-PEM platform. The encapsulation efficiency of CHIKV antigen in liposomes was nearly 75%. Upon quantifying the fluoresce using plate reader, we obtained about 80% adsorption efficiency of HALNP on PEMs. In-vivo studies with liposome PEM formulations initially showed higher production of anti-CHIKV IgG in early release groups in comparison to delay release groups and then gradual increase in antibody concentration in delay release groups indicating towards intermittent release of antigen due to presence of PEM layers. We are further working towards optimizing the process for multiple controlled release phases and testing long term immune response against CHIKV immunization in mice.