(2is) Engineering Single Shot Vaccine Platform Comprising Liposome Embedded Polyelectrolyte Nanofilms Assembly for Controlled Release of Inactivated Chikungunya Virus

Immunization through inactivated virus enhances the safety profile of

the vaccine and is one of the most efficient technique to protect against

infectious diseases. However, inactivated vaccines require multiple

rounds of vaccinations that often lead to missing or mistimed doses

thereby limiting their potency. This multidose requirement further limits

mass immunization during the outbreak of an infectious disease such

as chikungunya virus (CHIKV) 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 and provide herd immunity in shorter period of time. A

sustained release of antigen can help in maintaining high concentration

of antibodies in the system and programmed delayed release can

induce strong booster effect. In this study, we engineered a single shot

vaccine delivery platform comprising liposomes (LNP) embedded

polyelectrolyte multilayer (PEM) lattice to provide controlled

spatiotemporal release of CHIKV antigen and thus induce long term

immunity. The CHIKV virus inactivated using γ-radiations in presence of

MDP complex (MDP-iCHIKV) was injected in mice and tested for

production of antibodies. The MDP-iCHIKV were then encapsulated in

LNP followed by embedment in PEM films so as to obtain a

programmed release of antigen at different time points. We performed

the characterization of LNP and LNP-PEM assembly using dynamic

light scattering method to determine the size and zeta potential

measurements to determine the surface charge. Further confocal

imaging and scanning electron microscopy was conducted to analyze

the structure properties of the LNP-PEM assembly. Analysis of

encapsulation and released CHIKV antigen concentration was

performed using ELISA. In-vivo studies were performed by injecting the

LNP-PEM assembly in mice followed by quantification of anti-CHIKV

IgG in serum at different time points. The 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. Significant changes in size, charge and structural

properties were observed in the process of LNP embedment into PEM

thus confirming the intended design of the vaccine plaform . We

obtained about 75% encapsulation efficiency of CHIKV antigen in LNP

and nearly 80% adhesion efficiency of LNP on PEM. In-vivo studies

showed patterned increase and decrease in production of anti-CHIKV

IgG indicating towards intermittent release of antigen from the LNPPEM

assembly. We are further working on optimizing the design of this

single-shot vaccine platform to achieve a programmed release of

antigen at multiple stages. We believe that this design for single shot

vaccine platform would not only eliminate the need for multiple booster

shots for inactivated vaccines but can also be potentially employed for

long term immunization against a variety of pathogens.