Bioinformatics based design of thermostable virus-like particles-based vaccine for foot-and-mouth disease serotype A and in-vivo evaluation in guinea pigs

Background Foot-and-mouth disease (FMD) is a contagious disease affecting cloven footed animals. Existing vaccines although effective, has limitations of short immunity, needs cold chain maintenance, high biosafety levels facilities for production and inability to differentiate infected from vaccinated animals. Virus-like particles (VLPs) provide an alternative strategy and the structural integrity of VLPs at moderate temperatures or acidic pH plays major role as they destabilize the capsid and exhibits poor immunogenicity when used as vaccine. Stabilized capsids are developed using bioinformatics approach to predict amino acids in the structural proteins of the FMD virus, which may provide thermostability and can withstand live virus challenge. Methods Baculovirus expression system offer an attractive method for producing VLPs of foot-and-mouth disease virus, which mimics the native virus and elicits protective immune response. In-silico bioinformatics structural analysis was harnessed to predict thermostable amino acids on the VP2 and VP3 proteins of FMDV serotype A/IND/40/2000 by employing molecular modelling. Consequent mutations were introduced into the VP2 and VP3 proteins, F62Y and H142D, respectively, resulting in the formation of a double mutant (AM-3) and VLPs expressed in Tn5 cells. The AM-3 VLPs were tested in thermostability test in-vitro for different temperature and time points and also tested by in-vivo in guinea pigs for vaccine efficacy. Results The demonstration of capsids of FMDV in the transmission electron micrograph confirmed the expression of AM-3 VLPs. Thermostability studies revealed AM-3 had significantly low degradation (62.5%) on 15 days post storage at 37°C amongst all VLPs and validated by in-vivo studies. Finally, the VLPs conferred 90% protection in guinea pigs and could serve as a thermostable candidate vaccine. Conclusion The thermostable AM-3 VLPs produced based on bioinformatics without compromising the structural integrity, could confer protective immunity in preclinical studies and which can serve as a potential thermostable candidate vaccine for FMDV serotype A/IND/40/2000 for controlling FMD in ruminants.