Comparative efficacy of virus like particle (VLP) vaccine of foot-and-mouth-disease virus (FMDV) type O adjuvanted with poly I:C or CpG in guinea pigs

• CpG adjuvanted FMDV-VLP vaccine induced significant cell mediated immune response in Guinea pigs.
• FMDV-VLP vaccine with CpG showed 75% protection compared to 66% and 62% in ISA206 and poly IC based VLP vaccine.
• CpG was more efficacious than ISA206 and Poly-IC adjuvants in providing protection against FMDV challenge in guinea pigs.
• Protective efficacy of FMDV-VLP vaccine was enhanced by CpG adjuvant.

Foot-and-mouth disease (FMD) is one of the most contagious and economically important diseases of cloven-hoofed livestock. Currently used inactivated FMD vaccines have short lived immunity besides risk of handling live virus. We studied recombinant FMD virus like particles (VLPs) encoded by FMDV type O/IND/R2/75 polyprotein genes expressed in Sf9 cells and adjuvanted with CpG or Poly I:C in inducing protective immune response in guinea pigs. Guinea pigs immunized with VLP + CpG vaccine had shown markedly higher cell mediated immunity (CMI) in comparison to the conventional vaccine group as evident from higher levels of IgG2 than IgG1. Although the humoral response was less in VLP + CpG compared to conventional vaccine, the lymphocyte stimulation index was more in VLP + CpG compared to conventional and VLP + Poly I:C vaccine groups. Finally the challenge experiments on 28 and 56 dpv had shown 75% protection in VLP + CpG immunized guinea pigs primary and boosted animals, while 50% and 62% protection in VLP + Poly I:C in primary and boosted animals, respectively. In conclusion, CpG adjuvant was found to be superior followed by ISA206 and Poly I:C in eliciting protection in VLP based FMD vaccines in guinea pigs.