DNA vaccine (P1-2A-3C-pCDNA) co-administered with Bovine IL-18 gives protective immune response against Foot and Mouth Disease in cattle

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals causing considerable economic loss in the affected countries. Presently used tissue culture inactivated vaccine protects the vaccinated animals for a short duration. DNA vaccines along with appropriate adjutants is one of the approach for the development of alternative vaccine. In the present study, we constructed P1-2A-3CpCDNA (containing P1-2A-3C coding sequences of FMDV Asia-1 Ind 63/72) and bovine IL-18 pCDNA plasmids and evaluated in cattle. Four groups of calves each group containing six calves were vaccinated with 200 μg of plasmid DNA vaccine P1-2A-3CpCDNA, P1-2A-3CpCDNA+ bIL-18pCDNA and inactivated vaccine respectively where as fourth group was unvaccinated. P1-2A-3CpCDNA + bIL-18pCDNA vaccinated animals have shown higher levels of neutralizing antibodies and specific T-cell proliferation responses. Higher levels of CD4⁺ and CD8⁺ cells were observed in these animals. Similarly, IL-18 adjuvanted group has shown increased Th1 and Th2 cytokine responses. All the vaccinated animals were challenged with cattle adapted FMD homologous Asia1 virus two weeks after the booster dose. IL18 co administered DNA vaccine construct has protected four out of six animals challenged with homologous virus.