Dramatic improvement in FMD DNA vaccine efficacy and cross-serotype antibody induction in pigs following a protein boost.

To overcome the low and slow development of humoral antibody often observed with DNA vaccines we applied a prime-boost strategy. When FMD DNA vaccine P1-2A3C3D and pGM-CSF primed pigs were boosted with inactivated foot-and-mouth disease virus (FMDV) antigen and recombinant 3D (without adjuvant) an average 36-fold increase in the FMDV antibody response was observed compared to conventional vaccination, that included a log(10) virus neutralising titre increase. Most remarkably, a significant level of cross-serotype reactivity was observed against A, C and Asia1 in the virus neutralisation and ELISA tests. This prime-boost strategy fully protected pigs from a heterologous challenge.