Sindbis virus replicase-based dna vaccine construct encoding fmdv-specific multivalent epitope gene: Studies on its immune responses in guinea pigs

Abstract

Foot-and-mouth disease (FMD) is still a perennial global menace affecting livestock health and production. It is imperative to figure out new ways to curb this disease. In this study, a sindbis virus replicase-based DNA vaccine, pSinCMV-Vac-MEG990, encoding a multivalent epitope gene (representing tandemly linked VP1 C-terminal halves of three foot-and-mouth disease virus (FMDV) serotypes) was constructed. In vitro transfection studies in BHK-21 cells revealed that the construct was able to express FMDV-specific antigen but does not overproduce the antigen. Immunization of guinea pigs with the construct at dose rate of 10, 5, 2 and 1μg per animal through intramuscular route showed significant neutralizing antibody induction at all doses against all serotype tested as compared to non-immunized controls. On viral challenge of guinea pigs 4week post-immunization with 1000 GPID50 of FMDV serotype A, it was observed that the immunization not only delayed the appearance and reduced the severity of FMD lesions significantly (P<0.05) but also provided complete protection in several guinea pigs. In fact, two of six and one of six guinea pigs were completely protected in 10 and 5μg immunized groups, respectively. These results suggest that the development of the replicase-based DNA vaccine may provide a promising approach as an alternative vaccine strategy for controlling FMD. © 2012 The Authors. Scandinavian Journal of Immunology © 2012 Blackwell Publishing Ltd.