CpG DNA enhances the immune responses elicited by the DNA vaccine against foot-and-mouth disease virus in guinea pigs

CpG DNA is DNA sequence that has immune stimulatory effects. Several tines of Investigation over the past few years indicate that CpG DNA plays an imp ortant role in the induction of immune responses to DNA vaccines. In this s tudy, CpG DNA-containing synthetic oligodeoxynucleotide (CpG-ODN) was clone d into the eukaryotic expression plasmid encoding a fusion protein containi ng beta- galactosidase from E. coli and immunogenic epitopes of foot-and-mo uth disease virus (FMDV) type O, and the immune responses induced by the pl asmid were assayed. The results showed that guinea pigs immunized with the recombinant plasmid containing CpG-ODN generated a higher level of FMDV-neu tralizing antibody and a stronger T cell proliferative response and protect ion against viral challenge than those receiving the plasmid containing no CpG-ODN. Our study demonstrated that it is an effective route to enhance th e efficacy of DNA vaccines by inserting exogenous CpG DNA into the plasmids , and the DNA vaccine developed here Is a promising candidate to prevent FM DV infection.