Induction of a protective response in swine vaccinated with DNA encoding foot-and-mouth disease virus empty capsid proteins and the 3D RNA polymerase

Abstract

This work focuses on the development of a potential recombinant DNA vaccine against foot-andmouth disease virus (FMDV). Such a vaccine would have significant advantages over the conventional inactivated virus vaccine, in particular having none of the risks associated with the high security requirements for working with live virus. The principal aim of this strategy was to stimulate an antibody response to native, neutralizing epitopes of empty FMDV capsids generated in vivo. Thus, a plasmid (pcDNA3.1/P1-2A3C3D) was constructed containing FMDV cDNA sequences encoding the viral structural protein precursor P1-2A and the non-structural proteins 3C and 3D. The 3C protein was included to ensure cleavage of the P1-2A precursor to VP0, VP1 and VP3, the components of self-assembling empty capsids. The non-structural protein 3D was also included in the construct in order to provide additional stimulation of CD4 M T cells. When swine were immunized with this plasmid, antibodies to FMDV and the 3D polymerase were synthesized. Furthermore, neutralizing antibodies were detected and, after three sequential vaccinations with DNA, some of the animals were protected against challenge with live virus. Additional experiments suggested that the antibody response to FMDV proteins was improved by the co-administration of a plasmid encoding porcine granulocyte-macrophage colony-stimulating factor. Although still not as effective as the conventional virus vaccine, the results encourage further work towards the development of a DNA vaccine against FMDV.

Foot-and-Mouth Disease

“…One approach utilized a DNA inoculationbased strategy designed to produce empty capsids in inoculated animals (46,52,91,95). Similar studies using cDNA that encodes the entire viral genome but contains a mutation at the cell binding site were also performed (46,471).…”

Attenuated Foot-and-Mouth Disease Virus RNA Carrying a Deletion in the 3′ Noncoding Region Can Elicit Immunity in Swine

“…These vaccines have proven useful in preventing the disease but present important constraints, such as the risk of virus escape from production plants and the difficulty in distinguishing infected animals from uninfected vaccinates. New vaccine strategies aimed at overcoming these problems have been developed, including subunit vaccines consisting of VP1 protein or chemically synthesized peptides (57,61), different DNA constructs expressing viral immunogens (6,8,15), and recombinant viruses (25,35,44,54,63). Live attenuated candidate vaccines for FMD lacking the leader L protease and mutations in the receptor binding sequence RGD have also been proposed (3,16 …”

Granulocyte-macrophage colony-stimulating factor does not increase the potency or efficacy of a foot-and-mouth disease virus subunit vaccine

“…To enhance the immune response induced by Ad5-O1C, we tested a vaccination regimen that included co-administration of pGM-CSF, a cytokine that has been shown to enhance the immune response of animals to some vaccines (Xiang & Ertl 1995, Lee et al 1998, Somasudaran et al 1999, Cedillo-Barrón et al 2001, Barouch et al 2002. We constructed an Ad5-pGMCSF virus that expressed biologically active pGM-CSF.…”

“…Cedillo- Barrón et al (2001) demonstrated that the addition of plasmid encoded pGM-CSF along with a DNA based FMDV empty capsid vaccine resulted in a statistically significant increase in the antibody levels against FMDV and somewhat improved the protection of vaccinated swine as compared to swine only given the empty capsid vaccine. However, in these studies the swine were challenged after 3 DNA inoculations and the increase in FMDV-specific antibody levels was only detected after the second inoculation.…”

“…Several approaches are being used to develop alternative FMD vaccines that address these concerns, including construction of modified live-virus , Almeida et al 1998, biosynthetic proteins (Kleid et al 1981, McKercher et al 1985, synthetic peptides (Bittle et al 1982, Clark et al 1983, Brown 1988, Blanco et al 2001, naked DNA vectors (Ward et al 1997, Chinsangaram et al 1998, Wong et al 2000, Benvenisti et al 2001, Cedillo-Barrón et al 2001, and recombinant viruses (Sanz-Parra et al 1999a,b, Mayr et al 1999, Berinstein et al 2000, Moraes et al 2002, Wu et al 2003b). However, most of these approaches have either been unsuccessful in both swine and cattle or require multiple inoculations to induce protection.…”