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Genetic vaccination of pigs against disease: an evaluation of a combined injection of DNA plasmids coding for cytokines and protective viral antigens

Contract nr: FAIR-CT96-1317
Project nr: 1317
Project type: SC
Starting date: 01/01/1997
Duration: 42 months
Total cost: 1,329,183 EUR
EC Contribution: 1,041,083 EUR
Scientific Officer: Isabel MINGUEZ-TUDELA
Research topic: Animal health

The Foot-and-Mouth Disease (FMD) virus was selected because FMDV stock vaccines are still required in case of epizootiological emergency in Europe. Production of an FMDV vaccine requires high containment facilities and would obviously benefit from a new, non-infectious, and therefore safer and inexpensive vaccination strategy using only bacterial plasmids. In addition, protective antigens have already been defined (FMDV protein VP1), which will facilitate evaluation of the vaccination of pigs using DNA plasmids coding for this antigen.

The project will evaluate the efficiency of genetic vaccination against the economically most significant viral disease, FMD, directly in the pig, using a combined injection of naked DNA plasmids containing DNA coding for immunostimulatory porcine cytokines and for viral protective antigens. A major goal is to assess the effects of cytokine expression, following DNA injection, on the development of anti-viral immunity and, ultimately, protection against viral challenge.

Because separate immune mechanisms, such as neutralising antibodies and cell-mediated immunity, are potentially involved in protection from viral diseases, another viral infection will also be studied in the project, in comparison to FMDV: pseudorabies (PRV or Aujeszky's disease virus). Protection to this viral infection is known to involve primarily cell-mediated immunity, while protection to FMDV is mainly antibody-mediated. Plasmids coding for PRV glycoproteins, including gB, gC, and gD, as protective immunogens will be used. FMDV and PRV are therefore complementary infections suitable for assessing cytokine modulation of the Thl/Th2 balanced control of the antiviral immune response. In the proposed project, plasmids will be constructed containing DNA under the control of potent promoters, coding for FMDV VP1 (or PRV gp), or either of the porcine cytokine interferon (IFN alpha, IFN beta, IFN gamma), interleukin-2 (IL2), IL-4, IL-12 and granulocyte-macrophage colony stimulating factor (GM-CSF). The plasmid constructs will first be evaluated in transfection systems in vitro, and then in vivo in pigs, after intramuscular (i.m.) - and in some cases via a subcutaneous - injection. The in situ tissue expression of cytokines (both at the mRNA and protein levels) will be evaluated at the site of injection of plasmids. Pigs receiving plasmids with viral immunogens DNA will be sequentially examined for the appearance of circulating anti-viral neutralising antibodies and T-cell reactivity to the relevant viral antigens. Furthermore, the plasmids with DNA coding for viral antigens will be injected in pigs, together with different combinations of cytokines, and the stimulatory effects of the cytokine plasmids on development of relevant types of protective antiviral immunity will be examined. From these experiments the potentially most efficient combinations of cytokine and antigen encoding plasmids will be selected and injected into pigs. Protective immunity against FMDV in these animals will be tested in challenge experiments.

Current situation/results:
Several new plasmids have been obtained, coding for several FMDV candidate immunogens, and for porcine cytokines. They were all shown to be expressed in vitro. Vaccination trials in pigs have shown the ability of FMDV DNA constructs (and PRV constructs) to induce specific immune responses, including antibody and T-cell responses. More importantly, injections of DNA coding for porcine GM-CSF in combination with DNA coding for FMDV (and PRV) immunogens, increased the efficacy of DNA vaccination, as evidenced by increased protection from the viral challenge infection.

Domaine de Vilvert
F-78352 Jouy-en-Josas
Tel.: +33 1 34 65 26 20
Fax: +33 1 34 65 26 21


  • Gunnar ALM
    Swedish University of Agricultural Sciences
    Biomedical Center
    P.O. Box 588
    S-751 23 Uppsala
    Tel.: +46 18 17 45 33
    Fax: +46 18 17 43 82

  • Jean-Christophe AUDONNET
    Rue Marcel Merieux 254
    P.O. Box 7009
    F-69342 Lyon
    Tel.: +33 4 72 72 34 85
    Fax: +33 4 72 72 34 97

  • Robert PARKHOUSE
    Institute for Animal Health
    Ash Road
    UK-GU24 0NF Pirbright - Woking
    Tel.: +44 1483 23 24 41
    Fax: +44 1483 23 24 48

  • Francisco Javier DOMINGUEZ JUNCAL
    Jose Abascal 56
    E-28130 Valdeolmos
    Tel.: +34 916 20 23 00
    Fax: +34 916 20 22 47

  • Emmanuel ALBINA
    Rue des Fusillés
    B.P. 53
    F-22440 Ploufragan
    Tel.: +33 2 96 76 01 30
    Fax: +33 2 96 78 68 61

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