The project will evaluate the efficacy of genetic vaccination against the economically most important viral disease, Foot-and-Mouth disease (FMD), directly in the pig, using 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 development of antiviral immunity and ultimately protection against viral challenge. The FMD virus was selected because FMDV stock vaccines are still required in case of epizootiological emergency in Europe. Production of 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.
Because separate immune mechanisms, such as neutralizing antibodies and cell-mediated immunity, are potentially involved in protection to viral diseases, another viral infection will also be studied in the project in comparison to FMDV : pseudorabies (PR ? or Aujeszkyls disease). Protection to this viral infection is known to involve primarily cell-mediated immunity, while protection to FMDV is mainly antibody-mediated. PRV glycoprotein D will be used as protective immunogen. FMDV and PRV are therefore complementary infections suitable for assessing cytokine modulation of the Thl/Th2 balanced control o 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 gD), or either of the porcine cytokine interferon-~ (IFN--), IFN-~, IFN--, interleukin-2 (IL2), IL-4, IL-12 and granulocytemacrophage 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 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 antiviral neutralizing 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 potentiall 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.
Funding SchemeCSC - Cost-sharing contracts
GU24 0NF Woking
751 23 Uppsala