IT SHOULD BE POSSIBLE TO OBTAIN MASS PRODUCTION OF FMDV PROTEINS AT LOW COST (BECAUSE THE INSECT CELLS USED FOR THE MULTIPLICATION OF THE BACULOVIRUSES ARE EASY TO CULTIVATE). FMDV IS ECONOMICALLY THE MOST IMPORTANT EUROPEAN ANIMAL DISEASE IN EUROPE. PRESENTLY, MOST COUNTRIES HAVE A POLICY OF SYSTEMATIC VACCINATION OF CATTLE, WHICH IS EFFICIENT BUT VERY EXPENSIVE.
Research has been undertaken to develop a system, utilising highly efficient baculovirus vectors, for making foot and mouth disease (FMD) virus procapsids as the basis of a safe and effective vaccine. Four discrete antibody binding regions on FMD virus were identified. A complementary deoxyribonucleic acid (cDNA) clone of the type C procapsid was prepared. The functions of the 3 virus protease genes were studied by constructing cassettes of serotype O or A procapsid genes with various combinations of protease genes, and expressing them in a cell free translation system or in mammalian cells. Several were also made into baculovirus vectors, including one carrying all 3 protease genes. The latter, when used to infect insect cells, yielded small amounts of FMD virus protein able to self process to procapsid subunits, some of which then assembled into procapsid like structures. Difficulties encountered in trying to increase expression were traced to the toxic L protease, a problem that could be overcome by making deletions in the L gene. A new type of baculovirus vector, identifiable by a simple colour test and able to infect insect larvae, was developed.
THE BACULOVIRUSES ARE SPECIFIC FOR THE CELLS OF SOME INSECTS AND ARE ABLE TO INDUCE THE SYNTHESIS OF A PROTEIN (POLYHEDRIN) IN LARGE QUANTITIES IN INFECTED CELLS (UP TO 25% OF THE TOTAL CELL PROTEIN MASS). THIS PROTEIN IS NON ESSENTIAL FOR THE PRODUCTION OF INFECTIOUS VIRUS IN CELL CULTURE. THE PROJECT IS THE REPLACEMENT OF THE GENES CODING FOR THIS PROTEIN BY GENES CODING FOR IMMUNIZING PROTEINS OF THE FMDV. FRAGMENT OF THE FMVD CDNA ENCODING THE PRECURSOR (P1) OF ALL FOUR CAPSID PROTEINS WILL BE INSERTED INTO A BACULOVIRUS VECTOR, TOGETHER WITH SEQUENCES ENCODING FMDV PROTEINS WHICH MAY PLAY A ROLE IN THE MATURATION OF THE PRECURSOR PROTEIN.
Funding SchemeCSC - Cost-sharing contracts