INFECTIOUS BURSAL DISEASE VIRUS STRUCTURAL PROTEINS EXPRESSED IN A BACULOVIRUS RECOMBINANT CONFER PROTECTION IN CHICKENS

Plasmids were prepared that contained cDNA segments of the large genom ic segment A of infectious bursal disease virus (IBDV) strain GLS-5. T he genes encoding the IBDV structural proteins (VP2, VP3 and VP4) were introduced into the baculovirus transfer vector pB1ueBacI to obtain a recombinant baculovirus vIBD-7. When insect cells were infected with recombinant viruses, the result was synthesis of IBDV precursor protei ns which were processed by the viral protease. The recombinant IBDV an tigens were characterized by immunoprecipitation with monoclonal antib odies (MAbs) and polyclonal antiserum to IBDV, and by antigen-capture ELISA using a panel of IBDV-specific MAbs. The recombinant IBDV antige ns closely resembled the native IBDV proteins and reacted with all the GLS-5 strain-specific neutralizing MAbs that recognize only conformat ional epitopes of IBDV. When susceptible chickens were inoculated with the recombinant IBDV antigens, virus-neutralizing antibodies were ind uced that conferred up to 79% protection against IBDV challenge.