APPLICATION OF THE HUMAN HEPATITIS-B VIRUS CORE ANTIGEN FROM TRANSGENIC TOBACCO PLANTS FOR SEROLOGICAL DIAGNOSIS

Background and objectives: The aim was to produce HBcAg from plants mo re cheaply than can be done by other currently available means, and to apply such antigen to immunoassay procedures for pretransfusion testi ng of donor blood. Materials and methods: Transgenic Nicotiana tabacum cv. SR-1 plants expressing the human hepatitis B virus (HBV) core ant igen (HBcAg) gene were generated by Agrobacterium-mediated transformat ion. The recombinant product, called tHBcAg, can assemble itself into a spherical particle with a diameter of 25 to 30 nm, and can maintain two antigenic determinants of HBcAg, namely HBc/alpha and HBc/beta. Pa rtly purified tHBcAg was used in the hemagglutination-inhibition (HI) test, as routinely used by the Japanese Blood Center, to test a panel of 524 blood units taken from HBV-positive donors. Results: In the HI test, tHBcAg showed serologic properties comparable to that from Esche richia coli, the standard antigen used in the Japanese Blood Center. C onclusions: Transgenic plants can produce reagents for serologic testi ng and perhaps even such medical materials as oral vaccines.