Mich B. Hein

Plant virus expressing hybrid coat protein with added murine epitope elicits autoantibody response.

A modified tobacco mosaic virus (TMV) was used to direct the synthesis of TMV coat protein hybrids containing a 13 amino acid sequence of the murine zona pellucida ZP3 protein. This hybrid protein was found to be robust and accumulate to high concentrations in inoculated plants. Virus-like particles containing the hybrid coat protein could be readily purified from infected plant tissue. Parenteral immunization with these virus-like particles as antigen resulted in serum antibody recognizing ZP3 epitope in C57BL/6J and BALB/cBy mice. The antibodies recognized synthetic ZP3 peptide and the authentic murine ZP3 glycoprotein. Antibodies were recruited in vivo to the zone pellucida in female mice.

Immunotherapeutic potential of antibodies produced in plants

Plants are capable of synthesizing and assembling virtually every kind of antibody molecule, ranging from the smallest antigen-binding domains and fragments, to full-length, and even multimeric, antibodies. A number of plant hosts can be used, and because this is a versatile expression system that can be scaled-up to agricultural proportions, a cheap and plentiful supply of antibodies could be made available. Immunotherapy is one of the many potential uses for bulk quantities of antibody. In particular, passive immunotherapy of mucosal surfaces may be possible, because functional secretory antibodies can be engineered in plants.

Assembly of Antibodies and Mutagenized Variants in Transgenic Plants and Plant Cell Cultures

Antibody molecules, taken out of the context of the vertebrate immune system, are complex glycosylated proteins with high binding specificities for antigens. The variety of possible antigens is virtually limitless. Specific antibodies can be elicited from the mammalian immune system that have high affinity for synthetic organic molecules, as well as for naturally occurring organic compounds.