Functional recombinant antibodies against human chorionic gonadotropin expressed in plants

Single-chain variable fragments, diabodies and chimeric antibodies (mouse variable domains and human immunoglobulin constant domains) were engineered by DNA recombinant technique and expressed transiently in tobacco leaves. The plants expressed the three types of antigen-binding moieties, accurately and faithfully. The yield obtained was 32 mg, 40 mg and 20 mg respectively, per kg of wet weight of leaves. The chimeric antibody had high affinity for human chorionic gonadotropin (Ka = 1.9 x 10 1 0 M - 1 ). All three forms of the recombinant antibodies expressed by plants inhibited the binding of hCG to receptor on Leydig cells.