Efficacy of plant-produced recombinant antibodies against HCG

Abstract

Background: Antibody engineering facilitates the construction of different antibody formats [single chain variable fragment (scFv), diabody, full-size chimeric monoclonal antibody] with ease. Methods: We constructed recombinant antibodies against HCG, which is widely used in pregnancy testing and is also produced by a number of cancers. Results: The recombinant antibodies were transiently expressed in tobacco leaves to levels of up to 40 mg of pure protein per kg fresh leaf weight. Enzyme linked immunosorbent assay (ELISA) and electrophoretic mobility assay (EMSA) confirmed antibody specificity for the beta subunit of β-HCG. The efficacy was confirmed by inhibiting HCG induced testosterone production by Leydig cells in vitro and by blocking the HCG induced increase in mouse uterine weight in vivo. Conclusions: Passive immunization with recombinant HCG-specific antibodies may have clinical utility as (i) diagnostic and therapeutic tools for HCG-expressing cancers and (ii) contraceptive measures.