Robust and Reproducible Monoclonal Antibody Production Using a Transgenic Silkworm System

Transgenic silkworms are promising host organisms for the production of therapeutic recombinant proteins due to their superior protein synthesis ability and human-like posttranslational modifications. In this study, we generated transgenic silkworms that secrete a recombinant human monoclonal antibody (mAb) against gp120 of human immunodeficiency virus (HIV) into their cocoons. Variations in the rearing temperature and humidity conditions had little effect on mAb properties, such as N-glycosylation. Next, we performed pilot-scale production of the mAb using three batches of transgenic silkworms. Rearing 22,000-45,000 silkworm larvae yielded 4-8 kg of cocoon shells per batch. Larval growth and development, as well as cocoon quality, were highly consistent across production batches. We extracted and purified the mAb from cocoon shells, yielding 6.1-7.6 g of purified mAb per kg of cocoons in each batch. Characterization of the purified mAb showed that the contents of oligomeric antibodies and host cocoon-derived proteins were less than 0.2% and 10 ppm, respectively, with high consistency among batches. From these results, we conclude that the transgenic silkworm system is sufficiently robust and reproducible for high-quality therapeutic mAb production.