Transgenic tobacco cells producing the human monoclonal antibody to hepatitis B virus surface antigen.

The recombinant human monoclonal antibody (MAb) against hepatitis B virus (HBV) surface antigen (HBsAg) was expressed in tobacco suspension cultures. The parental CL4MAb was produced by the Epstein-Barr virus (EBV) transformed human cell line TAPC301-CL4. The CL4MAb cDNA was introduced into tobacco suspension cells by Agrobacterium mediated transformation. The monoclonal antibodies (MAbs), B294 and B303, which were derived from CL4 and subsequently produced in plant cells were selected for study. After purification on Protein A columns, B294 and B303 MAbs had anti-HBs relative affinity constants similar to the parental CL4MAb. B303 MAb interacted with cell surface HBsAgs and showed complement-dependent cytotoxicity in a manner that was similar to anti-HBs human immunoglobulins (HBIg) that are used clinically. The results of this study point to the feasibility of producing MAbs to HBsAg in plants as an alternative to HBIg.