Expression of a single-chain Fv antibody fragment specific for the hepatitis B surface antigen in transgenic tobacco plants.

An anti-Hepatitis B virus surface antigen (HBsAg) single chain Fv (scFv) antibody fragment was expressed in Nicotiana tabacum transgenic plants. The 6-histidine tagged scFv was targeted to either the cytosol, apoplast, and vacuole, or for retention in the endoplasmic reticulum. Expression of active scFv was detected by ELISA in fresh leaf material from F I transgenic plant lines representative of the genetic constructs targeting the antibody fragment to the apoplastic fluid (AF-12, 0.