Characterization and Applications of Plant-Derived Recombinant Antibodies

Expression of foreign proteins in plants has become a standard technique in plant molecular biology. Various plant species have been used to produce mammalian proteins, such as human interferon (
1
) and serum albumin (
2
), as well as murine antibodies. Not only full-size antibodies (
3
–
6
) but also Fab fragments (
7
) and single-chain fragments (scFvs) (
8
,
9
) have been expressed successfully in tobacco or
Arabidopsis
, reaching expression levels as high as 1.3% of the total soluble protein (
3
). ScFvs have also been expressed in plant-suspension cultures at levels of 0.5% total soluble protein (
10
). The feasibility of expressing and targeting recombinant antibodies (rAbs) (
11
,
12
) has been achieved in different compartments of plants, including the cytoplasm (scFvs), endoplasmic reticulum, chloroplasts, and the intercellular space (full-size, scFvs, and single-domain antibodies) for various applications (
3
–
10
). These results indicate the flexibility of the plant system for expression of rAbs, or fragments thereof, in various plant cell compartments.