Reduced toxicity of expression, in Escherichia coli, of antipollutant antibody fragments and their use as sensitive diagnostic molecules

Single-chain antibody; fragments (scAb), specific fur the chlorophenoxy acid herbicide mecoprop, have been expressed and purified from the bacterium Escherichia coli. Co-expression with the colE1-compatible, arabinose-inducible, skp expression vector pHELP1 prevented bacterial lysis and significantly increased both total and functional expression yield. The periplasmic protein, SKP, may have a role as a generic detoxification protein. Surface plasmon resonance (BIAcore 2000) analysis confirmed that the purified scAb retained similar binding kinetics to the monoclonal antibody (Mab) front which it was cloned. In competition ELISA, the bacterial scAb showed the same specificity for mecoprop and a related herbicide, MCPA, as the Mab but an increase in sensitivity for free antigen in all ELISA. formats.

Bacterially expressed antibody fragments provide a simple, sensitive and cost-effective alternative to the traditional production of diagnostic Mabs via tissue culture.