CLONING AND CHARACTERIZATION OF CDNAS ENCODING V-H AND V-L OF A MONOCLONAL ANTI-CEA ANTIBODY (CEA-79) CROSS-REACTIVE WITH NCA-95 AND GENERATION OF A SINGLE-CHAIN FV MOLECULE (SCFV)

We cloned complementary DNA (cDNA) encoding the variable regions of he avy chain (V-H) and of light chain (V-L,) of a monoclonal anti-carcino embryonic antigen (CEA) antibody cross-reactive with nonspecific cross -reacting antigen-95 (NCA-95), which had been previously prepared and designated as CEA 79 (gamma(2a),,, kappa). From these cDNAs, a phagemi d expression vector for the CEA79 single chain variable fragment (scFv ) was generated. Enzyme-linked immunosorbent assay (ELISA), competitiv e ELISAs, and Western blotting confirmed that the scFv displayed on th e surface of the bacteriophage had retained affinity for CEA and NCA-9 5. We then determined the nucleotide sequences of the cloned cDNAs for V-H, and V-L,. The sequence analysis revealed that V-H, and V-L, of t he CEA 79 antibody represent new members of the mouse heavy chain subg roup ''miscellaneous'' and the kappa light chain subgroup ''V'', respe ctively.