Expression of a Gene for
Single-chain Antibody to Carcinoembryonic Antigen in Bombyx mori cells and
Its Larvae
LI Biao1,2, ZHU Cheng-Mo1, YANG
Wei-Dong1,2 and WU Xiang-Fu2
( 1Rui Jin Hospital, Shanghai No.2 Medical University,
Shanghai 200025, China； 2Shanghai Institute of Biochemistry, the
Chinese Academia of Sciences, Shanghai 200031, China )
Abstract Recombinant
Bm-BacScFv virus which contains a cDNA encoding anti-CEA single-chain antibody
was generated by cotransfection into Bm N cells with the transfer plasmid
pBacPAK-(His)6-ScFv and the modified Bombyx mori nuclear
polyhedrosis virus Bm-BacPAK genomic DNA. Bombyx mori cells and larvae
were infected by the recombinant virus, respectively. The anti-CEA single-chain
antibody were expressed both in Bombyx mori cells and larvae, the
former accounted for 6% of the total cell protein, the later 0.3 mg per larvae.
The histidine-tagged ScFvs were respectively purified with nickel-iminodiacetic
acid affinity chromatography. The purity of the former reached over 90% and
that of the latter was lower. Purified protein products was able to bind to CEA
with an affinity constant of 5.4×108/mol・L-1 and 2.3×108/mol・L-1,
slightly lower than its parental monoclonal antibody E7B10
which had 2.7×109/mol・L-1.
Key Words carcinoembryonic antigen； single-chain antibody； expression； baculovirus expression system
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