Humanization and mammalian expression of a murine monoclonal antibody against Venezuelan equine encephalitis virus.

The murine monoclonal antibody 1A4A1 can strongly neutralize Venezuelan equine encephalitis virus and is a good candidate for development of humanized antibody. Humanization of 1A4A1 variable domains was achieved by grafting 1A4A1 complementarity-determining regions (CDRs) onto the frameworks of human immunoglobulin germline variable and joining gene segments, whose CDRs have the highest similarities to 1A4A1 ones. The humanized 1A4A1 variable domains were further grafted onto human heavy and light chain constant domains to assemble the whole antibody gene, which was then synthesized and cloned to an adenoviral vector. After expression in HEK 293 cells and purification by protein L column, the humanized antibody was demonstrated to retain antigen-binding specificity and neutralizing activity.