GENERATION OF AN EXPRESSION LIBRARY IN THE BACULOVIRUS EXPRESSION VECTOR SYSTEM

The construction and screening of a small cDNA library consisting of 2 x 10(4) clones in the baculovirus expression vector system are descri bed. This library consists of antibody heavy chain sequences isolated from the spleen of a mouse immunized with tetanus toroid fragment C. A portion of this library was used to produce a pool of recombinant bac uloviruses which were screened for production of antibody fragments re active to tetanus toroid without prior expression in Escherichia coli. The pool of 30 clones was found to contain at least 6 different popul ations of antibody indicating that diversity existed within the librar y. Positive clones were isolated from the baculovirus system and confi rmed as being capable of producing a tetanus reactive antibody by expr ession as a beta-lactamase fusion protein in E. coli. One of these clo nes was returned to the baculovirus system using a different transfer vector, and tetanus binding reconfirmed. The results presented here sh ow that the concept of the construction and screening of a baculovirus expression library is feasible even with 'difficult' proteins, such a s antibody heavy chain fragments, and that the baculovirus expression vector system has the potential to produce cDNA expression libraries w hich can be screened directly for the desired protein.