Troybodies and pepbodies.

ABSTRACT

All antibodies (Abs) with effector function are produced in mammalian cells, whereas bacterial production is restricted to smaller targeting fragments (scFv and Fab) without effector functions. In this project, we isolated different peptides that bind one of several Ab effector molecules. We have developed bacterial expression vectors for direct cloning of these peptides as fusions to scFv and Fab, and have obtained targeting fragments that also have the ability to bind Ab effector molecules. Some of these fusions (pepbodies) may also initiate Ab effector functions. We have also genetically inserted T-cell epitopes into Abs with specificity for antigen-presenting cell (APC) surface molecules to target the Ab-T-cell epitope fusions (Troybodies) to APCs. The approach is to exchange loops in Ig constant domains with single copies of well-defined T-cell epitopes. We have shown that a number of such T-cell epitopes are loaded on to MHC class II on APCs and are presented to specific T-cells. An increase in T-cell activation of up to four orders of magnitude is achieved compared with synthetic peptide. Our current goal is to identify all the loops in all Ig constant domains that may be loaded with T-cell epitopes to produce a multi-vaccine.