Targeting of influenza epitopes to murine CR1/CR2 using single-chain antibodies

Single-chain variable fragment (scFv) antibodies are genetically engineered molecules comprising the variable regions responsible for specific binding . scFv that recognize certain surface molecules on professional antigen pre senting cells could therefore be suitable for targeting Ag to these cells. We have produced an scFv that recognizes murine complement receptors 1 and 2 (CR1/CR2) and genetically fused it with different numbers of influenza he magglutinin peptides which contain both B and T cell epitopes. The CR1/CR2 specific hybridoma 7G6 was used for RT-PCR to obtain the variable regions, which were then combined to create an scFv fragment. The influenza hemagglu tinin intersubunit peptide HA317-41 (IP) was engineered to the N terminus o f the scFv in one, two or three copies. The so obtained IP(1-3)7G6scFv stil l bound the complement receptors; the peptides in the construct were recogn ized by the peptide specific monoclonal IP2-11-1 on Western blots and ELISA s. The CR1/CR2 positive B lymphomas A20 and 2PK3 presented the peptide to a n I-E-d restricted IP specific T cell hybridoma more efficiently when incub ated with the IP(1)7G6 constructs as compared to the free peptide. The resu lts suggest that scFv could work as targeting devices in subunit vaccines. (C) 1999 Elsevier Science B.V. All rights reserved.