A bidirectional phage display vector for the selection and mass transfer of polyclonal antibody libraries

An approach to the creation of antigen-specific polyclonal libraries of intact antibodies is presented. A polyclonal library of Fab antibody fragments would be expressed using a phage display vector, and selected for reactivity with an antigen or group of antigens. For conversion into a sublibrary of intact polyclonal antibodies, the selected heavy (H) and light (L) chain variable (V) region gene combinations would be transferred in mass, as linked pairs, to a eukaryotic expression vector which provides immunoglobulin (Ig) constant (C) region genes. To enable this selection and transfer, a bidirectional phage display vector was generated, in which the V region gene pairs are linked head to head in opposite transcriptional orientations. The functionality of this vector was demonstrated by the selection, transfer and expression of linked V region gene pairs derived from an A/J mouse that had been immunized with p-azophenylarsonate (Ars)-coupled keyhole limpet hemocyanin (KLH). As expected, the expressed IgG2b anti-Ars antibodies with selected V region gene pairs were shown to have V region sequences and Ars-binding characteristics similar to those of anti-Ars hybridoma antibodies. The technology presented here has potential for many diagnostic and therapeutic applications. These include the generation of polyclonal antibody libraries against multiple epitopes on infectious agents or cancer cells, and of polyclonal libraries encoding chimeric molecules composed of antibody V regions and T cell receptor C regions.