Crystal structure of an anti-idiotype variable lymphocyte receptor

Abstract

Variable lymphocyte receptors (VLRs), the leucine-rich repeat (LRR)-based antigen receptors of jawless fish, have great utility in a wide variety of biochemical and biological applications, similar to classical Ig-based antibodies. VLR-based reagents may be particularly useful when traditional antibodies are not available. An anti-idiotype lamprey VLR, VLR39, has previously been identified that recognizes the heavy-chain CDR3 of the B-cell receptor (BCR) of a leukemic clone from a patient with chronic lymphocytic leukemia (CLL). VLR39 was used successfully to track the re-emergence of this clone in the patient following chemotherapy. Here, the crystal structure of VLR39 is presented at 1.5 Å resolution and compared with those of other protein-specific VLRs. VLR39 adopts a curved solenoid fold and exhibits substantial structural similarity to other protein-binding VLRs. VLR39 has a short LRRCT loop that protrudes outwards away from the concave face and is similar to those of its protein-specific VLR counterparts. Analysis of the VLR39-BCR interaction by size-exclusion chromatography and biolayer interferometry using the scFv version of the BCR confirms that VLR39 recognizes the BCR Fv region. Such VLR-based reagents may be useful for identifying and monitoring leukemia in CLL patients and in other clinical diagnostic assays.

Lamprey Variable Lymphocyte Receptor Monoclonal Antibodies for Whole-Cell Surface Antigens

“…A variety of monoclonal VLR antibodies have been successfully generated against diverse classes of antigens including purified proteins [7], cell surface determinants [8,9], anti-idiotypic antibody targets [10], glycan antigens [11,12], extracellular matrix antigens [13], viral antigens [14], and bacterial cell wall antigens [15], demonstrating the practical potential of VLR antibodies. The lamprey immune response has been characterized, [16] and this information has been incorporated into inoculation schemes designed to optimize monoclonal selection.…”

“…Size variation upon testing a random library clones is consistent with the capture of a diverse set of clones during library preparation. High background in empty vector control: If background staining with the secondary Ab is high, a different secondary Ab reagent should to be used 10…”