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The role of the light chain in the structure and binding activity of two cattle antibodies that neutralize bovine respiratory syncytial virus

DOI: 10.1016/j.molimm.2019.04.026 DOI Help

Authors: Jingshan Ren (University of Oxford) , Joanne E. Nettleship (University of Oxford; Research Complex at Harwell) , Gemma Harris (Research Complex at Harwell) , William Mwangi (The Pirbright Institute) , Nahid Rhaman (University of Oxford; Research Complex at Harwell) , Clare Grant (The Pirbright Institute) , Abhay Kotecha (University of Oxford) , Elizabeth Fry (University of Oxford) , Bryan Charleston (The Pirbright Institute) , David I. Stuart (University of Oxford) , John Hammond (The Pirbright Institute) , Raymond J. Owens (University of Oxford; Research Complex at Harwell)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Molecular Immunology , VOL 112 , PAGES 123 - 130

State: Published (Approved)
Published: August 2019
Diamond Proposal Number(s): 10627 , 14744

Open Access Open Access

Abstract: Cattle antibodies have unusually long CDR3 loops in their heavy chains (HCs), and limited light chain (LC) diversity, raising the question of whether these mask the effect of LC variation on antigen recognition. We have investigated the role of the LC in the structure and activity of two neutralizing cattle antibodies (B4 and B13) that bind the F protein of bovine respiratory syncytial virus (bRSV). Recombinant Fab fragments of B4 and B13 bound bRSV infected cells and showed similar affinities for purified bRSV F protein. Exchanging the LCs between the Fab fragments produced hybrid Fabs: B13* (B13 HC/B4 LC) and B4* (B4 HC/B13 LC). The affinity of B13* to the F protein was found to be two-fold lower than B13 whilst the binding affinity of B4* was reduced at least a hundred-fold compared to B4 such that it no longer bound to bRSV infected cells. Comparison of the structures of B4 and B13 with their LC exchanged counterparts B4* and B13* showed that paratope of the HC variable domain (VH) of B4 was disrupted on pairing with the B13 LC, consistent with the loss of binding activity. By contrast, B13 H3 adopts a similar conformation when paired with either B13 or B4 LCs. These observations confirm the expected key role of the extended H3 loop in antigen-binding by cattle antibodies but also show that the quaternary LC/HC subunit interaction can be crucial for its presentation and thus the LC variable domain (VL) is also important for antigen recognition.

Keywords: Respiratory syncytial virus (RSV); Bovine; Variable domains; Antibody

Subject Areas: Biology and Bio-materials


Beamlines: I03-Macromolecular Crystallography , I04-1-Macromolecular Crystallography (fixed wavelength) , I24-Microfocus Macromolecular Crystallography

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