Avidity of Polyclonal Antibodies to Foot-and-Mouth Disease Virus in Bovine Serum Measured Using Bio-Layer Interferometry

Abstract

Foot-and-mouth disease (FMD) is a disease of cloven-hoofed livestock caused by FMD virus (FMDV). FMD can be controlled through the use of inactivated vaccines, and it is well established that the protection afforded by FMD vaccines correlates strongly with neutralising antibody titres. However, the overall strength of binding, referred to as avidity, is also an important parameter with respect to the ability of antibodies to neutralise virus infection, and there is evidence that avidity can affect the level of protection afforded by FMDV vaccines. Here, as an alternative to modified enzyme-linked immunosorbent assays (avidity ELISAs) incorporating a chaotropic wash step, we used bio-layer interferometry (BLI) to measure the avidity of bovine polyclonal antibodies against FMDV capsids. We conducted preliminary experiments using recombinant FMDV capsids, as well as peptides representing antigenic loops, to demonstrate that the binding of monoclonal antibodies targeting specific antigenic sites could be detected using BLI. Subsequent experiments using polyclonal sera derived from FMD vaccinated cattle provided evidence of a positive correlation between the neutralising titre of the serum and the avidity as measured by BLI. Furthermore, we observed an increase in BLI avidity, as well as in the titre, in vaccinated animals upon challenge with the live virus.

Binding and Avidity Signatures of Polyclonal Sera From Individuals With Different Exposure Histories to Severe Acute Respiratory Syndrome Coronavirus 2 Infection, Vaccination, and Omicron Breakthrough Infections

“…We then analyzed whether avidity would correlate with neutralization by means of other, perhaps more sensitive methods. Biolayer interferometry (BLI) is typically used to assess the affinity of monoclonal antibodies, and the dissociation rate has been used as surrogate for the avidity of polyclonal serum samples using BLI [ 22 ]. We standardized the conditions for measuring this response in polyclonal serum samples using Niquel 2+ -nitriloacetic acid sensors that capture the recombinant RBD or spike by binding to their hexa-histidine tag.…”

Screening of immunogenic proteins and evaluation of vaccine candidates against Mycoplasma synoviae

“…The collected sera were isolated after centrifugation (3000 × g , 15 min), and their antibody titers were determined using an indirect ELISA assay as described above. The rabbit sera immunized with M. synoviae were dialyzed using Binding Buffer (0.15 M NaCl, 20 mM Na 2 HPO 4 , pH 7.0), and then purified by Protein A/G affinity chromatography according to the manufacturer’s instructions (Solarbio, Beijing, China) 40 . The IgGs were salted out with ammonium sulfate using a protocol previously described in ref.…”

Novel antigenic proteins of Mycoplasma synoviae as potential vaccine candidates

“…Rabbit sera immunized with M. synoviae was dialyzed with Binding Buffer (0.15 M NaCl, 20 mM Na2HPO4, pH 7.0), and then purified by Protein A/G affinity chromatography according to the manufacturer's conditions (Solarbio, Beijing, China) 42 . For saltingout of IgGs with ammonium sulphate using the protocol described previously 43 .…”