Cell Attachment Domains of the Porcine Epidemic Diarrhea Virus Spike Protein Are Key Targets of Neutralizing Antibodies

Li C, et al., doi: 10.1128/JVI.00273-17, J Virol, 2017

Porcine epidemic diarrhea virus (PEDV) is a coronavirus that causes enteric disease in pigs, resulting in high mortality rates, especially in suckling piglets. PEDV infections have resulted in significant economic losses to the swine industry. The spike (S) glycoprotein on the virion surface plays a key role in the virus cell entry, making it an excellent target for neutralizing antibodies. Described herein is the development and characterization of a panel of neutralizing and non-neutralizing mouse monoclonal antibodies raised against the spike protein’s S1 receptor binding region. The competitive binding of monoclonal antibodies to PEDV S1 antigen was evaluated by the Bio-Layer Interferometry (BLI). A Pall ForteBio Octet QK system equipped with Protein A (ProA) Biosensor probes was used to perform BLI assays. ProA sensor tips were immobilized with PEDV GDU S1-Fc protein. Subsequently, unoccupied sites were blocked using polyclonal feline antibodies. The S1-Fc-loaded sensor tips were exposed to a first antibody until a saturation was reached, followed by exposure to a second antibody. This process was repeated using different pairs of antibodies. The investigation reveals antibody epitope landscape of the PEDV S1 subunit. It also highlights the importance of cell-attachment sites on PEDV spike protein as key targets of potent neutralizing antibodies.

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