When developing vaccines or antiviral therapeutics it is important to identify the viral antigen or proteins responsible for the infection. Scientists will perform a viral protein binding and inhibition assay to screen a library of antibodies that can inhibit viral protein binding to the host cells. By allowing the target antibodies to interact with the viral antigen and host cells, the level of binding inhibition effects can be determined.
A high-throughput inhibition assay to study MERS-CoV antibody interactions using image cytometry
There are currently 7 coronaviruses including the new emerging SARS-CoV-2 that are known to infect humans.
The emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) poses serious threats to global public health and highlights the urgent need to rapidly identify and characterize potential neutralizing antibodies. MERS-CoV resulted in 2,494 confirmed infections and 858 deaths in 2019 globally at a high mortality rate of 35 – 40%.
For MERS-CoV virions, the spike (S) proteins are present on the surface and mediate viral entry, thus making it the primary target for MERS-CoV vaccine and antibody development. The S proteins consist of S1 and S2 subunits, where the S1 region includes the RBD and NTD domains and can bind to the host cell receptor dipeptidyl peptidase-4 (DPP4). There is a need to identify monoclonal antibodies with broad neutralization activity towards RBD, NTD, and S2 binding sites.
Zhang, Naru et al. “Receptor-binding domain-based subunit vaccines against MERS-CoV.” Virus research 202 (2015): 151-9.
MERS-CoV display spike (S) proteins contain S1 and S2 subunits
Common methods for the detection of protein binding
Some of the commonly serological methods like ELISA, biolayer interferometry, and flow cytometry are used to study MERS-CoV antibody binding specificity and function.
Enzyme-Linked Immunoassay (ELISA)
ELISA is unable to assess antibody binding to antigen in their native conformation. In addition, unlimited access to epitopes may exaggerate antibody binding results, which can generate false-positive results.
Biolayer interferometry is limited by the requirement of tagged protein to immobilize to affinity tip. This detection method also may reduce sensitivity and reproducibility due to the difficulty in detecting bound proteins.
Flow cytometry can be time-consuming and tedious, which may not be practical for screening purposes. The system typically requires management by highly trained specialists, on-going maintenance by service engineers.