Figure 1. Illustration of the concept of stoichiometries and the parameters used in the model.

The sketch in panel (A) depicts a virion with spikes each consisting of three identical subunits. Thus, each spike has binding regions for one type of monoclonal antibodies. The virion has spikes bound to 0 antibodies, spikes bound to 1 antibody, and spikes bound to 2 and 3 antibodies, respectively. Under the assumptions that the stoichiometry of entry is and the stoichiometry of neutralisation is , the virion is still infectious because it has nine spikes with fewer than two antibodies bound. Panel (B) shows several virions that are neutralised or infectious according to the definition of stoichiometries.