Unified mass-action theory for virus neutralization and radioimmunology.

All ideas implicit in the papers since 1953 involved in applying mass-action thermodynamics to antibody-antigen reactions are unified by the use of: (a) the intermediary concept of extent of reaction; (b) the concept of intrinsic association constant; (c) a statistical analysis for probable complexes; and (d) identification of the complex or complexes that contribute to the bioassay. Several general theoretical examples are given that show the limitations of linear interpretations of equilibrium data. Two practical examples from the literature illustrate foot-and-mouth disease virus and influenza virus neutralization.