Host Resistance Assays
Introduction: Host resistance assays, the gold standard of immunotoxicity testing, are a powerful approach to evaluate global functional capacity in a fully interactive immune system. Host resistance assays based on the clearance of a replicating infectious agent provide a critical overview of how well the innate, adaptive, and homeostatic regulatory immune functions are integrated to protect the host. Both comprehensive as well as targeted host resistance assays are available, each with distinct purposes. Comprehensive host resistance models, used to determine whether an immunotoxic effect is present, and targeted host resistance models, designed to addresses mechanistic questions pertaining to the immunological armamentarium, provide valuable insight into the complexity surrounding the effect of dose on the induction of a protective immune state. The sections that follow describe host resistance models based on challenge with viruses, bacteria and parasites. Each provides an overview of how the various assays may be used, along with a summary of procedures.