Natural disease models use specific pathogens and their native hosts to model the interactions between hosts and pathogens in the appropriate biological context. This helps to understand the immunopathogenesis, analyze the virulence factors and their roles in invasion, penetration, and toxicity as well as host’s immune responses to pathogens. In addition, such models also allow the identification of specific molecules which are often required by the pathogen for infection or subsequent disease induction, and which often represent the targets for the host's immune response. https://www.creative-biolabs.com/vaccine/vaccine-assessment-in-vivo-assays.htm