This detailed volume explores numerous multidisciplinary approaches employed to analyze the role of different molecules or strategies used by different guests to survive inside hosts. Divided into several sections, the book delves into animal-pathogen interaction, microbe-microbe interaction, as well as plant-pathogen interaction. Written for the highly successful Methods in Molecular Biology series, chapters include brief introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls.