Host-Pathogen Interactions and Immunopathogenesis: Insights into Innate and Adaptive Immune Responses

Understanding the molecular dialogue between invading pathogens and host immune defences is central to developing effective therapeutics and vaccines. This chapter provides a comprehensive review of pattern recognition receptor signalling, inflammasome activation, type I interferon responses, and the orchestration of adaptive immunity in the context of viral, bacterial, fungal, and parasitic infections. It critically analyses mechanisms by which pathogens subvert immune surveillance — including immune evasion strategies, molecular mimicry, and exploitation of regulatory pathways — and explores how dysregulated immune responses contribute to immunopathology, cytokine storm syndromes, and post-infectious sequelae.