Host-Microbe Co-Evolution in Human Health: The Microbiome-Pathobiont Continuum - ABSTRACT Support is requested for a Keystone Symposia conference entitled Host-Microbe Co-Evolution in Human Health: The Microbiome-Pathobiont Continuum organized by Drs. Bana Jabri, Caetano Reis e Sousa and Philippe J. Sansonetti, with scientific programming input from Keystone Symposia. The meeting will take place February 18–21, 2025 at the Fairmont in Banff Springs, Banff, Alberta, Canada. Mammals and microbes have co-evolved over 250 million years and host-microbial interactions are central to health and disease. This meeting will cover how the human immune system responds to pathogens and pathobionts while tolerating the presence of beneficial commensal organisms. Dysregulation of this delicate equilibrium can lead to disease through loss of resistance to pathogens or loss of tolerance to commensals. This meeting aims to build a community of scientists working on pathogens, commensals, microbial sensing, innate immunity, evolution and disease pathogenesis to integrate knowledge and collectively address major questions in the field. The interdisciplinary nature of the meeting and its focus on a diversity of microbial species will give investigators a broader perspective on host-microbial interactions and encourage them to look beyond traditional disciplinary boundaries to advance the treatment and prevention of infectious, immunologic and allergic diseases. In addition, the conference will be held jointly with another Keystone Symposia conference, Human Microbiome: Diversity, Selection and Adaptation, which will support new collaborations geared toward a more comprehensive and integrative understanding of the holobiont.