Antibiotic Conditioning and Single Gavage Allows Stable Engraftment of Human Microbiota in Mice

Mice transplanted with human microbiota are essential tools for studying the role of microbiota in health and disease, striving for the development of microbiota-modulating therapeutics. Traditionally, germ-free mice have been the principal option for establishing human microbiota-associated (HMA) mouse models, leading to significant insights into the composition and function of the human microbiota. However, there are limitations in using germ-free mice as recipients of human microbiota, including considerable resource allocation to establish and maintain the model and incomplete development of their immune system and physiological functions. Thus, antibiotic-treated, non-germ-free mice have been developed as an alternative to satisfy the growing demand for an accessible HMA mouse model. Several methods have been described for creating "humanized" mice. These protocols vary in their key components, mainly antibiotic conditioning and frequency of oral gavage. To address this practical challenge and formulate a simple and repeatable protocol, we established a HMA mouse model with antibiotic-treated conventional and specific-pathogen free (SPF) C57BL/6J mice, revealing that a single oral gavage allows stable engraftment of the human microbiota. In this chapter, we present our simple protocol for antibiotic conditioning to prepare mice for stable engraftment of human gut microbiota.