Embracing microbial exposure in mouse research

: Research using mouse models have contributed essential knowledge toward our current understanding of how the human immune system functions. One key difference between humans and typical laboratory mice, however, is exposure to pathogens in their respective environments. Several recent studies have highlighted that these microbial encounters shape the development and functional status of the immune system. For humans, such numerous and unavoidable encounters with viruses, bacteria, and parasites may be a defining factor in generating a healthy and robust immune system, poised to respond to new infections and to vaccination. Additionally, the commensal organisms that make up the host microbiome also change with environment and impact the immune response. Hence, there is a pressing need to generate more faithful mouse models that reflect the natural state of the human immune system. This review explores the use of new experimental mouse models designed to better understand how host-microbial interactions shape the immune response. By embracing these technologies to complement traditional mouse models, researchers can remove a significant barrier that has long separated murine and human immunologists.