A germ-free humanized mouse model shows the contribution of resident microbiota to human-specific pathogen infection

Germ-free (GF) mice, which are depleted of their resident microbiota, are the gold standard for exploring the role of the microbiome in health and disease; however, they are of limited value in the study of human-specific pathogens because they do not support their replication. Here, we develop GF mice systemically reconstituted with human immune cells and use them to evaluate the role of the resident microbiome in the acquisition, replication and pathogenesis of two human-specific pathogens, Epstein-Barr virus (EBV) and human immunodeficiency virus (HIV). Comparison with conventional (CV) humanized mice showed that resident microbiota enhance the establishment of EBV infection and EBV-induced tumorigenesis and increase mucosal HIV acquisition and replication. HIV RNA levels were higher in plasma and tissues of CV humanized mice compared with GF humanized mice. The frequency of CCR5(+) CD4(+) T cells throughout the intestine was also higher in CV humanized mice, indicating that resident microbiota govern levels of HIV target cells. Thus, resident microbiota promote the acquisition and pathogenesis of two clinically relevant human-specific pathogens. Resident microbiota contribute to HIV and EBV infection in a germ-free humanized mouse model.

Automated summary

Germ-free mice are commonly used in studying the role of the microbiome in health and disease, but they are not suitable for studying human-specific pathogens. In this study, a germ-free mouse model systemically reconstituted with human immune cells was developed and used to evaluate the role of the resident microbiome in the acquisition, replication, and pathogenesis of Epstein-Barr virus (EBV) and human immunodeficiency virus (HIV). The results showed that the resident microbiome enhances the establishment of EBV infection, EBV-induced tumorigenesis, mucosal HIV acquisition, and replication.