Gut Microbiota Shifts in Pup Athymic BALB/c Mice: An Updated Identification in Nude Mice

SIMPLE SUMMARY: Mammal gut microbiota has been gradually considered to be related to innate and adaptive immunity. Incredibly, although athymic nude mouse is one of the most popular animals for modeling immunodeficiency and tumors, a basic understanding of its gut microbiota has still not been attained, and current relevant conclusions are controversial. In this 30-day study, based on high-throughput sequencing technology, we compared the differences in gut microbial community structures and functions between normal and nude pup mice, and concluded that gut microbiota shifts did occur in nude mice. These findings provide updated insight for the nude mouse tumor model. ABSTRACT: It is commonly recognized that immunodeficiency modifies the gut microbiota in mammals. However, little information on the gut microbiota is available for athymic nude mice; one of the most popular animals for modeling immunodeficiency and tumors. In this study, 16S rDNA amplicon sequencing was performed to investigate the gut microbial composition of pup nude BALB/c mice during a 30-day experimental period. In contrast to pup normal mice, pup nude mice showed a significant variation in gut microbiota. Continuously decreased dynamics of the gut bacterial Shannon index, abnormal Firmicutes/Bacteroidetes ratio, the rarity of Bifidobacterium and Lactobacillus species, and a developmental lag of gut bacterial functions were observed in nude mice. The shift in gut microbiota and abnormal colonization of beneficial bacterial species in nude mice provide an updated insight into the nude mouse tumor model and a new perspective for establishing an animal model for study on dysbacteriosis.