摘要Bifidobacterium longum subsp.infantis is a commensal bacterium that predominates in the infant gut,playing a critical role in both preventing foreign infections and facilitating immune development.This study aimed to explore the effects of B.longum subsp.infantis supplementation on interferon-beta(IFN-β)secretion and intestinal barrier improvement in growing mice.Female and male mice were orally administered either saline or B.longum subsp.infantis CCFM1269 or I5TI(1 × 109 CFU/mice per day,n=8)from 1-week-age until 3-,4-,and 5-week-age.RNA sequencing analysis revealed that CCFM1269 exhibited potential antiviral capacity through increasing 2'-5'oligoadenylate synthetase(OAS).Additionally,CCFM1269 supplementation significantly increased colonic IFN-β levels which combined with OAS in 3-week-old female and male mice by activating the TLR4-TRIF-dependent signaling pathway.However,this effect was not observed in 4-and 5-week-old mice.Furthermore,both CCFM1269 were found to modulate the gut microbiota composition and enhance the intestinal barrier function in 3-,4-,and 5-week-old mice.In summary,the results of this study suggested that B.longum subsp.infantis CCFM1269 promoting intestinal barrier and releasing IFN-β in growing mice was in a strain-specific and time-dependent manner.