Human cytomegalovirus (CMV) is often transmitted to neonates via breast milk. While it's considered benign for healthy term infants, its impact on milk composition and effects on healthy term infants are unknown. This study examined differences in milk transcriptome and metabolome associated with CMV, and its impact on infant gut microbiome and growth. Results show upregulation of the IDO tryptophan-to-kynurenine pathway in CMV+ milk, decreased *Bifidobacterium* in infants' guts, and opposing CMV effects on growth (kynurenine positively correlated, CMV viral load negatively correlated with weight-for-length). This suggests CMV transmission and/or milk composition changes may modulate full-term infant development.

Kelsey E. Johnson, Nelmary Hernandez-Alvarado, Mark Blackstad, Timothy Heisel, Mattea Allert, David A. Fields, Elvira Isganaitis, Katherine M. Jacobs, Dan Knights, Eric F. Lock, Michael C. Rudolph, Cheryl A. Gale, Mark R. Schleiss, Frank W. Albert, Ellen W. Demerath, Ran Blekhman