B. Infantis Supplementation to Improve Immunity in Infants Exposed to HIV

The primary objectives of this study are to evaluate the effect of early-life B. infantis Rosell®-33 supplementation in infants exposed to HIV on: * gut microbiome composition and diversity at 4 weeks of life * markers of intestinal inflammation and microbial translocation at 4 weeks of life * Th1 cytokine responses to BCG at 7 weeks and 36 weeks of life The secondary objectives include to evaluate the effect of B. infantis Rosell®-33 supplementation on: * longitudinal succession of the gut microbiota composition, diversity and function * relative and absolute abundance of B. infantis in infant stool during the first 36 weeks of life * stool metabolome * T cell subset ontogeny during the first 9 months of life. Exploratory objectives are to evaluate whether B. infantis Rosell®-33 supplementation improves: * infant growth * all-cause morbidity * neurodevelopment during the first 9 months of life * antibody responses to early childhood vaccines