Abstract
The human milk (HM) microbiota is a significant source of microbes that colonize the infant gut early in life. The aim of this study was to compare transient and mature HM virome compositions, and also possible changes related to the mode of delivery, gestational age, and weight for gestational age. Overall, in the 81 samples analyzed in this study, reads matching bacteriophages accounted for 79.5% (mainly Podoviridae, Myoviridae, and Siphoviridae) of the reads, far more abundant than those classified as eukaryotic viruses (20.5%, mainly Herpesviridae). In the whole study group of transient human milk, the most abundant families were Podoviridae and Myoviridae. In mature human milk, Podoviridae decreased, and Siphoviridae became the most abundant family. Bacteriophages were predominant in transient HM samples (98.4% in the normal spontaneous vaginal delivery group, 92.1% in the premature group, 89.9% in the C-section group, and 68.3% in the large for gestational age group), except in the small for gestational age group (only ~45% bacteriophages in transient HM samples). Bacteriophages were also predominant in mature HM; however, they were lower in mature HM than in transient HM (71.7% in the normal spontaneous vaginal delivery group, 60.8% in the C-section group, 56% in the premature group, and 80.6% in the large for gestational age group). Bacteriophages still represented 45% of mature HM in the small for gestational age group. In the transient HM of the normal spontaneous vaginal delivery group, the most abundant family was Podoviridae; however, in mature HM, Podoviridae became less prominent than Siphoviridae. Myoviridae was predominant in both transient and mature HM in the premature group (all C-section), and Podoviridae was predominant in transient HM, while Siphoviridae and Herpesviridae were predominant in mature HM. In the small for gestational age group, the most abundant taxa in transient HM were the family Herpesviridae and a species of the genus Roseolovirus. Bacteriophages constituted the major component of the HM virome, and we showed changes regarding the lactation period, preterm birth, delivery mode, and birth weight. Early in life, the HM virome may influence the composition of an infant’s gut microbiome, which could have short- and long-term health implications. Further longitudinal mother–newborn pair studies are required to understand the effects of these variations on the composition of the HM and the infant gut virome.
Highlights
Breastfeeding is considered a gold standard in infant nutrition, as it has been adapted to provide for the demanding growth of the newborn in a time-dependent way with a wide range of components including macronutrients, micronutrients, and bioactives [1,2]
The Human milk (HM) microbiota is a significant source of microbes that colonize the infant gut early in life, promote the growth of beneficial microbiota, aid in the maturation of the innate and adaptive immune systems, provide protection against gastrointestinal infections, and may help to form both short- and long-term infant health outcomes through metabolic programming, immunomodulation, and neuromodulation [4,5,6,7,8]
This study aims to evaluate the HM virome composition with detailed metagenomic analysis, to compare transient and mature human milk, and to evaluate possible changes related to preterm birth, delivery mode, and birth weight for gestational age
Summary
Breastfeeding is considered a gold standard in infant nutrition, as it has been adapted to provide for the demanding growth of the newborn in a time-dependent way with a wide range of components including macronutrients (fat, proteins, and carbohydrates), micronutrients, and bioactives [1,2]. Breastfeeding boosts the immune system, enhances neurodevelopment, and can have an effect on the development of noncommunicable diseases and conditions later in life [1,3]. Human milk (HM) bioactives such as the HM microbiota have been shown to provide healthy gastrointestinal mucosal stimuli, influence the gut microbiota composition, and promote the development of the infant’s immune system [4,5]. The HM microbiota is a significant source of microbes that colonize the infant gut early in life, promote the growth of beneficial microbiota, aid in the maturation of the innate and adaptive immune systems, provide protection against gastrointestinal infections, and may help to form both short- and long-term infant health outcomes through metabolic programming, immunomodulation, and neuromodulation [4,5,6,7,8]. The HM microbiota is an infinite source for the infant gut microbiota as long as breastfeeding is maintained [1]
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