A new study published in Nature further strengthen the evidence of the role of breast milk against viral infections during the neonatal period.
Human gut is devoid of viruses at birth. Viral colonization in neonatal gut is found to occur in a stepwise manner influenced by breast feeding.
A metagenomic study of neonatal gut microbes involving two US cohorts and one African cohorts proved this finding. The investigators examined stool samples of neonates at 0-4 days, 1 month and 4 months for virus like particles (VLPs). The VLPs were few or undetectable in meconium samples (0-4 days). At 1 month of age, the VLP count increased to 109 per gram and persisted at the age of 4 months. This was almost close to the VLP count in adults concluding that the high VLP count seen at 1 month of age in neonates persist into adulthood. According to the study the type of VLP at 4 months were different from 1 month. At one month the VLP included prophages of pioneer bacteria that invade the neonatal gut at birth. At 4 months the VLP predominantly represented the viruses that replicate in humans. This study also showed that multiple human viruses were more abundant in the gut of infants who are exclusively formula fed compared to the infants exclusively breastfed and fed with both formula and breast milk at 4 months.
Metagenomics involves sequencing all DNA extracted from a sample followed by assembly of sequence reads or mapping them to a reference database followed by annotation of the genes. The Handbook of Metabolic Phenotyping, 2019
Investigators conclude that early life viral colonization is stepwise, with the first phase characterized by induction of phages from pioneer bacteria and a second phase of colonization with viruses that infect human cells which is modulated by breastfeeding.
The study shed light on the extent of subclinical infection and the diversity of causative organisms in infants and strengthens the current evidence on importance of breastfeeding in protecting against viral infections. Hence all health authorities should promote protect and support – the natural mechanism of protection against diseases- breastfeeding.