The stepwise assembly of the neonatal virome is modulated by breastfeeding

The gut of healthy human neonates is usually devoid of viruses at birth, but quickly becomes colonized, which—in some cases—leads to gastrointestinal disorders1–4. Here we show that the assembly of the viral community in neonates takes place in distinct steps. Fluorescent staining of virus-like particles purified from infant meconium or early stool samples shows few or no particles, but by one month of life particle numbers increase to 109 per...