Anti-HCMV activity of colostrum and milk from mothers of preterm infants and role of colostrum-derived exosomes.

transmission of some viral pathogens by breast-feeding is an important risk for pre-term infants since they are more susceptible to develop severe clinical symptoms. Despite human cytomegalovirus (HCMV) is commonly excreted in breast milk from seropositive women, only a low percentage of exposed infants will acquire postnatal CMV infection. this observation points towards a protective effect of breast milk components against HCMV transmission to the breastfed child. the aims of our study were: 1) to assess the anti-HCMV potency of breast milk from a cohort of pre-term mothers at different stages of lactation 2) to evaluate the antiviral role of immune factors of colostrum, like secretory iga, and non immune factors, like exosomes. 3) to evaluate the impact of Holder and HtSt pasteurizations on the antiviral properties of breast milk. the study revealed that all milk samples exerted significant anti-HCMV activity in vitro, although to a different extent and with interpersonal variability. interestingly, colostra from HCMV igg-positive mothers exhibited higher antiviral activity than samples from seronegative mothers. We demonstrated a partial contribution of siga to antiviral activity of colostrum and identified colostrum-derived exosomes as new anti-HCMV constituents of human milk. preliminary data indicate the ability of exosomes to inhibit the attachment of HCMV to cells. finally, we evidenced that Holder pasteurization significantly reduced anti-HCMV activity of breast milk, whereas HtSt did not affect it.