ROLE OF MILK WHEY IN THE TRANSMISSION OF HUMAN CYTOMEGALOVIRUS-INFECTION BY BREAST-MILK

Breast-fed infants are susceptible to human cytomegalovirus (HCMV) inf ection via breast milk In our previous study, HCMV was isolated more f requently from breast milk at later than one month after delivery than from colostrum or early breast milk To clarify the role of milk cells and whey in vertical infection by breast feeding, we separated breast milk into milk cells and whey and examined each fraction for the pres ence of HCMV. We collected breast milk from mothers who breast-fed the ir infants (aged from 3 days to 2 months). The breast milk was centrif uged and separated into the middle layer (layer of milk whey) and the pellet (containing milk cells). We attempted to isolate HCMV from whey and to detect HCMV immediate early (IE) DNA in both milk whey and cel ls. HCMV was isolated from 7 out of 35 (20.0%) whey samples and HCMV I E DNA was detected from 15 out of 35 (42.9%) whey and/or milk cells. D etection rates of HCMV IE DNA in the whey layer and milk cells were 39 .1% (25 out of 64) and 17.2% (11 out of 64), respectively. HCMV IE DNA was not detected in colostrum, but was detected in breast milk sample s one month after delivery. Therefore, cell-free HCMV shed into milk w hey may have a more important role in vertical infection by breast mil k than cell-associated HCMV in the milk.