Effect of antiviral lipids, heat, and freezing on the activity of viruses in human milk.

Semliki Forest virus (SFV), herpes simplex virus type 1 (HSV-1), coxsackievirus B4, and cytomegalovirus (CMV) were added to human milk, which was then subjected to treatments that approximated those required for the decontamination or storage of milk. Boiling was the only treatment that eliminated these viruses from the milk. Pasteurization (at 62.5 C for 30 min) did destroy CMV, but the other viruses could still be detected. All of the viruses except HSV-1 were detectable after the contaminated milk samples had been stored at -15 C for 10 days. SFV, HSV-1, and CMV were also decreased by lipid antiviral activity, which was present in 78% of samples that were obtained on day 5 postpartum. Naturally excreted CMV was detected at the highest levels in milk that lacked this antiviral factor; this CMV also survived freezing for 10 days. Thus, whereas the lipid antiviral activity decreased the level of enveloped viruses, whether they were added to or naturally excreted into human milk, further reduction in the levels of these viruses required heat treatment.