Microwave Treatment Prevents Cytomegalovirus Transmission to Preterm Infants through Human Milk

Background: Mother’s own milk (MOM) is the best nutrition for preterm infants; however, milk from cytomegalovirus (CMV)-seropositive mothers may cause the transmission of the virus to the infants. As extremely preterm infants are at a risk of developing serious conditions due to CMV infection, even MOM is sometimes pasteurized. Previously, we demonstrated that microwave heating of 50 mL formula milk containing CMV at 500 W for 40s prevented CMV infection in living cells. However, we do not know if this is the case with reactivated CMV in human milk (HM). Therefore, we investigated if microwave heating of HM would be effective in preventing CMV infection in living cells. Methods: Twenty-three CMV-IgG-positive and four CMV-IgG-negative mothers who donated HM to the human milk bank during 6 to 16 weeks postpartum were enrolled. The HM was treated with microwave at 500 W. HFL-III cells were seeded in culture dishes. Aliquots of HM samples subjected to microwave was inoculated onto susceptible cell monolayers. Infectious vial titer was measured by the 50% median tissue culture infectious Dose (TCID50) assay. Results: The TCID50 assay was decreased in five out of eight 100-mL samples after microwave at 200W for 60 s. The CMV infectivity assay was negative in three, decreased in eight, and no change in six 100-mL samples, and negative in four and decreased in eight 50-mL samples. Conclusions: Microwave heating of HM at low settings could decrease CMV transmission through HM, however, to obtain entire prevention is difficult when loss of bioactive properties is considered.