New short-term heat inactivation method of cytomegalovirus (CMV) in breast milk: impact on CMV inactivation, CMV antibodies and enzyme activities.

OBJECTIVES: Breast milk (BM) is the primary source of cytomegalovirus (CMV) transmission to premature infants with potentially harmful consequences. We therefore wanted to evaluate temperature and duration of short-term BM pasteurisation with respect to CMV inactivation, effect on CMV-IgG antibodies and BM enzyme activities.

METHODS: 116 artificially CMV-spiked BM and 15 wild-type virus-infected samples were subjected for 5 s to different temperatures (55°C-72°C). CMV-IE-1 expression in fibroblast nuclei was assessed using the milk whey fraction in short-term microculture. BM lipase and alkaline phosphatase (AP) activities and CMV binding using CMV-recomLine immunoblotting and neutralising antibodies using epithelial target cells were analysed before and after heating.

RESULTS: A minimum of 5 s above 60°C was necessary for CMV inactivation in both CMV-AD-169 spiked and wild-type infected BM. Lipase was very heat sensitive (activities of 54% at 55°C, 5% at 60°C and 2% at 65°C). AP showed activities of 77%, 88% and 10%, respectively. CMV-p150 IgG antibodies were mostly preserved at 62°C for 5 s.

CONCLUSION: Our results show that short-term pasteurisation of BM at 62°C for 5 s might be efficient for CMV inactivation and reduces loss of enzyme activities, as well as CMV binding, and functional CMV antibodies.