Preservation of Anti-cytomegalovirus Activity in Human Milk Following High-Pressure Processing Compared to Holder Pasteurization

Abstract

Pasteurized donor human milk is recommended for hospitalized preterm infants when mother’s own milk is unavailable. Our aim was to compare the antiviral activity of human milk processed by Holder pasteurization (HoP) or high-pressure processing (HPP) against representative enveloped and non-enveloped viruses including cytomegalovirus and hepatitis A virus. Expressed milk from 20 donors collected from the Ontario Milk Bank was combined into 10 pools, each from two unique donors. Each pool was processed by HoP (62.5°C, 30 min) or HPP (500 MPa, 8 min, 4°C) and subsequently inoculated with cytomegalovirus or hepatitis A virus to achieve a final concentration of 5-log plaque-forming units/mL. Plaque reduction assays were used to quantify detectable virus after 30 min incubation (room temperature). Post hoc experiments using a 4 h incubation time were conducted if reductions were detected at 30 min. Irrespective of processing, cytomegalovirus concentrations declined in all pools after 30 min incubation (P < 0.0001). Milk processed by HoP exhibited significantly less reduction compared to raw milk (P = 0.0069). In post hoc experiments, anti-cytomegalovirus activity was maintained at 4 h, with high inter-pool variability. Hepatitis A virus concentration remained unchanged after 30 min incubation in raw and processed milk. Anti-cytomegalovirus activity in human milk is preserved following HoP and HPP, persisting up to 4 h post-inoculation; anti-hepatitis A virus activity was not observed in raw or processed milk. Further research is needed to understand how HoP or promising alternative processing methods affect the antiviral activity of donated milk, given its potential importance to recipient infants.

The Use of Saliva Samples to Test for Congenital Cytomegalovirus Infection in Newborns: Examination of False-Positive Samples Associated with Donor Milk Use

“…A few studies tested donated milk samples for CMV prior to pooling and pasteurization [ 24 , 25 ]. Bacterial and viral analysis of unpasteurized individual milk from an internet sharing source ( n = 101) compared to unpasteurized individual samples of milk donated to a milk bank ( n = 20) found that 21% of the internet samples were CMV DNA positive versus 5% of the human milk bank samples [ 25 ].…”

New alternatives to holder pasteurization in processing donor milk in human milk banks

“…Pitino et al ( 48 ) reported the reduction of CMV (initial load of 10 5 PFU/mL) and hepatitis A virus (HAV) (initial load of 10 6 PFU/mL) below the detection limit (4 PFU/mL) for multiple HPP treatment tested (350–600 MPa; 8–10 min). Furthermore, Kothari and colleagues ( 47 ) reported a maintained anti-CMV activity in milk treated by one HPP-cycle of 500 MPa for 8 min. Therefore, HPP used in these conditions preserves antiviral activity.…”