Inactivation of Hepatitis C Virus Infectivity by Human Breast Milk
was an interesting study that looked at breast milk and the
transmission of HCV. The authors concluded that human breast milk has
antiviral properties against the hepatitis C virus that prevent the
transmission of HCV. This study adds important information about the
lack of HCV transmission via breast milk and what in breast milk
inhibits HCV. It also validates the recommendation that HCV positive
mothers can breast feed their babies without risk of HCV transmission.
Pfaender S, et al.
Institute for Experimental Virology, TWINCORE Centre
for Experimental and Clinical Infection Research; a joint venture
between the Medical School Hannover (MHH) and the Helmholtz Centre for
Infection Research (HZI), Feodor-Lynen-Str. 7, 30625 Hannover, Germany.
Hepatitis C virus (HCV) is spread through direct
contact with blood, although alternative routes of transmission may
contribute to the global burden. Perinatal infection occurs in up to 5 %
of HCV infected mothers and presence of HCV RNA in breast milk has
been reported. We investigated the influence of breast milk on HCV
Human breast milk reduced HCV infectivity in a
dose-dependent manner. This effect was species-specific since milk from
various animals did not inhibit HCV infection. Treatment of HCV with
human breast milk did not compromise integrity of viral RNA or capsids,
but destroyed the lipid envelope. Fractionation of breast milk
revealed that the antiviral activity is present in the cream fraction
containing the fat. Proteolytic digestion of milk proteins had no
influence on its antiviral activity whereas prolonged storage at 4 °C
increased antiviral activity. Notably, pretreatment with a lipase
inhibitor ablated the antiviral activity and specific free fatty acids
of breast milk were antiviral.
The antiviral activity of breast milk is linked to
endogenous lipase-dependent generation of free fatty acids which
destroy the viral lipid envelope. Therefore, nursing by HCV-positive
mothers is unlikely to play a major role in vertical transmission.