Inactivation of hepatitis C virus infectivity by human breast milk.

BACKGROUND: 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 infectiousness. METHODS/RESULTS: Human breast milk reduced HCV infectivity in a dose-dependent manner. This effect was species-specific because 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. CONCLUSIONS: 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.

Environmental Stability and Infectivity of Hepatitis C Virus (HCV) in Different Human Body Fluids.

Background: Hepatitis C virus (HCV) is a hepatotropic, blood-borne virus, but in up to one-third of infections of the transmission route remained unidentified. Viral genome copies of HCV have been identified in several body fluids, however, non-parental transmission upon exposure to contaminated body fluids seems to be rare. Several body fluids, e.g., tears and saliva, are renowned for their antimicrobial and antiviral properties, nevertheless, HCV stability has never been systematically analyzed in those fluids. Methods: We used state of the art infectious HCV cell culture techniques to investigate the stability of HCV in different body fluids to estimate the potential risk of transmission via patient body fluid material. In addition, we mimicked a potential contamination of HCV in tear fluid and analyzed which impact commercially available contact lens solutions might have in such a scenario. Results: We could demonstrate that HCV remains infectious over several days in body fluids like tears, saliva, semen, and cerebrospinal fluid. Only hydrogen-peroxide contact lens solutions were able to efficiently inactivate HCV in a suspension test. Conclusion: These results indicate that HCV, once it is present in various body fluids of infected patients, remains infective and could potentially contribute to transmission upon direct contact.