Inactivation of human immunodeficiency virus type I in human milk: effects of intrinsic factors in human milk and of pasteurization.

Human milk was inoculated with human immunodeficiency virus type I (HIV-1) or with HIV-1-infected cells in volumes and containers typically used in human milk banks. The inoculated milk was pasteurized at 62.5 degrees C for 30 minutes in a water bath, i.e., conditions currently in use or proposed for human milk pasteurization. The process of HIV-1 inoculation and pasteurization effectively inactivated the infectivity of both cell-free HIV-1 and HIV-1-infected cells. No virus was recovered after the process, even after repeated subculturing in attempts to rescue the virus. Pasteurization reduced the infectious titer of cell-free HIV-1 and HIV-1-infected cells by more than 5 logs and 6 logs respectively. Human milk contains one or more components that inactive HIV-1 but that are not toxic for the cells used to replicate virus. These components have not been identified, but physical and solubility properties are consistent with characteristics of lipids.