Studies on the Inactivation of Influenza and Newcastle Disease Viruses by a Specific Lipid Fraction of Normal Animal Sera

Abstract

A lecithin-like fraction of sera from seven different animal sources appears capable of inactivating in vitro four different strains of influenza virus and one strain of Newcastle disease virus. This material is effective in concentrations so low as to exclude any possible participation of the extracting materials; the inactivating effect appears to be peculiar to serum lipids. The inactivation of the infective property of these viruses occurs at 37 C but not at a room temperature of 24 C; it is proportionate to the time of exposure; it is not hastened by increasing the amount of material present; and it is not significantly affected by changes in the pH in the range of 5 to 9. The inactivating material does not affect the hemagglutinating property of active or heat-inactivated influenza virus. The inactivating effect is inhibited by solutions of alpha amino acids and imino acids with the exception of the dicarboxylic acids, glutamic and aspartic acids. The evidence for and against the positive identification of this material as lecithin is discussed.