Origin of Lipids in Influenza Virus

Purified preparations of some animal viruses have been found consistently to contain lipids as an integral part of their structure (see reviews by Smadel and Hoagland, 1942; Hoagland, 1943; Beard, 1948, 1951; Sharp, 1953; and Knight, 1949, 1954). The lipid content and composition of individual viruses appear to be fairly constant and reproducible, but the values vary widely from one virus to another (Table 1). It was recognized at an early date that the viral lipids were in a “bound” form, probably as lipo-nucleoprotein complexes (Hoagland et al. 1940). Thus, extraction of vaccinia with benzene or ether (McFarlane and Macfarlane, 1939; Hoagland et al., 1940), and of influenza virus with petroleum ether (Taylor, 1944) removes only small amounts of lipid (chiefly cholesterol) with little loss of viral infectivity, whereas polar solvents (alcohols) readily effect complete extraction of the lipids with complete loss of viral infectivity. Furthermore, Hoagland et al. (1940)...