Inhibition of Influenza Virus Hæmagglutination by a Brain Lipid Fraction

THERE exists a rather ill-defined group of complex lipids that could be subsumed under the name of ‘mucolipids’. These substances, while possessing constituents commonly considered characteristic of the cerebrosides, share some properties with the mucoproteins. Thus, they are soluble in water and include amino-sugars and a nitrogen-containing acid which gives rise to a violet colour with Bial's reagent and to a colour reaction with p -dimethylamino-benzaldehyde without previous treatment with alkali. We shall here refer to the substance yielding a direct Ehrlich reaction as ‘direct chromogen’, since we are not in a position to decide whether we are dealing with sialic acid 1 , which was first isolated from submaxillary gland mucin 2 , or with neuraminic acid 3 found in a group of lipids later designated as ganglio-sides 4 ; nor indeed whether these two compounds differ.