486 W. SCHAFEPv 



Several carbohydrate compounds have been demonstrated in influenza 

 virus (Taylor, 1944, Knight, 1947a). Besides the ribose from RNA, galactose, 

 mannose, fucose, and amino sugar have been identified by chromatographic 

 means in recent investigations (Ada and Gottschalk, 1956; Frommhagen 

 and Knight, 1956). Ada and Gottschalk (1956) as well as Frommhagen and 

 Knight (1956) have reported that glucosamine is present. The total percent- 

 age of carbohydrate, excluding the RNA sugar, is approximately 3 %, 

 according to Frisch-Niggemeyer and Hoyle (1956), or 5-8 %, according to 

 Ada and Gottschalk (1956), and older studies of Knight (1947a). Since 

 heteropolysaccharides of similar composition are always bound to protein, 

 it is suggested that mucoprotein also occurs in the influenza virus particle 

 (Ada and Gottschalk, 1956). The amount of carbohydrate in fowl plague 

 virus seems to be higher than in influenza (Zillig et at., 1955); there has not 

 yet been an analysis of the individual carbohydrates. 



In the earHer studies on the hemagglutination phenomenon made by Hirst 

 (1942), it was observed that influenza virus particles adsorbed onto the 

 surface of red cells eluted spontaneously when the complex was uicubated 

 at 37°C. Thereafter the cells were no longer capable of adsorbing virus 

 particles and hence could not be agglutinated. On the other hand, the eluted 

 virus was completely intact, functionally. Thus it was assumed that a virus 

 enzyme had destroyed the cell receptors responsible for adsorption of the 

 virus particle. Other viruses of the myxovirus group were later found to 

 behave similarly (see Hirst, 1952). A more extensive biochemical investiga- 

 tion of the postulated enzyme became possible when it was found tliat mucins 

 from different sources can inhibit the hemagglutinating efl"ect of the virus 

 particles and that this inhibitor eff"ect can be overcome by Liicubating the 

 mucin-virus mixture at 37°C (see Gottschalk, 1957). From these observations 

 the concept emerged that the particular mucins and the ceUular receptors of 

 the myxoviruses have a common chemical grouping that can be attacked by 

 the virus enzyme. 



Through extensive investigations on influenza virus it was recently proved 

 that the enzyme has the character of a neuraminidase (see Gottschalk, 1957). 



This must be a specific part of the virus particle, because it does not 

 occur in the fluids from wliich the virus is obtained, in the uninfected host 

 cells, or other animal cells. Only some microorganisms e.g. Vibrio cholerae 

 produce a substance with similar enzymatic activity, referred to as receptor- 

 destroying enzyme (RDE) (Burnet and Stone, 1947). The substrate and the 

 action of the neuraminidase will be treated in detail in another volume 

 (vol. ni. chap. 4) of this book. 



The neuraminidase in the infective particles seems to be located m or on 

 the virus-hemagglutinin (Hoyle, 1952; Schafer, 1957b). Since this contains 

 only protein and carbohydrate (Frisch-Niggemeyer and Hoyle, 1956; Zillig 



