HEMAGGLUTINATION BY ANIMAL VIRUSES 27 



37°C, but not at 4°C, even after 4 weeks in the presence of 0.08 % formalde- 

 hyde. A concentration of 0.2 % formaldehyde destroyed 98 % of NDV 

 hemagglutinin after 6 days at 4°C. (Chu, 1948d). 



h. Urea. Tyrrell and Horsfall (1954) destroyed the hemagglutinin of PR8 

 and other strains of influenza with 5 M urea acting at 37°C. for several hours. 



j. Glycerol. In concentrations of 10 % to 50 %, glycerol protected the 

 hemagglutinin of PR8, NDV, and mumps against deterioration in the presence 

 of 0.1 % formalin at 4, 23, and 37°C. (Cabasso et al, 1951). Fraser (1957) used 

 50 % glycerol to protect the hemagglutinin of the influenza strain NWS 

 against destruction by heat at 56°C. for 30 minutes. Under these conditions 

 the virus developed the indicator state. 



k. Ether. There are considerable discrepancies in the experience of different 

 workers who have treated myxoviruses with ether. Time and temperature are 

 obviously important and there may be strain differences. It is possible that 

 the presence of impurities has been responsible for some of the findings. 



Hoyle (1952), using strain DSP (isolated in 1943), produced a small 

 particle hemagglutinin of increased titer but with greatly reduced enzymatic 

 activity. Smith et al. (1953) found that PR8 hemagglutinin was destroyed by 

 ether treatment over many hours and could not demonstrate any increase in 

 hemagglutinin even with briefer treatment. 



Using pure reagents, both Schafer and Zillig (1954) and Ada and Burnet 

 (unpublished) have obtained hemagglutinin in a form smaller than the 

 elementary body. The latter showed that preparations from several strains 

 were active both as hemagglutinin and enzyme. 



m. Alcohol and Alum. The hemagglutinins of PR8, NDV, and other strains 

 may be concentrated and purified by precipitation with methanol or ethanol 

 in the cold under carefully specified conditions (Cox et al., 1947). Alum will 

 also precipitate the hemagglutinin without damage (Bodily et al., 1943). 



5. Effect on Red Cells of Physical and Chemical Agents 



a. Aging. Miller and Stanley (1944) confirmed the finding of Hirst that 

 chick cells gave a lower titer of hemagglutinin as they aged over a period of 

 4 to 9 days. 



b. Heating. Red cells heated at 56 or 65°C. were still able to absorb PR8, 

 and red cell stroma heated at 85°C. for 30 minutes still absorbed nearly half 

 the amount of virus that was absorbed by unheated stroma (Hirst, 1948a). 



c. Hydrogen Ion Concentration. Within the range of pH 3.14 to 10.15, red 

 cell receptors were stable for one hour in citrate-phosphate buffer (Hirst, 

 1948a). 



d. Periodate Ion. Hirst (1948a) first stated that concentrations of sodium 

 periodate down to M/1000, acting on 0.75 % fowl red cells, destroyed their 

 ability to absorb virus. Various other oxidizing agents were without effect. 



