42 S. G. ANDERSON 



removed from virus preparations by centrifugatiou, it inactivates the hemag- 

 glutinin at 5°C. in 3 to 4 days (Sabin and Buescher, 1950). Japanese B hemag- 

 glutinin was inhibited also by boiled extracts of Clostridium histolyticwn and 

 CI. lentoputrescens even in dilutions of 10~ 6 , by 1 : 2000 diethyldithiocarba- 

 mate in buffer, and also by zinc sulfate in concentrations of 0'03 to 1.92 fig. 

 per unit of hemagglutinin. Iron, manganese, magnesium, mercury, and 

 copper were not inhibitory (Sabin and Buescher, 1950). 



7. Serological Grouping 



The hemagglutinins have been divided serologically into three groups and 

 it is possible that more groups will be denned later (Casals, 1957; Casals and 

 Brown, 1954). There are cross-reactions between members of any one group 

 but these reactions are slight or absent between groups. Group A includes 

 western, eastern, and Venezuelan equine encephalitis, Semliki Forest, Sindbis, 

 and Mayaro viruses; Group B includes Japanese B, St. Louis, Murray Valley, 

 West Nile, yellow fever, dengue 1, dengue 2, Ilheus, Ntaya, Russian far 

 eastern, Uganda S, and Zika viruses. 



B. Enteroviruses 

 1. GD VII 



a. Hemagglutinin. The GD VII strain of Theiler's virus was described by 

 Theiler and Gard (1940). Lahelle and Horsfall (1949) noted the hemagglutina- 

 tion of human group O cells at 4°C, but not at 23 or 37°C. The virus eluted 

 at 37°C. Hemagglutination occurred in the pH range 4.3 to 8.3. The virus 

 did not agglutinate cells of monkey, horse, sheep, cat, dog, guinea pig, hamster, 

 mouse, or fowl. 



GD VII adsorbed to human cells at 20°C. but did not agglutinate them, or 

 agglutinated them only poorly. However, after treatment of the virus by 

 trypsin, it hemagglutinated at 20°C. (Morris, 1952). Trypsin-treated virus 

 occasionally agglutinated red cells from monkey and guinea pig at 4°C. 



Virus on human red cells eluted at 37°C. without damage to the cells, and 

 again agglutinated the cells on cooling to 4°C. (Fastier, 1950). The receptors 

 involved differed from those to which influenza attached, and periodate ion 

 and RDE of V. cholerae did not affect GD VII hemagglutination. 



GD VII adsorbed to red cells in a salt-free medium at 4 or 18°C, but did 

 not hemagglutinate at 4°C. unless salts were present to a concentration of at 

 least 0.025 M (Fastier, 1951b). Elution into an electrolyte-containing medium 

 was retarded by calcium ions; Lahelle and Ward (1951) found elution to 

 occur into a buffered glucose medium at 4°C. 



The hemagglutinin of GD VII was reduced to 1 % of its initial titer by 

 heating to 56°C. for 30 minutes, but stored well at 4°C. for over a month 

 (Lahelle and Horsfall, 1949). 



