142 THE PHYSICS OF VIRUSES 



constant corresponding to AH^ = 159,000 and AS^ = 370 

 (these figures are only approximate), whereas 40% has a slowly 

 changing constant with AH^ = 17,400 and AS = —22.5 (again 

 only roughly). These two types of inactivation are identified 

 with the two antigens found from deuteron and'^ electron bom- 

 bardment, the large antigen corresponds to the slowly changing 

 constant and the small to the rapidly changing one. It may be 

 coincidence, but the values for T-1 phage agree rather well, 

 both in target size and AW, with SBMV. Clearly, many more 

 such studies need to be made to see if this is a general type of 

 antigen. 



Hemagglutination 



Some of the phenomena which can be so effectively studied in 

 the interaction of phage and bacterium can be looked into by ob- 

 serving hemagglutination. This is a phenomenon discovered by 

 Hirst (1942) which takes place for a fair variety of red cells and a 

 moderate number of animal viruses, notably influenza, New- 

 castle disease, and mumps. Studies comparable to those of Puck, 

 Garen, and Cline should be possible, although they have not 

 yet been carried out. We are here concerned with two physical 

 studies of hemagglutination, the work "of Lauffer and Miller 

 (1944) on influenza virus, and some recent work by Woese in 

 the author's laboratory on the action of ionizing radiation on 

 Newcastle disease virus. 



In the experiments already quoted in Chapter 2, Lauffer 

 and Miller showed that, for influenza virus, infectivity and re- 

 fractive index move in the same way. The fact that this virus 

 also possesses the property of agglutinating red blood cells 

 enables a test to be made of the identity of the physical, infec- 

 tive, and agglutinating units. The calculated sedimentation rate 

 from boundary measurement is compared with the agglutination 

 activity above the barrier in the sedimentation cell with the 

 results shown in the table. It can be seen that hemagglutination 

 follows the boundary in a very satisfactory way. Agglutination 

 is thus an inherent property of this virus. The figures for in- 

 fectivity and nitrogen content are shown for comparison. 



