HEMAGGLUTINATION AS APPLIED TO 

 THE STUDY OF VIRUS INFECTION 



George K. Hirst 

 The Public Health Research Institute of The City of New York, Inc. 



There are ii species of virus known to agglutinate red cells: pneu- 

 motropic viruses, influenza (human, swine), PVM (mouse pneumonia), 

 and strain 1233 (human); dermotropic viruses, variola, vaccinia and 

 ectromelia (pox virus of mice) ; neurotropic viruses, Theiler's virus 

 (enteric and encephalitic disease of mice), encephalomyocarditis virus 

 (endemic rat disease) ; pantropic viruses, fowl plague and Newcastle 

 disease (generalized infections of fowl) and a virus with glandular 

 tropism, mumps. It is obvious that this is a very heterogeneous group 

 of agents in respect to the species of natural host, organ specificity, 

 pathogenicity and virus particle size. The latter varies from very small 

 to very large. Each virus has its own spectrum of red cell species with 

 which it can combine. In a few cases the spectrum is narrow and 

 largely confined to red cells from infectible species. 



Among the viruses which cause hemagglutination there is a con- 

 siderable disparity as to the type of reaction between virus and cell 

 surface. In some cases the type of union is of general interest while in 

 other cases the possibility exists that the union is of relatively little 

 biological significance. In some cases the behavior of red cells and of 

 the natural host cells toward the virus is remarkably similar, and in 

 these instances it is felt that something may be learned from the red 

 cell-virus interaction which may give clews as to the nature of events 

 in the earliest stages of natural infection. One of the advantages of this 

 type of study lies in the fact that infection of red cells does not occur 

 and hence the interaction can be examined without interference from 

 later stages of the growth cycle. The most serious disadvantage of such 

 a model is that any information gained will probably be strictly limited 

 to the earliest phases of the infectious process. 



The foregoing viruses may be divided into two groups on the basis 

 of the type of hemagglutinin. Variola, vaccinia and ectromelia comprise 

 one group in which the hemagglutinin is separable from the active virus 

 particle (Burnet and Boake, 1946). These viruses all form pox on their 

 natural hosts, they are interrelated antigenically and the soluble hem- 

 agglutinin is thought to be a lipid, possibly cephalin (Stone, 1946). In 

 the remainder of the viruses the hemagglutinin has not been dissociated 

 from the virus particle. In the case of mumps, Newcastle disease and 

 influenza viruses (MNI group) there is considerable evidence that the 

 hemagglutinin is a part of the virus particle. Theiler's virus, encephalo- 



