30 S. G. ANDERSON 



viruses or with the bacterial receptor-destroying enzyme of V. cholerae, a 

 gradient can be demonstrated. 



b. Altered Electrophoretic Mobility. After stabilization of cells by virus, the 

 electrophoretic mobility of the cell is reduced to a figure which is character- 

 istic of the virus used. The extent of reduction of electrophoretic mobility 

 in general correlates with the position of the strain in the receptor gradient. 

 The mobility of human cells is normally 1.3 /z/sec. /volt/cm.; cells stabilized 

 by mumps have a value of 1.18; MEL, 0.80; BEL, 0.75; PR8, 0.74; LEE, 0.74; 

 MIL B, 0.67; NDV, 0.50; and swine, 0.37. 



The effect of swine and NDV on electrophoretic mobility is unexpectedly 

 great; the mobility has become lower than expected from their place in the 

 gradient (Ada and Stone, 1950). On the basis of this and other observations, 

 Stone and Ada (1950) suggested that NDV and swine both have two distinct 

 actions on the red cell. One action determines their place in the gradient: 

 both actions contribute to reduction in electrophoretic mobility of the cell. 

 They also believe that the receptor-destroying enzyme (RDE) of V. cholerae 

 has the same two actions on red cells. They believe both these actions are 

 mediated by an enzyme. If this is accepted, it follows that each of these 

 viruses possesses two distinct enzymes, or more probably that there are two 

 or more substrates available to a single virus enzyme. 



c. The Development of New Antigens on the Red Cell Surface. Following 

 Thomsen's recognition (1927) of the panagglutinability of human red cell 

 suspensions contaminated by certain bacteria, Friedenreich (1928) treated 

 human red cells with diphtheroids and vibrios, and found that the cells 

 become agglutinable by any normal serum. The responsible serum com- 

 ponent was called a T agglutinin. Similarly, following treatment of red cells 

 by myxoviruses or RDE, the cells developed T agglutinogens. The T agglut- 

 inin titer estimated in serum varied according to the strain of virus used to 

 treat the cells, being greater with viruses further down the gradient. With 

 swine-treated fowl cells, the titer was about 1 : 160 (Burnet et al., 1946). 



Burnet and Anderson (1947) demonstrated that human or guinea pig cells 

 treated with RDE of V. cholerae and injected into rabbits stimulated the 

 production of new red cell agglutinins to high titer. These new agglutinins 

 reacted with both normal red cells and cells treated with either RDE or 

 viruses of the myxo virus group. The agglutinins for treated cells were not 

 absorbed from the serum by normal cells. Stewart and Quilligan (1951) found 

 a comparable antigenic modification of red cell surface by PR8 and LEE. 



d. Special Characters of Cells Treated with NDV or Mumps Virus. New- 

 castle disease virus and mumps virus agglutinate red cells in normal fashion 

 but have several additional effects not seen with influenza viruses. Their 

 capacity to show an extension of hemagglutinin titer when kept in contact 

 with cells at 37°C. has already been mentioned. When red cells are treated 



