THE COURSE OF INFECTIOUS DISEASE 



In recent years two advances in knowledge seem to justify 

 a further look at the possible significance of this resemblance. 

 In the first place measles virus has now been grown by 

 Enders and Peebles (1954) in tissue culture, where it produces 

 distinct intranuclear inclusions. The second reason is the 

 recognition of a syndrome of giant-cell measles pneumonia 

 as a rare fatal termination of measles presumably due to some 

 anomaly of immunological response. The only histological 

 evidence of measles in the incubation period is the presence 

 of Warthin-Finkeldey giant cells in lymphoid tissue, and it is 

 in line with all the available facts to assume that during the 

 incubation period measles virus is present in mesenchymal 

 cells. 



With this rather slender basis of fact and deduction it may 

 be interesting to speculate on the nature of the process that 

 culminates in the symptomatic onset of measles 12 to 14 days 

 after infection. We can postulate that a virus particle is taken 

 up by mesenchymal cells to initiate infection. Multiplication 

 is relatively slow and infection of other cells is initially con- 

 fined to mesenchymal types. 



It is not easy to picture the process in detail but one could 

 suggest that a large part of the virus multiplication during 

 the incubation period is intracellular without necrosis and 

 that this acts as a stimulus to proliferation of at least a pro- 

 portion of the mesenchymal cells concerned. In this way we 

 can imagine the development of an extensive population of 

 'measles cells' which can pass like other mesenchymal cells 

 to various parts of the body where their presence is recogniz- 

 able by the proportion which have taken on the Warthin- 

 Finkeldey giant cell form (Hertzberg, 1932; MuUigan, 

 1944). Concomitantly an immunological response is de- 

 veloping — clones of appropriately patterned cells are 

 proliferating, initially at least, as non-antibody producers 

 for the most part. At some point an unstable situation 

 develops which we may picture as immunological contact 

 (of cell or globuUn) with measles cells resulting in liberation 



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