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THE PHYSICS OF VIRUSES 



We can now imagine a process about as follows. The original 

 virus invades the host cell, and probably a long nucleoprotein 

 molecular aggregate unwinds and presents a large area of specifi- 

 cally active surface. This starts a strongly competitive system 

 of enzyme manufacture, and possibly also of direct enzymatic 

 action, which sets going a new process of synthesis of virus pre- 

 cursor material, both nucleic acid and protein. The nucleopro- 

 tein units so formed become attracted by Van der Waals attrac- 



FiG. 8.10. Token representation of the process of self-duplication. The 

 nucleoprotein units are attracted to an original chain, aggregate near it to 

 form adjacent chains, experience a change in ionic atmosphere, and are forced 



tion and held in place so that near the original unit a second set 

 of nucleoprotein molecules accumulates. This will grow, but 

 only within the 6-A attractive distance, so that a second, long, 

 thin nucleoprotein is formed. This will continue to thicken and 

 develop as the metabolic processes of the host pile up more 

 nucleoprotein until the thickness of both original and new nu- 

 cleoprotein exceed about 200 A. Under these conditions, the Van 

 der Waals attraction may begin to lessen on account of the fact 

 that the additive feature of the intermolecular forces may cease 



