300 HEINZ SCHUSTER 



RNA from different viruses should have approximately the same density. 

 (2) The different nucleic acids must have a basic structure similar to that 

 of TMV-RNA. Similarities in molecular size and structure between TMV- 

 RNA and an RNA component from plant and animal tissues have recently 

 been demonstrated. 180 On the other hand, there have not yet been any 

 comparative studies between nucleic acids from different viruses. If the 

 above mentioned equation is used to calculate the molecular weight of the 

 virus RNA specimens which have been studied, the molecular weight of 

 RNA from West Nile, Mengo, and poliomyelitis virus is about 2 X 10 6 , 

 and that from foot and mouth disease is about 3 X 10 6 . Hence, it seems 

 likely that, also, in case of RNA from animal viruses, only a high molecular 

 weight component possesses the ability to induce infection. 



5. Reaction of Infectious Ribonucleic Acids with Chemical Agents 



The reaction of infectious RNA of animal viruses with chemical agents 

 has only been studied in detail for hydroxy lamine and nitrous acid. Chemi- 

 cal methods have not yet been employed to characterize this type of RNA 

 in more detail. 



a. Reaction with Hydroxy lamine 



Certain bacterial viruses can be inactivated with hydroxylamine and in 

 this case the inactivation seems to be due to alteration of virus protein, 

 probably by splitting thiolester bonds. 181 A series of animal RNA viruses 

 have been inactivated with hydroxylamine, and among these are mouse 

 encephalomyelitis virus, WEE virus, fowl plaque virus, and swine in- 

 fluenza. 182 Other RNA-containing viruses, such as NDV and mumps virus, 

 are resistant to this compound. Infectious RNA from ME virus is in- 

 activated by hydroxylamine at a rate comparable to that of the virus itself. 

 Thus, it appears likely that hydroxylamine inactivates the ME virus by 

 reacting with the RNA component rather than with the protein. This is 

 supported by the fact that certain properties of virus protein are not in- 

 fluenced by hydroxylamine inactivation. Among such properties which 

 have been tested are serological properties of ME virus, serological prop- 

 erties of fowl plague virus, as well as enzymic activity and hemagglutinating 

 activity of fowl plague virus. 



The nature of the reaction of hydroxylamine with RNA is not yet known. 

 Model experiments were made using high molecular weight RNA from 

 various sources and these showed that hydroxylamine apparently does not 

 split the phosphoester linkages of the RNA backbone. Further, the products 



180 A. Gierer, Z. Naturforsch. 13b, 788 (1958). 



181 L. M. Kozloff, M. Lute, and K. Henderson, J. Biol. Chem. 228, 511 (1957). 



182 R. M. Franklin and E. Wecker, Nature. 184, 343 (1959). 



