34. THE RIBONUCLEIC ACIDS OF VIRUSES 301 



of alkaline and acid hydrolysis of treated nucleic acid showed no differences 

 from those of untreated nucleic acid. The fact that hydroxylamine can 

 inactivate free RNA from animal viruses as well as from TMV, 104 but does 

 not attack all RNA-containing viruses, suggests that this agent attacks a 

 special configuration in the nucleic acid component of certain viruses since 

 it appears that all nucleic acids have certain chemical properties, such as 

 types of bases and phosphoester backbone, in common. Franklin and 

 Wecker 182 concluded that this configuration could be an amino acyl ester 

 or some other acyl group in an ester linkage, located at a terminal position 

 on the high molecular weight RNA chain as is the case with the low molecu- 

 lar weight soluble RNA from liver cells. They based their assumption on the 

 similarity between the stability of infectious RNA and the amino acyl ester 

 bond of the soluble RNA at different pH values, as well as on similarities in 

 behavior with hydroxylamine and hydrazine. Neither hydrazine nor semi- 

 carbazide caused an inactivation of infectious RNA from ME virus. A more 

 direct approach to this problem is difficult because the direct determination 

 of probably one amino acyl group in one molecule of RNA seems to be 

 impossible. 



b. Reaction with Nitrous Acid 



The ribonucleic acid of mouse encephalomyelitis virus can be inactivated 

 by nitrous acid as was the case for TMV and its nucleic acid. 183 Since it is 

 still quite difficult to obtain large amounts of infectious RNA from animal 

 viruses, and since the biological test for infectious RNA from animal viruses 

 is not yet completely satisfactory, kinetics of inactivation with HNO2 were 

 studied in more detail with intact viruses. All viruses which have been 

 tested up to date were inactivated with nitrous acid. Among these viruses 

 are poliomyelitis virus, mouse encephalomyelitis virus, Newcastle disease 

 virus, and influenza virus. The reaction kinetics showed that all viruses 

 studied are inactivated more rapidly than the free RNA from TMV. 102 In 

 the case of poliovirus and influenza virus, the RNA content per virus 

 particle is the same as that per TMV particle. Furthermore, it is unlikely 

 that the amino bases in RNA from different sources react differently with 

 nitrous acid. Thus, the more rapid inactivation of animal viruses may be 

 due to an alteration of other viral components by HN0 2 . 



Acknowledgment 



The author is much indebted to Dr. R. M. Franklin for the translation of the 

 manuscript. 



183 W. Schafer, H. Schuster, T. Zimmermann, and R. Rott, Z. Natitrforsch. 14b, 632 

 (1959). 



