296 HEINZ SCHUSTER 



the infectious material was 1.6-1.7, in good agreement with rather pure nucleic acid 

 preparations. The material contained no protein which could be detected either by 

 the biuret reaction or by acid hydrolysis followed by paper chromatography of 

 amino acids. 



A short incubation of the RNA preparations with ribonuclease or a longer incuba- 

 tion of 6 hours at 37°C. without enzymes destroyed the activity. Neither treatment 

 had any significant effect on the infectivities of the corresponding viruses. The in- 

 fectious material could be precipitated from 1 M NaCl solutions, whereas the virus 

 could not. When samples of virus and RNA preparations were centrifuged at 30,000 

 r.p.m. for 60 minutes — conditions under which virus but not viral RNA sedimented — 

 the infectivity was markedly reduced in the supernatants of virus preparations, 

 whereas that of RNA was but slightly affected. 



The infectivity of RNA from Mengo encephalitis virus was destroyed by treat- 

 ment with either Mengo antiserum (monkey) or normal monkey serum. On the other 

 hand, the infectivity of the virus was reduced only by specific antiserum. The loss of 

 infectivity, in this case, is probably due to the fact that the serum contains ribonu- 

 clease activity. 159 



b. RNA from Equine Encephalomyelitis Virus 165 - 166 



An infectious RNA component was isolated from the brains of mice infected with 

 equine encephalomyelitis virus of both eastern and western type (EEE virus, WEE 

 virus) after treatment with phenol. The infectivity could be tested in mice by 

 intracerebral injection of 0.03 ml. RNA or in embryonated eggs by injection of 0.2 

 ml. RNA in the allantois sac. Infectious material could be obtained, only, by adding 

 phenol to the tissues before homogenization. If the tissues were homogenized prior 

 to phenol extraction, the yield of RNA was significantly lower and the preparation 

 was not infectious. This loss in infectivity and the low yield is probably due to ribo- 

 nuclease activity. Since ribonuclease has little or no effect on the virus infectivity, 

 it is quite possible that the infectious component isolated by phenol treatment is 

 essentially free virus RNA or a precursor of this. 



This was supported by the fact that no infectious RNA could be isolated from a 

 purified concentrate of WEE virus by phenol treatment in the cold. After treatment 

 of this virus with hot phenol for 5 minutes at 40 or 50°C, the RNA could be extracted 

 in essentially quantitative yields, but the biological activity of this RNA was only 

 some 10~ 5 % of the original virus preparation. 167 



If bacteria are extracted with hot phenol, nucleic acid and lipopolysaccharides 

 are found in the aqueous phase 69 and, therefore, it may be that the lipid coat of 

 EEE virus, which has some 50% lipid, is only dissolved by treating with hot phenol. 

 All the preparations of infectious RNA were sensitive to ribonuclease and heat treat- 

 ment (4.5 hours, 37°C.) The activity could be precipitated with alcohol with no loss 

 in infectivity, whereas virus was inactivated by similar treatment. 



c. RNA from Poliomyelitis Virus 



Infectious RNA was extracted from the brains and spinal cords of hamsters which 

 had been infected 18-24 hours previously by intracerebral injection with a suspension 

 of type II MEFi strain of poliomyelitis virus. 164 The isolation and characterization 



165 E. Wecker and W. Schafer, Z. Naturforsch. 12b, 415 (1957). 



166 E. Wecker, Z. Naturforsch. 14b, 370 (1959). 



167 E. Wecker, Virology 7, 241 (1959). 



