418 S. GARD AND O. MAAL0E 



Some protein-precipitating organic substances may also cause a reversible 

 reduction in infectivity. Thus, Vinson (1932) reported recovery of active 

 TMV from a noninfective safranine precipitate by treatment with amyl 

 alcohol, picric acid, or acetone; Krueger and Baldwin (1935) reactivated 

 safranine-treated bacteriophage by pH adjustment. Several tannic acids were 

 reported to inactivate bacteriophage (Fischer et at., 1954; Fischer, 1954); 

 Thornberry (1935), however, observed reactivation of tannic acid-treated 

 TMV after addition of gelatin or after filtration. 



During an earlier period the action of bile and bile salts upon viruses 

 attracted a certain interest. Recently Theiler (1957) emphasized the signifi- 

 cance of sensitivity to sodium deoxycholate (SDC) as a criterion in virus 

 classification. Systematic tests showed that SDC in a concentration of 1 : 1000, 

 applied for 1 hour at 37°C., caused inactivation of 3-5 log ID50 of all the 

 arthropod-borne (arbor) viruses of both subgroups A and B, of influenza A 

 and lymphocytic choriomeningitis (LCM) viruses, whereas polioviruses, 

 Theiler's GD VII and FA strains, Coxsackie, and EMC viruses remained 

 completely intact. It would thus seem that sensitivity to SDC and to ether 

 run largely parallel. This fact does not yet justify any conclusions as to the 

 mechanisms of inactivation. Generally speaking animal viruses can be 

 divided into two classes: stable and labile viruses. Those described as labile 

 are easily inactivated by heat, by acid pH, by lipid solvents, by enzymes, etc. 

 Several viruses of this category are known to contain Hpids. There are some 

 notable exceptions from the general rule, however. The hardy pohovirus is 

 abnormally sensitive to desiccation; the reportedly lipid-containing (54 %) 

 WEE virus is ether-resistant as well as remarkably thermostable (Beard,1945); 

 influenza virus is not attacked by proteolytic enzymes. These irregularities 

 at present appear somewhat puzzling; careful rechecking of the apparent in- 

 consistencies and studies of the SDC effect seem desirable. 



Some screening experiments, comprising large nmnbers of different chemi- 

 cals, have been reported (Stanley, 1935; Schultz and Robinson, 1942; LoGrippo 

 and Rupe, 1957). In general, relatively little specific information concerning 

 the structure of viruses or the mechanisms of inactivation can be extracted 

 from such reports. They will, therefore, not be reviewed in this coimection. 



References 



Ada, G. L. (1957). In "Tlie Nature of Viruses" (G. E. W. Wolstenholme and E. P. G. 



Millar, eds.), p. 104. Churchill, London. 

 Adams, M. H. (1948). J. Gen. Physiol. 31, 417. 

 Adams, M. H. (1949a). J. Gen. Physiol. 32, 579. 

 Adams, M. H. (1949b). J. Immunol. 62, 505. 

 Adams, M. H., and Lark, K. G. (1950). J. Immunol. 64, 335. 

 Adams, W. R., and Pollard, E. C. (1952). Arch. Biochem. Biophys. 36, 311. 



