412 S. GARD AND O. MAAL0E 



being volatile and apparently leaving the media intact. Applied in concen- 

 trations of 1 to 2 % it inactivates 10^-10^ ID50 of influenza A and B, NDV, 

 Theiler's, and EMC viruses in 60 minutes at + 4°C., followed by 24 hours at 

 37°C. (Ginsberg and Wilson, 1950; LoGrippo and Rupe, 1957). The kinetics 

 of inactivation do not seem to have been studied. LoGrippo and Rupe (1957) 

 also found that diepoxybutane and butylene oxide inactivate the EMC and 

 EEE viruses, as did several ethyleneimines. 



Betapropiolactone (BPL) is a versatile substance insofar as the lactone 

 ring may open at either the alkyl or acyl oxygen bond; thus, both alkylation 

 and acylation may be achieved. On hydrolysis, beta-substituted propionic 

 acids and readily polymerizing hydracryhc acid are formed. For a discussion 

 of the chemistry of BPL and for further references the reader is referred to 

 KeUy et al. (1957). The half-hfe of BPL at 37°C. is about 30 minutes. Thus, 

 hydrolysis proceeds at a sufiiciently slow rate to permit kinetic studies and 

 make reproducibihty of experimental conditions feasible. BPL was found to 

 inactivate aU viruses so far tested. Data on the kinetics of inactivation are 

 still scarce; in studies by LoGrippo and Rupe (1957) and Hartman and 

 LoGrippo (1957) a "tailing effect" was described, i.e., the final level of sur- 

 vival was not a linear function of the concentration of the drug. This fact 

 indicates that also in this case membrane effects interfere with the penetra- 

 tion of BPL into the interior of the virus particle. 



F. Organic Solvents 



The group of organic solvents is rather heterogeneous, not only chemically, 

 but also with regard to the mechanisms of action. Almost aU agents to be 

 discussed in this section denature jDroteins, particularly at elevated tempera- 

 tures. Some of them, under carefuUy controlled conditions, precipitate pro- 

 teins in the native state. The solvent character is of interest mainly in the 

 specifically lipid solvents. 



The short-chain ahphatic alcohols precipitate viruses from aqueous solu- 

 tions. Applied in the cold they leave infectivity virtually intact. For that 

 reason methanol and ethanol have been used for purification purposes 

 (Cox et al, 1947; Pollard et al, 1949; Moyer et al, 1950; Schwerdt and 

 Schaffer, 1956). At elevated temperatures denaturation and inactivation 

 occur. Higher alcohols of low solubihty can be used for deproteinization of 

 crude virus suspensions without demonstrable inactivation. Bachrach and 

 Schwerdt (1952) apphed butanol for this purpose in purification of poHo- 

 virus. 



Glycols are apparently somewhat less active as denaturing agents. They 

 have been used in aerosol form for disinfection purposes and, in this connec- 

 tion, were also tested for their capacity to inactivate air-borne viruses 



