Comparative effects of beta-propiolactone on mice, mouse-derived cell cultures, and Venezuelan equine encephalomyelitis virus

Studies were made comparing the toxicity of beta-propiolactone (BPL) for mammalian (mouse) cells in vitro and for mice and for Venezuelan equine encephalomyelitis (VEE) virus which is highly cytopathogenic for each. The mammalian cells grown in tissue culture were found to be adversely affected by BPL in concentrations ranging from 0.001 to 0.1 mg/ml of supernatant fluid. The difference in response was influenced by the menstruum in which the BPL was suspended and the difference in cell types tested. Tenfold less BPL appeared to be required to destroy the cells when it was suspended in a balanced salt solution than when it was suspended in protein-containing solutions such as beef heart infusion broth or medium 199 plus 20% horse serum. Secondary embryonic mouse lung cells seemed slightly more adversely affected by BPL than the established embryonic lung or L cells. BPL given to mice by intranasal instillation and by intracerebral injection was lethal to half of the animals within 2 days at doses of 0.31 and 0.39 mg, respectively. Higher concentrations of BPL were required to rapidly inactivate the virus in vitro than were required to kill mice or to cause a toxic effect on cells in culture. It required 10 mg/ml of BPL to completely inactivate a high-titered VEE virus preparation in 5 min and 1 mg/ml to inactivate most, but not all, of the virus in 15 min. A concentration of 0.1 mg/ml of BPL had only a slight effect on the virus after a period as long as 60 min. Evidence is presented indicating that simultaneous inactivation of all of the properties of the VEE virus particles by BPL aerosols did not occur at the same time but that, after treatment, the virus possessed a limited ability to immunize mice despite a loss in infectivity.

An evaluation of beta-propiolactone for the sterilization of fermentation media

Twenty-five bacterial species were cultured in basal broth plus 1 of 19 different carbohydrates which were sterilized by Seitz filtration, autoclaving (112 C, 10 min), or exposure to 0.2% beta-propiolactone (BPL). No significant differences were found either in the visual observations for acid and gas, pH, or titrable acidity determinations after 3 days of incubation with any of the three preparations tested. An effort was made to further determine the effect of BPL and heat on carbohydrates by assaying for glucose before and after treatment. Results indicated that glucose was not degraded by 0.2% BPL, however, it was shown that autoclave temperatures caused extensive degradation. Statistical treatment of the results from Warburg studies indicated that BPL-treated glucose showed no appreciable toxic effects, although the actual oxygen uptake was not as great as with Seitz- or autoclave-treated glucose. The application of the BPL sterilization process was discussed.