Effect of beta-propiolactone, ultraviolet irradiation, and formalin on Sendai virus cell-fusion factor

Summary Beta-propiolactone (BPL) treatment of Sendai virus 20 × concentrate was the only method which completely destroyed virus infectivity leaving the cell-fusion factor essentially unaffected. Under conditions used in this study, formalin treatment resulted in residual infectivity and almost completely destroyed the fusion factor. Ultraviolet irradiation had no appreciable effect upon the fusion factor, however, residual infectivity was considerable. Storage for 6 months at -70°C in phosphate-bufferedsaline containing 0.5% bovine plasma albumin did not seem to affect Sendai virus hemagglutinin and infectivity. Although the fusion factor titer as measured by titration endpoints appeared unaffected by storage, the fusion in individual tube cultures caused by preparations stored for 6 months appeared less extensive than that seen after less storage.