%0 Journal Article %A Dees, C. %A Wade, W. F. %A German, T. L. %A Marsh, R. F. %T Inactivation of the Scrapie Agent by Ultraviolet Irradiation in the Presence of Chlorpromazine %D 1985 %J Journal of General Virology, %V 66 %N 4 %P 845-849 %@ 1465-2099 %R https://doi.org/10.1099/0022-1317-66-4-845 %K lipid %K scrapie %K nucleic acid %K phenthiazine antipsychotics %K irradiation %I Microbiology Society, %X SUMMARY The sensitivity of the scrapie agent to u.v. inactivation was found to be related to the purity of the tissue preparation. Scrapie infectivity associated with membrane vesicles was unaffected when irradiated with 104 J/m2. Irradiation of more highly purified preparations from detergent-extracted CsCl gradient fractions reduced scrapie infectivity from 107.8 log10 LD50 per ml to as low as 104.5. Sensitivity of membrane-associated scrapie infectivity to inactivation by u.v. irradiation could be increased by addition of chlorpromazine, a phenthiazine antipsychotic which penetrates lipid bilayers and induces single-strand breaks in nucleic acids under irradiation. Chlorpromazine without irradiation, and a semiquinone protein-binding radical of chlorpromazine, failed to decrease scrapie infectivity by themseleves. A closely related phenthiazine antipsychotic, trifluoperazine, which does not bind to nucleic acids, did not reduce scrapie infectivity. These findings suggest that the target of u.v. radiation for inactivation of scrapie infectivity in the presence of chlorpromazine is an essential nucleic acid. %U https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-66-4-845