title: Effect of mouse peritoneal macrophages on scrapie infectivity during extended in vitro incubation.
abstract: Mouse peritoneal macrophages were exposed to scrapie (ME7 strain) brain homogenate in vitro for 2 h at 37 degrees. The samples were assayed for infectivity by analysis of scrapie incubation periods and their values compared to those obtained after extended (1-28 days) in vitro incubation. The scrapie incubation periods for scrapie agent-macrophage mixtures which had undergone extended in vitro incubation were longer than for mixtures assayed after a 2-hour exposure to the scrapie agent. The difference in scrapie incubation periods was more dramatic when residual scrapie was eliminated by washing the cells after the 2-hour exposure to brain homogenate. The scrapie incubation period also increased following in vitro incubation of ME7 in the absence of cells; however, the changes were less than those observed for scrapie agent-macrophage mixtures. In a culture in which cells had been destroyed by UV irradiation after exposure to the scrapie agent, there was more scrapie infectivity than in a comparable culture of untreated, scrapie-exposed macrophages. These results show that scrapie infectivity decreases with extended incubation of scrapie-exposed macrophages, and the data suggest that macrophages can inactivate the scrapie agent in vitro.
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005260:Female; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL / Q000276:immunology; D010587:Phagocytosis; D011328:Prions / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D013997:Time Factors; D014775:Virus Activation
chemical_list: D011328:Prions