Related Experiment Videos
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.
Insights
Mouse macrophages exposed to scrapie agent showed reduced infectivity over time. These findings suggest that macrophages can inactivate the scrapie agent in vitro, offering insights into prion disease mechanisms.
Area of Science:
- Neuroscience
- Immunology
- Infectious Diseases
Background:
- Scrapie is a transmissible spongiform encephalopathy (TSE) affecting sheep and goats.
- Macrophages play a role in the immune response and prion disease pathogenesis.
- Understanding prion inactivation mechanisms is crucial for disease control.
Purpose of the Study:
- To investigate the effect of extended in vitro incubation on scrapie infectivity in mouse peritoneal macrophages.
- To determine if macrophages can inactivate the scrapie agent.
Main Methods:
- Mouse peritoneal macrophages were exposed to scrapie (ME7 strain) brain homogenate in vitro.
- Infectivity was assayed by measuring scrapie incubation periods after varying incubation times (2 hours to 28 days).
- Macrophages were washed to remove residual agent, and UV irradiation was used to assess cell viability's role.
Main Results:
- Extended in vitro incubation of scrapie agent-macrophage mixtures led to longer scrapie incubation periods.
- This reduction in infectivity was more pronounced after washing cells to remove residual agent.
- In vitro incubation of scrapie alone showed less inactivation compared to macrophage-associated cultures.
- UV-treated macrophages retained more scrapie infectivity than untreated macrophages, indicating a cell-dependent inactivation process.
Conclusions:
- Extended incubation with macrophages significantly decreases scrapie infectivity in vitro.
- Macrophages possess the capacity to inactivate the scrapie agent.
- These findings highlight a potential host-mediated mechanism for prion clearance.