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Scrapie in vitro: agent replication and reduced cell yield
Abstract:
Exposure of PAM cells, a spontaneously transformed mouse cell line, to brain homogenates from mice infected with scrapie caused a relative decrease in total cell yield, which persisted from passage 2 or 3 to passage 18 after treatment. The effect was elicited by each of the eight independent scrapie isolates tested. Lysates prepared from cultures 16 passages after treatment with scrapie caused the decrease when applied to fresh PAM cultures. Mice inoculated with passage 14 and 18 lysates developed a reduced percentage of polymorphonuclear neutrophils by 5 weeks and scrapie disease by 6 to 9 months after inoculation. Based on the total dilution from treatment of the PAM cultures with scrapie material to the preparation of the lysates, we conclude that the agent(s) responsible for the reduced PAM cell yield, the decreased percentage of polymorphonuclear neutrophils, and the induction of scrapie disease had replicated in the PAM cells. By filtration, the diameter of the agent causing the reduction in cell yield was estimated to be between 25 and 50 nm.
Insights
Scrapie infection in mice brain homogenates reduced mouse cell yield and altered immune cell percentages. The infectious agent replicated in cultured cells, causing scrapie disease and indicating a transmissible spongiform encephalopathy agent.
Area of Science:
- Neuroscience
- Infectious Diseases
- Cell Biology
Background:
- Scrapie is a transmissible spongiform encephalopathy affecting mice.
- Understanding the replication and effects of the scrapie agent is crucial for disease research.
Purpose of the Study:
- To investigate the effects of scrapie infection on mouse cell cultures.
- To determine if the scrapie agent replicates in cultured cells and retains infectivity.
Main Methods:
- Exposure of PAM cells to scrapie-infected mouse brain homogenates.
- Assessing cell yield and immune cell profiles in treated mice.
- Filtration to estimate the size of the infectious agent.
Main Results:
- Scrapie exposure reduced PAM cell yield from passage 2/3 to 18.
- Lysates from treated cells induced similar effects in fresh cultures.
- Mice inoculated with lysates showed reduced neutrophils and developed scrapie disease.
- The infectious agent was estimated to be 25-50 nm in diameter.
Conclusions:
- The scrapie agent replicated in PAM cells, retaining its ability to induce disease.
- PAM cells provide a model for studying scrapie agent replication and pathogenesis.
- The study confirms the transmissible nature of the scrapie agent and its biological effects.