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Characterization of scrapie infection in mouse neuroblastoma cells
Abstract:
A mouse neuroblastoma cell line was successfully infected with scrapie agent. Agent derived from infected mouse brain or spleen infected cultures. However, agent from infected hamsters did not infect mouse cell cultures, suggesting that species specificity influenced the infection process in vitro. Positive cultures supported scrapie replication for as many as 47 passages in vitro. Agent was shown to be cell-associated and between 631 and 7943 unselected culture cells constituted 1 mouse LD50. However, fluctuation analysis indicated that only one of 144 cells in unselected cultures was actually infected. Thus, agent was confined to a small percentage of cells and only 4.4 to 55.1 positive cells were needed to confer a mouse LD50.
Insights
Mouse neuroblastoma cells can be infected with the scrapie agent in vitro, but species specificity affects infection. The agent replicates in cell cultures for extended passages, though it
Area of Science:
- Neuroscience
- Virology
- Cell Biology
Background:
- Scrapie is a transmissible spongiform encephalopathy affecting the central nervous system.
- In vitro models are crucial for studying prion diseases like scrapie.
- Understanding agent-host interactions in cell culture is vital for disease research.
Purpose of the Study:
- To establish and characterize an in vitro model of scrapie infection using a mouse neuroblastoma cell line.
- To investigate the species specificity of scrapie agent infection in cell cultures.
- To determine the efficiency of scrapie agent replication and cell association in vitro.
Main Methods:
- Infection of a mouse neuroblastoma cell line with scrapie agent from infected mouse brain and spleen.
- Exposure of cell cultures to scrapie agent derived from infected hamsters.
- Serial passage of infected cultures to assess agent replication.
- Quantification of infectious agent using lethal dose 50 (LD50) assays in mice.
- Fluctuation analysis to determine the proportion of infected cells.
Main Results:
- Successful infection of mouse neuroblastoma cells with scrapie agent from mouse sources.
- Demonstrated species specificity: hamster-derived scrapie agent did not infect mouse cells.
- Scrapie agent replicated in cell cultures for up to 47 passages.
- Scrapie agent was cell-associated, with a small percentage of cells harboring infectious particles.
- Between 4.4 and 55.1 infected cells were required to confer one mouse LD50.
Conclusions:
- Mouse neuroblastoma cell line serves as a viable in vitro model for scrapie infection.
- Species specificity plays a significant role in scrapie agent's ability to infect cells in vitro.
- Scrapie agent replication in vitro is sustained over multiple passages.
- The infectious agent is present in a limited fraction of the cell population, highlighting cellular heterogeneity in susceptibility.