Fig 5. Illustration of breakdown during the transmission of L-type prions in mice and effective amplification in GT1-7 cells.
Grey mice and cells indicate the presence of L-type prions, while white mice and cells indicate S-type prions. Mice exhibiting the L-type disease still harbor S-type scrapie prions, resulting in the appearance of mice with the S-type disease at every passage from P2 to P4. GT1-7 cells accumulate PrPSc in response to L-type prions and can be used to re-propagate mice with L-type prions by injecting mice with cell homogenates. In contrast, GT1-7 cells challenged with S-type prions do not accumulate PrPSc, but they do harbor very low levels of S-type prion infectivity.