The fate of ME7 scrapie infection in rats, guinea-pigs and rabbits.

The fate of an intracerebral injection of ME7 scrapie has been followed in groups of rats, guinea-pigs and rabbits. Six days after injection scrapie activity in the brain was similar in all three species and low levels of activity were also present in rat and guinea-pig spleen. Thereafter in the rat the pattern of accumulation of scrapie agent in brain and spleen resembled that frequently described in mice, the disease becoming clinically manifest 20 months after injection. In guinea-pig and rabbit attempts to demonstrate scrapie agent at later stages of lifespan were generally unsuccessful. It is tentatively concluded that in these last two species replication of scrapie agent did not occur though in the guinea-pig there was some evidence that infection could persist for several months. An alternative explanation of the results is briefly discussed.