Evidence for intrinsic control of scrapie pathogenesis in the murine visual system

Using the optic nerve to route scrapie infection into the brain reduces the initial spread of the disease to well-defined neuronal relays, and simplifies the observation of cause and effect of agent transport, replication and degeneration of the nervous system. One drawback of intraocular targeting of infection is the relatively long incubation periods required to produce clinical disease. By using highly-enriched fractions of infectivity and two models of murine scrapie, we have found that this time delay is not simply due to the limited amount of infective inoculum that can be injected into the eye. This provides evidence of intrinsic control of scrapie pathogenesis within the murine visual system.