Enucleation after intraocular scrapie injection delays the spread of infection.

After right intraocular infection, mice develop lesions in the contralateral retinal projections long before clinical disease occurs. Enucleation up to 7 days post-infection prevented targeting of lesions to visual projections, and prolonged the incubation period. When enucleation was delayed until at least 14 days post-infection, lesion targeting and incubation periods were similar to unenucleated mice. It was concluded that infectivity took a minimum of 14 days to reach the brain via the optic nerve.

Retrograde transneuronal transport of herpes simplex virus in the retina after injection in the superior colliculus, hypothalamus and optic chiasm.

Immunocytochemistry was used to identify infected cells after injection of Herpes simplex virus (HSV) into the superior colliculus, hypothalamus and optic chiasm. Ganglion cells of the retina were labeled in a pattern consistent with known projections to retinorecipient nuclei. Cells of both the inner and outer nuclear layer were labeled. If this represents retrograde transneuronal transport, then HSV may provide an important tool for studying the neuronal circuitry of the retina.

Targeting of scrapie lesions and spread of agent via the retino-tectal projection.

Scrapie infectivity and degenerative vacuolation was initially localized within the contralateral superior colliculus following intraocular injection. The time course of these events was prolonged. With the ME7 strain of scrapie in Sincs7 genotype mice, infectivity began to rise in the superior colliculus from about 70 days, followed by the earliest asymmetrical lesions there from 120 days, with death occurring at about 250 days, at which time vacuolar degeneration was widespread in the brain. With other mouse Sinc genotype mouse/agent strain combinations the process was even further prolonged. With 87V scrapie strain in Sincp7 genotype mice the first lesions to appear were in the contralateral tectum at 300 days. It is concluded that scrapie agent can spread within ganglion cell axons.