Sheep major histocompatibility (OLA) complex: linkage between a scrapie susceptibility/resistance locus and the OLA complex in Ile-de-France sheep progenies.

As seen on their family trees, Ile-de-France sheep with scrapie show genetic susceptibility to this disease, which is transmitted via scrs, an autosomal recessive gene. Scrapie occurred in homozygous recessive sheep, whereas the presence of the dominant resistance allele Scrr sufficed to prevent this disease in heterozygous animals. This hypothesis, previously proposed by Parry (1962), was tested in a study involving 133 crossings of sheep of different genotypes, and verified in the observed progenies.

In vitro propagation of the scrapie agent. I. Transformation of mouse glia and neuroblastoma cells after infection with the mouse-adapted scrapie strain c-506.

Seven cell lines including glia cells from mouse brains and mouse neuroblastoma cells were infected with the mouse-adapted scrapie strain c-506. During the early in vitro passages, a stimulation of growth was already observed but cellular morphology and differentiation did not alter. Later on, after 12-16 passages, six of the seven infected lines displayed cell proliferation and morphological alterations, suggesting an in vitro morphological transformation.