The absence of any visible lymphoreticular system (LRS) involvement in the experimentally challenged animals is consistent with what has been observed in natural cases of atypical scrapie [13] and cannot be attributed to the experimental route of exposure, since the classical scrapie controls challenged by the same route had widespread labelling of disease-associated PrP (PrPSc) in the lymphoid tissues. The gene discussed is PRNP; the disease is scrapie.