PRNP and human prion disease: Similarly, when 101LL mice were inoculated with brain homogenate from sick GSS22 mice [53] (which overexpress 101L murine PrP and spontaneously develop neurological signs and large PrP amyloid plaques), no clinical signs of TSE disease or spongiform degeneration were evident, but large PrP amyloid plaques were again identified in the brains of these mice postmortem [55].