Prion protein immunohistochemical staining in the brains of monkeys with transmissible spongiform encephalopathy

Prion protein (PrP) immunohistochemical staining of the brains of common ma rmosets (Callithrix jacchus) with experimental transmissible spongiform enc ephalopathy is described. The monkeys (n = 17) had been injected, intracere brally, 17-49 months previously with homogenates of brain tissue taken post mortem from a cow with BSE (n = 2 monkeys), a sheep with natural scrapie ( n = 2 monkeys), human cases of growth hormone related Creutzfeldt-Jakob dis ease (CJD) (n = 2 monkeys), sporadic CJD (n = 5 monkeys), or Gerstmann-Stra ussler-Scheinker disease (GSS) (n = 4 monkeys), or from monkeys with spongi form encephalopathy resulting from injection with brain tissue from these l ast two cases (n = 1 monkey from each case), Only diffuse PrP-staining was seen in monkeys injected with CTD-material whereas more aggregated deposits of PrP were seen in monkeys injected with BSE-, scrapie-and GSS-brain tiss ue, There were no patterns of staining specific to the brains injected with BSE-material that could be used to identify the origin of that inoculum. B SE-and scrapie-injected monkey brains could be distinguished from each othe r because in BSE-injected monkey brain the spongiform vacuolation was large ly confined to subcortical structures whereas in scrapie-injected monkey br ain the spongiform vacuolation was also prominent in the neocortex, The pat terns of PrP deposition differed markedly between those seen in monkey brai ns injected with BSE-material or CJD-material, but the patterns of PrP stai ning seen in monkey brains injected with BSE-material were also seen in mon key brains injected with scrapie-or GSS-material. Overall there was a corre lation between the length of the incubation period and the amount of aggreg ated PrP-staining, but no correlation between the neuropathological picture and the clinical presentation of neurological signs.