PRNP and prion disease: Further, in prion diseases, infection with prions (PrPSc) may cause a gut dysbiosis which produces microbial amyloid that activates the immune system, triggers misfolding and aggregation of prion protein PrPC in the brain, conforms normal PrPC to pathological prions (PrPSc), activates microglia, and enhances neuronal amyloid production and accumulation (136).