PRNP and Creutzfeldt Jacob disease: The prion transmission pattern for transgenic line Tg49 that had a lower level of expression of human PrP 200K, also followed a similar trend, being characterized by high clinical attack rates and almost identical incubation periods of 344 days for iatrogenic CJD inoculum I026, and 348 days for IPD E200K-129MM inoculum I1091 (Table 5).