Prion biology in transfusion medicine: implications for lab testing.

Although eerily silent for many years after the recognition of scrapie in 1759, TSEs remained present within the genome of some mammals. Not since the mid-1950s when Dr. Carleton Gadjusek visited the Fore Indians of New Guinea to study kuru, however, has there been a more frenetic interest by governmental investigators. Certainly, the U.K. experience has heralded a renewed interest in TSEs due to the notoriety associated with younger subjects succumbing to a variant CJD traced to the ingestion of beef. Human TSEs and the potential for their transmission among and across species of mammals has also captured the attention of many. Yet, to date, there is no reliable antemortem test available to screen for infected animals or humans. Antibody-based assays are difficult to develop because most of them do not have specificity for the pathogenic form of prion protein. Whether or not prion testing efforts will change dramatically depends upon the incidence of disease. Some speculate a reduction in testing, because BSE incidence is waning since the adoption of remedial steps in the U.K. in 1989. Others remind us, however, of the long latency of prion diseases and of the recent observations of two patients who succumbed to vCJD after having received blood products from donors who subsequently died of vCJD. The growing incidence of CWD, combined with the emerging observation that as many as 26% of Alzheimer's patients may have been misdiagnosed--having died instead of prion disease--maintains pressure for legislators to adhere to the precautionary principle and support blood-donor exclusionary criteria, antemortem-test development, and pathogen removal from donated blood. The laboratorian can expect to see new tests for prion disease work their way into clinical-testing practice in the near future. In addition, the adoption of newer filtration technologies holds the promise of improved protection from transfusion-transmitted prion disease.