title: Subclinical scrapie infection in a resistant species: persistence, replication, and adaptation of infectivity during four passages.
abstract: Cross-species infection with transmissible spongiform encephalopathy agents may lead to subclinical infection and to adaptation of the infection to new species. This is of particular concern for the millions of people possibly exposed to bovine spongiform encephalopathy (BSE) by consumption of BSE-infected beef. Subclinical infection was studied by making 4 serial passages of hamster scrapie agent (263K) in mice. At each step, infectivity was followed by inoculation of hamsters and mice. Subclinical infection was demonstrated either by detection of abnormal protease-resistant prion protein (PrP-res) or in the absence of PrP-res by detection of infectivity. Replication and adaptation of hamster infectivity in mice was shown in year 2 after initial mouse passage. In third and fourth passages, dual-tropic, mouse-tropic, and hamster-tropic infectivity was found in different animals. In some cases infectivity similar to the original 263K hamster scrapie strain was found after 2 or 3 serial mouse passages totaling 1200-1550 days.
authors.affiliation: Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, 903 S. Fourth Street, Hamilton, MT 59840, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Race
authors.forename: Kimberly
authors.initials: K
authors.lastname: Meade-White
authors.forename: Anne
authors.initials: A
authors.lastname: Raines
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Raymond
authors.forename: Byron
authors.initials: B
authors.lastname: Caughey
authors.forename: Bruce
authors.initials: B
authors.lastname: Chesebro
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001923:Brain Chemistry; D002353:Carrier State; D006224:Cricetinae; D010450:Endopeptidases / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018620:PrPSc Proteins / Q000032:analysis / Q000378:metabolism / Q000472:pathogenicity*; D012608:Scrapie / Q000503:physiopathology* / Q000821:virology; D012692:Serial Passage; D013045:Species Specificity
chemical_list: D018620:PrPSc Proteins; D010450:Endopeptidases