Comparison study on clinical and neuropathological characteristics of hamsters inoculated with scrapie strain 263K in different challenging pathways.
OBJECTIVE
To understand the infectious characteristics of a hamster-adapted scrapie strain 263K with five different routes of infection including intracerebral (i.c.), intraperitoneal (i.p.), intragastrical (i.g.), intracardiac and intramuscular (i.m.) approaches.


METHODS
Hamsters were infected with crude- or fine-prepared brain extracts. The neuropathological changes, PrP(Sc) deposits, and patterns of PK-resistant PrP were analyzed by HE stain, immnunohistochemistry (IHC) assay and Western blot. Reactive gliosis and neuron loss were evaluated by glial fibrillary acidic protein (GFAP) and neuron specific enolase (NSE) specific IHC.


RESULTS
The animals inoculated in i.m. and i.p. ways with crude PrP(Sc) extracts showed clinical signs at the average incubation of 69.2 +/- 2.8 and 65.5 +/- 3.9 days. Inoculation in i.c. and intracardiac ways with fine PrP(Sc) extracts (0.00035 g) caused similar, but relative long incubation of around 90 days. Only one out of eight hamsters challenged in i.g. way with low dosage (0.01 g) became ill after a much longer incubation (185 d), while all animals (4/4) with high dosage (0.04 g) developed clinical signs 105 days postinfection. The most remarkable spongiform degeneration and PrP(Sc) deposits were found in brain stem among the five challenge groups generally. The number of GFAP-positive astrocytes increased distinctly in brain stems in all infection groups, while the number of NSE-positive cells decreased significantly in cerebrum, except i.c. group. The patterns of PK-resistant PrP in brains were basically identical among the five infection routes.


CONCLUSIONS
Typical TSE could be induced in hamsters by inoculating strain 263K in the five infection ways. The incubation periods in bioassays depend on infective dosage, administrating pathway and preparation of PrP(Sc). The neuropathological changes and PrP(Sc) deposits seem to be related with regions and inoculating pathways.
Zhang
Jin
J
National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Yingxin Rd. 100, Beijing 100052, China.
Chen
Lan
L
Zhang
Bao-Yun
BY
Han
Jun
J
Xiao
Xin-Li
XL
Tian
Hai-Yan
HY
Li
Bin-Ling
BL
Gao
Chen
C
Gao
Jian-Mei
JM
Zhou
Xiao-Bo
XB
Ma
Gui-Ping
GP
Liu
Yong
Y
Xu
Cai-Min
CM
Dong
Xiao-Ping
XP
D000284:Administration, Oral; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D006224:Cricetinae; D005911:Gliosis / Q000378:metabolism / Q000473:pathology; D007150:Immunohistochemistry; D007273:Injections, Intramuscular; D007274:Injections, Intraperitoneal; D007276:Injections, Intraventricular; D009474:Neurons / Q000201:enzymology / Q000473:pathology; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D011328:Prions / Q000008:administration & dosage / Q000378:metabolism / Q000472:pathogenicity; D012608:Scrapie / Q000378:metabolism / Q000473:pathology*
D011328:Prions; D010751:Phosphopyruvate Hydratase