Detection of beef contaminated by bovine central nervous system tissue by enzyme immunoassay / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To study influencing factors of detection of bovine central nervous system (CNS) tissue contaminated beef by enzyme immunoassay (EIA), and the method was applied to the detection of imported beef and domestic beef of China.</p><p><b>METHODS</b>Raw beef homogenates containing different concentrations of raw CNS tissue and the same samples which were heated were detected after different time by RIDASCREEN(r) Risk Material 10/5 and RIDASCREEN(r) Probennahme- zubehor Sampling tools kits. PBS suspension and sample dilution buffer (SDB) suspension of bovine brain tissue with the same concentration of the standard were detected. Beef from USA and domestic market of China were then detected by the kits.</p><p><b>RESULTS</b>The kits could detect both raw and heated CNS tissue in the products with high sensitivity. The absorbance values (AV) increased with the concentrations of CNS in samples. Heating and increasing of time could decrease the absorbance values of the samples which contain CNS tissue. The AV of the PBS suspension of bovine brain tissue was higher than the SDB suspension and the AV of both were higher than the AV of standard of the same concentration. No CNS tissue was detected from all imported beef. No CNS tissue was detected in all samples from domestic market of China except for foxtail.</p><p><b>CONCLUSION</b>The EIA method has high sensitivity for detection of bovine CNS tissue contaminated beef with the glial fibrillary acidic protein (GFAP) as accurate target substance. Heating and increasing of time can lead to decreasing of the AV of samples. Improper slaughter process can lead to contamination of bovine products by bovine CNS tissue.</p>

Comparison study on clinical and neuropathological characteristics of hamsters inoculated with scrapie strain 263K in different challenging pathways / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>