朊病毒是一種只含有蛋白質(zhì)成分的病毒,，可引起羊瘙癢癥和瘋牛病等許多神經(jīng)性疾病,。
近日來(lái)自法國(guó)食品安全管理局的研究小組,，鑒定出朊病毒蛋白的一個(gè)新特性,，這一特性導(dǎo)致朊病毒能引起不同尋常的羊瘙癢病。這一研究論文8月29日發(fā)表在PLoS Pathogens上面,，這一研究結(jié)果將為阮病毒種間傳播的多樣性特征提供新的研究思路,。
朊病毒感染導(dǎo)致牛患海綿樣腦?。˙SE）的種群間傳播機(jī)制至今還未明確,，這種病毒還可通過牛肉食源性傳播路徑造成流行。典型的牛海綿樣腦病俗稱瘋牛病，經(jīng)食源傳播的朊病毒會(huì)導(dǎo)致人患克雅氏病,，對(duì)于克雅氏病暫無(wú)有效的治療手段,，通常導(dǎo)致人類產(chǎn)生退行性的神經(jīng)障礙癥狀?？茖W(xué)家們發(fā)現(xiàn)朊病毒的中間傳播機(jī)制可能與中間宿主有關(guān),，中間宿主包括羊，這些通常散發(fā)非典型的海綿樣腦病,，稱為L(zhǎng)-type BSE。
研究人員通過對(duì)朊病毒中一種具有抗蛋白酶活性的酶（protease-resistant prion protein ,，PrPres）分子結(jié)構(gòu)進(jìn)行分析,，發(fā)現(xiàn)引發(fā)羊瘙癢病與牛海綿樣腦病的朊病毒蛋白間的區(qū)別。研究者將三種朊病毒（引起牛海綿樣腦病的朊病毒,，L-type型牛海綿樣腦病朊病毒和羊瘙癢病朊病毒）分別感染轉(zhuǎn)基因小鼠,，結(jié)果轉(zhuǎn)基因小鼠的大腦過度表達(dá)羊瘙癢病朊病毒蛋白。從感染了上述三種朊病毒的小鼠腦內(nèi)抽取PrPres,。結(jié)果發(fā)現(xiàn),，感染羊瘙癢病骯蛋白的動(dòng)物發(fā)現(xiàn)有CH1641樣的病例， CH1641病例的PrPres與L-type BSE和典型BSE的PrPres酶具有相似的分子特征,。
在CH1641樣的羊瘙癢病例中,，阮病毒蛋白的分子結(jié)構(gòu)特征與L-type型接近，而與典型的BSE結(jié)構(gòu)有較大差異,。但是,，在4個(gè)CH1641羊瘙癢病例中，分離的朊病毒蛋白羧基端發(fā)生了病理性變化,，而在典型的BSE阮病毒蛋白和L-type阮病毒蛋白里沒有發(fā)現(xiàn)有類似的情況,，這就表明，羊瘙癢病朊病毒不是從BSE朊病毒演化而成,。（生物谷Bioon.com）
生物谷推薦原始出處：
PLoS Pathog 4(8): e1000137. doi:10.1371/journal.ppat.1000137
A C-Terminal Protease-Resistant Prion Fragment Distinguishes Ovine “CH1641-Like” Scrapie from Bovine Classical and L-Type BSE in Ovine Transgenic Mice
Thierry Baron*, Anna Bencsik, Johann Vulin, Anne-Ga?lle Biacabe, Eric Morignat, Jérémy Verchere, Dominique Betemps
Agence Franaise de Sécurité Sanitaire des Aliments–Lyon, Unité ATNC, Lyon, France
The protease-resistant prion protein (PrPres) of a few natural scrapie isolates identified in sheep, reminiscent of the experimental isolate CH1641 derived from a British natural scrapie case, showed partial molecular similarities to ovine bovine spongiform encephalopathy (BSE). Recent discovery of an atypical form of BSE in cattle, L-type BSE or BASE, suggests that also this form of BSE might have been transmitted to sheep. We studied by Western blot the molecular features of PrPres in four “CH1641-like” natural scrapie isolates after transmission in an ovine transgenic model (TgOvPrP4), to see if “CH1641-like” isolates might be linked to L-type BSE. We found less diglycosylated PrPres than in classical BSE, but similar glycoform proportions and apparent molecular masses of the usual PrPres form (PrPres #1) to L-type BSE. However, the “CH1641-like” isolates differed from both L-type and classical BSE by an abundant, C-terminally cleaved PrPres product (PrPres #2) specifically recognised by a C-terminal antibody (SAF84). Differential immunoprecipitation of PrPres #1 and PrPres #2 resulted in enrichment in PrPres #2, and demonstrated the presence of mono- and diglycosylated PrPres products. PrPres #2 could not be obtained from several experimental scrapie sources (SSBP1, 79A, Chandler, C506M3) in TgOvPrP4 mice, but was identified in the 87V scrapie strain and, in lower and variable proportions, in 5 of 5 natural scrapie isolates with different molecular features to CH1641. PrPres #2 identification provides an additional method for the molecular discrimination of prion strains, and demonstrates differences between “CH1641-like” ovine scrapie and bovine L-type BSE transmitted in an ovine transgenic mouse model.
