根據(jù)一份今天提出的報(bào)告,，醫(yī)學(xué)界已研發(fā)出預(yù)防小鼠罹患狂牛癥等嚴(yán)重腦部疾病的口服疫苗,。這種疫苗可以防止感染致命蛋白質(zhì)prion，而這種有毒蛋白質(zhì)會(huì)藉由改變正常細(xì)胞的prion蛋白質(zhì)，引發(fā)腦部受損,。
因?yàn)檫@種有毒蛋白質(zhì)與正常prion蛋白質(zhì)過(guò)于類似,，免疫系統(tǒng)無(wú)法消滅它們，受到感染的動(dòng)物與人的腦部受到無(wú)法復(fù)原的損害,，會(huì)出現(xiàn)癡呆與肢體異?；顒?dòng)癥狀。
研究人員將這種prion有毒蛋白質(zhì)附加在一個(gè)經(jīng)過(guò)基因改造的沙門(mén)氏菌菌株上,，讓免疫系統(tǒng)找出并消滅這種具有傳染性的有毒蛋白,。他們發(fā)現(xiàn)，血液內(nèi)抗體量較高的小鼠,，經(jīng)過(guò)四百天后仍無(wú)疾病癥狀,，抗體量低的小鼠發(fā)病時(shí)間也延后了。
小鼠通常需要一百二十天,，才會(huì)罹患這種prion蛋白疾病,。紐約大學(xué)醫(yī)學(xué)院的Thomas Wisniewski表示，這些發(fā)現(xiàn)可說(shuō)是大有可為的,。研究人員目前正在重新設(shè)計(jì)疫苗,，使疫苗可以使用在鹿與牛身上。但是要將疫苗使用在人類身上,，還須經(jīng)過(guò)許多研究工作,。但是廣泛為動(dòng)物施打疫苗，可以保護(hù)人類,。
（姜欣慧譯）
英文原文：
Vaccine Prevents Prion Disease In Mice
biocompare,，5/3/2007
Source: American Academy of Neurology
An oral vaccine can prevent mice from developing a brain disease similar to mad cow disease, according to research that will be presented at the American Academy of Neurology's 59th Annual Meeting in Boston, April 28 – May 5, 2007. Prion diseases, which include scrapie, mad cow disease, and chronic wasting disease, are fatal and there is no treatment or cure.
The disease spreads when an animal eats the body parts of other animals contaminated with prions. The disease causes dementia and abnormal limb movements.
Prion is a protein that is also an infectious agent. The proteins are so similar to proteins found normally that the immune system does not fight them off. To develop a vaccine that would stimulate the mice's immune system, researchers attached prion proteins to a genetically modified strain of Salmonella.
For the study, the mice were orally vaccinated with a safe, attenuated Salmonella strain, which expressed the prion protein. Then they were divided into two groups – those who had high levels of antibodies in their blood and thus responded well to the vaccine and those with low levels of antibodies.
The mice with high levels of antibodies had no symptoms of the disease after 400 days. The mice with low levels of antibodies also had a significant delay in the onset of the disease. It normally takes 120 days for mice that have not been vaccinated to develop the disease.
"These are promising findings," said study author Thomas Wisniewski, MD, of NYU School of Medicine in New York, and a member of the American Academy of Neurology. "We are now in the process of redesigning the vaccine so it can be used on deer and cattle."
Wisniewski said much more work is needed before the vaccine could be considered for humans. "The human version of prion disease usually occurs spontaneously and only rarely because of eating contaminated meat," he said. "But if, for example, a more significant outbreak of chronic wasting disease in deer and elk occurs and if it were transmissible to humans, then we would need a vaccine like this to protect people in hunting areas."
He also noted that a vaccine that decreases the spread of prion disease in animals also reduces the possibility that the disease could infect humans.
