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Vaccine Aims at Fly Host of Disease Parasite
新型疫苗直接对付寄生虫的宿主
Leishmaniasis is a sometimes fatal disease marked by skin ulcers, fever, and spleen and liver problems. It currently affects about 12 million people, mostly in the developing world, with about 2 million new infections annually. It’s caused by a parasite, which is spread by sand flies.
利什曼病有时候是致命的——其主要特征为皮肤溃疡、发烧以及脾脏和肝脏问题。目前大约有1200万人深受其害，大多患者集中在发展中国家。而且每年约有200万新的感染者。它由一种寄生虫引发，而这种寄生虫是由沙蝇传播的。
There is not yet a good vaccine against leishmaniasis. But researchers have shown that it may be worthwhile to target not the parasite—but its fly host. The report good results in non-human primates in the journal Science Translational Medicine.
目前还没有哪种疫苗能够很好的对抗利什曼病。但是研究人员表示，可以考虑不直接对付该寄身虫，而是去对付它的宿主——沙蝇。该研究在非人类灵长动物身上取得了良好效果。这项研究结果发表在《科学转化医学》杂志上。
Vaccines usually trigger our immune systems to rally against a pathogenic agent. If that agent should actually show up, the immune system can disarm it.
疫苗通常会触发我们的免疫系统去对抗病原体。如果病原体出现了，免疫系统就可以将其铲除。
But in this case, scientists aimed at the carrier—the sand fly. When an infected fly bites a victim, it injects parasites and its own saliva. So the researchers subjected monkeys to repeated bites from uninfected sand flies, then to bites from infected sandflies. And the monkeys bitten first by uninfected flies were partially protected when confronted with the leishmaniasis parasite. Seems that exposure to fly saliva alone could elicit an immune response.
但是针对这种疾病，科学家将目标锁定为该寄生虫的载体——沙蝇。当一个受到感染的沙蝇咬伤受害者时，它就会在受害者体内注入寄生虫以及它自己的唾液。因此，研究人员先让猴子多次被未受感染的沙蝇叮咬，然后再被受到感染的沙蝇叮咬。起初被未受感染的沙蝇叮咬过的猴子，在面对利什曼病寄生虫的时候获得了部分保护。由此可见，被未受寄生虫感染的沙蝇叮咬是可以引起免疫反应的。
The researchers then determined that one particular protein in the sand fly’s saliva kicked the immune system into action. A vaccine based on that protein offered partial protection, with 7 of 10 monkeys that got it developing smaller ulcers and a stronger immune response than their unvaccinated peers when infected with the parasite.
最终研究人员断定：沙蝇唾液中一种特定的蛋白质刺激免疫系统起了作用。一种以这一蛋白质为基础的疫苗似乎可以提供部分保护——在实验中，10个接种了这种疫苗的猴子里面有7个长出了较小的溃疡，并且与未接种疫苗的猴子相比，当感染了这种寄生虫时它们拥有更强的免疫反应。
This protein can be generated and purified easily from E. coli, which means that it’s possible to get large quantities of it to produce a potential future human vaccine against leishmaniasis. Which would make this saliva-based protection nothing to spit at.
大肠杆菌可以很容易地生成并净化这种蛋白质。这就意味着我们能够获得大量这种蛋白质，用以生产可对抗利什曼病的疫苗——一种有潜力在未来适用于人类的疫苗。而这将使这种以唾液为基础的蛋白质不再被蔑视。