古代恐龙鸟类感染了乙肝-8200万年前乙肝病毒感染鸟类
Ancient Dinosaur Birds Were Infected With Hepatitis B
82 million years ago hepatitis B infected birds
上图：斑马雀是一种基因中含有古代乙肝痕迹的鸟类。(FurLined)
想知道所有现代雀、织工、乌鸦、松鸡、知更鸟和鸣禽的曾曾曾曾祖父母的伤心事吗?她携带着乙肝病毒的基因。如今，全世界每年约有62万人死于乙肝病毒。最近一项分析乙肝历史的研究发现，这种病毒至少在8200万年前就开始感染鸟类。
这只古老的鸟是所有现代雀形目和新鸟类的祖先，生活在中生代晚期，“那时恐龙还很活跃，”这位匿名博客作者写道。
据《科学新闻》报道，大约8200万年前，“一种乙肝病毒感染了一只古老的鸟类，并卡在了它的基因组中。“通常病毒进化得非常快。但是,一旦它的基因被困在古代鸟类的基因组,变化的速度GrrlScientist说病毒的基因“放缓的速度一样,宿主的DNA,”也就是说,科学家观察现代鸟类的基因可以看到相当于古代的乙型肝炎病毒的化石记录。科学新闻报道:
研究小组发现，重建的中生代病毒与今天感染人类的乙肝病毒非常相似。“我们经历了8200万年的进化，但它们拥有相同的蛋白质，”Suh说，他现在在瑞典乌普萨拉大学工作。
一个例外是一种叫X蛋白的臭名昭著的蛋白质。这种蛋白与肝癌的发生有关，是病毒在人类体内复制所必需的。由于感染现代鸟类的乙型肝炎病毒缺少X蛋白，许多科学家认为鸟类病毒在进化过程中失去了这种蛋白。但是这种古老的病毒也不含有X蛋白，这意味着鸟类可能从来没有过这种蛋白，X标记的哺乳动物乙肝病毒也是最近才发现的。
因此，研究人员认为鸟类首先感染了乙肝，然后才学会在哺乳动物中生存。在这项研究中，科学家们说了解这种病毒的历史可以帮助我们了解它是如何进化的。他们还说，这可能有助于“中生代肝病毒的体外复活”。但也许我们可以跳过这一部分。
Ancient Dinosaur Birds Were Infected With Hepatitis B
82 million years ago hepatitis B infected birds
Zebra Finches are one of the birds that hold a trace of ancient hepatitis B in their genes.
By Colin Schultz
SMITHSONIAN.COM
JULY 9, 2013
2202018
Want to know something sad about the great-great-great-great-…great-great-great grandparent of all modern finches, weavers, crows, jays, robins and all songbirds? She was carrying around the genes of hepatitis B. The virus that today kills around 620,000 people each year worldwide, it turns out, is old. Really old. A recent study analyzing the history of hepatitis B found that the virus was going around infecting birds at least 82 million years ago.
That ancient bird was the precursor to all modern passerines and neoavian birds and lived during the Late Mesozoic, “back when the dinosaurs were still very much alive,” says the pseudonymous blogger GrrlScientist.
Some time around 82 million years ago, says Science News, “a hepatitis B virus infected an ancient bird and got stuck in its genome.” Normally viruses evolve really quickly. But, once its genes got stuck in the genome of the ancient bird, says GrrlScientist, the rate of change for the virus’ genes “slows to the same pace as that of the host’s DNA,” meaning that scientists looking at modern birds’ genes can see what amounts to a fossilized record of the ancient hepatitis B virus.Science News:
The reconstructed Mesozoic-era virus is remarkably similar to the hepatitis B virus that infects people today, the team found.“We’ve had 82 million years of evolution, but they have the same proteins,” says Suh, who now works at Uppsala University in Sweden.
One exception is a notorious protein called X protein. The protein has been implicated in causing liver cancer and is necessary for the virus to replicate in humans. Since X protein is missing from the hepatitis B viruses that infect modern-day birds, many scientists thought that bird viruses had lost the protein during evolution. But the ancient virus doesn’t contain X protein either, which means that the bird version probably never had it, and X marked mammalian hepatitis B viruses only recently.
So, the researchers think that birds got hepatitis B first, and then it later learned to live in mammals. In the study, the scientists say that learning about the virus’ long history can help us understand how it evolved. They also say that it could help with the “in-vitro resurrection of Mesozoic hepadnaviruses.” But maybe we can skip that part.
Ancient Dinosaur Birds Were Infected With Hepatitis B | Smart News | Smithsonian https://www.smithsonianmag.com/smart-news/ancient-dinosaur-birds-were-infected-with-hepatitis-b-8381925/
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