2022年经济学人 儿童不明原因肝炎是怎么回事？(2)

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Aav2 is a parvovirus that cannot replicate¹ on its own but needs assistance from a “helper” virus such as an adenovirus or a herpesvirus.

Aav2是一种不能自行复制的细小病毒，但需要腺病毒或疱疹病毒等“辅助”病毒的帮助。

It is not known for causing illness but it is very contagious².

虽然不知道它会导致疾病，但它的传染性很强。

Most children are exposed to it at a young age and it lays dormant³ in the cells, including those of the liver, until infection with a helper virus triggers its replication.

大多数儿童在很小的时候就接触到它，它在肝脏细胞等细胞中休眠，直到感染辅助病毒触发它的复制。

The results from the two studies suggest that coinfection by aav2 and adenovirus -- or sometimes possibly a herpesvirus called hhv6, which was found in a few children -- is the cause of the mysterious hepatitis illness.

这两项研究的结果表明，aav2和腺病毒(有时可能是在一些儿童体内发现的一种名为hhv6的疱疹病毒)的共同感染是神秘的肝炎疾病的原因。

Given how much aav2 and adenovirus circulate, lots of children probably get co-infected.

考虑到aav2和腺病毒的传播量，许多儿童可能会同时感染。

Why, then, do only a small number of them develop the strange hepatitis?

那么，为什么只有一小部分人会患上这种奇怪的肝炎呢？

The researchers in Glasgow looked for an answer in the children’s genes⁵.

格拉斯哥的研究人员在孩子们的基因中寻找答案。

In eight of the nine children with the strange hepatitis they found variations in the Human Leukocyte Antigen gene⁴ that were not commonly found in the 58 comparison children.

在9名患有奇怪肝炎的儿童中，有8名发现了人类白细胞抗原基因的变异，而这在58名对照儿童中并不常见。

The prevalence of these specific variations is highest in northern Europe -- the region where most of the strange hepatitis cases have been reported.

这些特殊变异的流行率在北欧最高，大多数不明原因肝炎病例都来自这里。

It is unclear how aav2 is causing the illness.

目前还不清楚aav2是如何导致这种疾病的。

The researchers did not find viral particles in the samples taken when the children were ill, but detected large amounts of rna traces of aav2 -- which suggest that copious⁶ replication had happened in the past.

研究人员在儿童患病时采集的样本中没有发现病毒颗粒，但检测到了大量aav2的RNA痕迹-这表明过去曾发生过大量复制。

This means that an indirect viral mechanism⁷ may be responsible, such as an immune reaction to aav2 that leads, in rare cases, to acute liver inflammation.

这意味着一种间接的病毒机制可能起作用，例如对aav2的免疫反应，在罕见情况下导致急性肝炎症。

Such cases of unexplained hepatitis are not new.

这类原因不明的肝炎病例并不新鲜。

But lowered immunity⁸ to viruses among children as a result of less mixing during the covid-19 pandemic led to many such cases at the same time.

但在新冠肺炎大流行期间，由于儿童与病毒接触较少，导致儿童对病毒的免疫力降低，导致许多此类病例同时发生。

The world is acutely aware that exposure to novel viruses can cause pandemics, but a lack of exposure to bugs⁹ can cause problems too.

全世界都敏锐地意识到，接触新型病毒会导致大流行，但缺乏对细菌的接触也会造成问题。

1 replicate   

v.折叠，复制，模写；n.同样的样品；adj.转折的

参考例句：

• The DNA of chromatin must replicate before cell division.染色质DNA在细胞分裂之前必须复制。
• It is also easy to replicate,as the next subsection explains.就像下一个小节详细说明的那样，它还可以被轻易的复制。

2 contagious   

adj.传染性的，有感染力的

参考例句：

• It's a highly contagious infection.这种病极易传染。
• He's got a contagious laugh.他的笑富有感染力。

3 dormant   

adj.暂停活动的；休眠的；潜伏的

参考例句：

• Many animals are in a dormant state during winter.在冬天许多动物都处于睡眠状态。
• This dormant volcano suddenly fired up.这座休眠火山突然爆发了。

4 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

5 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

6 copious   

adj.丰富的，大量的

参考例句：

• She supports her theory with copious evidences.她以大量的例证来充实自己的理论。
• Every star is a copious source of neutrinos.每颗恒星都是丰富的中微子源。

7 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

8 immunity   

n.优惠；免除；豁免，豁免权

参考例句：

• The law gives public schools immunity from taxation.法律免除公立学校的纳税义务。
• He claims diplomatic immunity to avoid being arrested.他要求外交豁免以便避免被捕。

9 bugs   

adj.疯狂的，发疯的n.窃听器( bug的名词复数 )；病菌；虫子；[计算机]（制作软件程序所产生的意料不到的）错误

参考例句：

• All programs have bugs and need endless refinement. 所有的程序都有漏洞，都需要不断改进。 来自《简明英汉词典》
• The sacks of rice were swarming with bugs. 一袋袋的米里长满了虫子。 来自《简明英汉词典》