2022年经济学人 儿童不明原因肝炎是怎么回事？(2)（在线收听）

Aav2 is a parvovirus that cannot replicate 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 contagious.

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 dormant 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 genes.

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 gene 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 copious 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 mechanism 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 immunity 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 bugs 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。