中文导读 一个病毒到底“攻击谁”，决定了科学家该从哪里研究它对健康的影响。文章先交代一个持续近 40 年的看法：肠道中常见的 picobirnavirus 常在腹泻病人的样本里出现，因此被认为会感染人体细胞。接着解释这一判断为何会形成，以及研究团队如何从一种实验用小线虫身上得到线索，再通过无菌小鼠、无氧培养和抗生素实验，一步步证明它其实在细菌体内繁殖。最后，文章提醒读者：病毒不直接感染人体，并不等于完全无害，它可能通过破坏有益细菌间接影响健康，但目前的关联还不能证明它会致病。阅读时可留意 however、yet、still 等词如何引出转折，以及 suggests、appears、may 等词如何表达研究结论的确定程度。
正文 For almost 40 years , scientists thought they understood a common virus that lives in the human gut . Known as picobirnavirus , it was often found in people with stomach problems , so many experts believed it attacked human cells . A new study published on October 29 in the journal Nature Microbiology suggests that this idea was wrong . The virus appears to infect bacteria instead .
本段译文 近 40 年来，科学家一直以为自己了解一种生活在人体肠道中的常见病毒。这种病毒名为 picobirnavirus（微小双节 RNA 病毒），常在有肠胃问题的人身上被发现，因此许多专家认为它会攻击人体细胞。10 月 29 日发表在《自然·微生物学》期刊上的一项新研究表明，这种看法是错误的。这种病毒感染的似乎是细菌。
The mistake is easy to understand . Picobirnaviruses were first described in stool samples from patients with diarrhoea , together with well-known stomach viruses such as norovirus . However , scientists could not grow the virus in a laboratory , so they could not see what it really infected . They simply assumed that it was attacking the human body .
本段译文 这个误会不难理解。微小双节 RNA 病毒最早是在腹泻病人的粪便样本中被描述的，与诺如病毒等知名的肠胃病毒一同出现。然而，科学家无法在实验室中培养这种病毒，因此无法看到它真正感染的是什么。他们只是假定它在攻击人体。
The first clue came from an unexpected place . Researchers led by David Wang at Washington University School of Medicine in St . Louis found genetic traces of the virus while studying a tiny worm that is often used in genetics research Worms and humans are very different , but both live with bacteria worms eat them , and people carry trillions of them in their gut . This made the team ask whether the virus was really a bacteria hunter .
本段译文 第一条线索来自一个意想不到的地方。由圣路易斯华盛顿大学医学院 David Wang 领导的研究人员，在研究一种常用于遗传学研究的微小线虫时，发现了这种病毒的遗传物质痕迹。线虫和人类差别很大，但两者都与细菌共存：线虫以细菌为食，而人的肠道中携带着数万亿个细菌。这让团队开始思考：这种病毒是否其实是细菌的“猎手”。
To test the idea , the researchers put human stool samples into mice that had no microbes of their own . For the first time , the virus could multiply in a laboratory model . The team then grew the virus with gut bacteria in dishes with no oxygen . Human and mouse cells cannot survive without oxygen , yet the virus kept growing for 20 days . When antibiotics killed the bacteria , the virus stopped multiplying . Using special imaging , the team finally found it inside a newly identified type of gut bacteria
本段译文 为了验证这一想法，研究人员把人类粪便样本放入体内没有任何微生物的小鼠中。这种病毒第一次能够在实验室模型中繁殖。随后，团队在无氧的培养皿中让病毒与肠道细菌一起生长。人和小鼠的细胞没有氧气无法存活，但这种病毒在 20 天里持续增长。当抗生素杀死细菌后，病毒也停止了繁殖。借助特殊的成像技术，团队最终在一种新发现的肠道细菌体内找到了它。
According to the university , this makes picobirnaviruses only the third known group of RNA viruses that infect bacteria . Wang said such viruses were thought to be rare in the human body , but this one is common in the gut .
本段译文 据该大学介绍，这使微小双节 RNA 病毒成为已知的第三类感染细菌的 RNA 病毒。Wang 说，这类病毒过去被认为在人体内很少见，但这一种在肠道中很常见。
The finding does not mean the virus is harmless . It has been linked to diarrhoea , type 1 diabetes and a problem that can follow stem cell transplants . It may harm people indirectly by destroying helpful gut bacteria , which could let harmful microbes grow . Still , Wang warned that finding high levels of the virus in sick patients does not prove that it causes disease . It may simply be a sign that something is wrong in the gut . As he put it , the first step to understanding a virus is knowing what it infects
本段译文 这一发现并不意味着这种病毒是无害的。它曾被发现与腹泻、1 型糖尿病以及干细胞移植后可能出现的一种并发症有关。它可能通过破坏有益的肠道细菌间接伤害人体，从而让有害微生物得以生长。不过，Wang 提醒说，在患者体内发现大量这种病毒，并不能证明它会导致疾病。它也许只是肠道出现问题的一个信号。用他的话说，了解一种病毒的第一步，是弄清它感染的是什么。
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