atepeq/tico19 huggingface dataset:
However, it is more pathogenic than community-acquired HCoVs and less pathogenic than SARS-CoV or MERS-CoV.
但是，它比社区获得性 HCoV 的致病性更高，比 SARS-CoV 或 MERS-CoV 的致病性更低。
It remains to be seen whether it will adapt fully to humans and circulate within humans without a reservoir or intermediate animal host.
它是否能完全适应人类，并在没有宿主或中间动物宿主的情况下在人类内部循环传播，仍有待观察。
Before discussing the animal origins of HCoVs, it will serve us well to discuss the definitions and characteristics of evolutionary, natural, reservoir, intermediate and amplifying hosts of HCoVs.
在讨论 HCoV 的动物起源之前，先讨论 HCoV 的进化宿主、自然宿主、贮存宿主、中间宿主和扩大宿主的定义与特征，对我们有一定的指导意义。
An animal serves as the evolutionary host of an HCoV if it harbours a closely related ancestor sharing high homology at the level of nucleotide sequence.
如果某一动物具有在核苷酸序列水平上高度同源的密切相关祖先，则该动物将成为 HCoV 的进化宿主。
The ancestral virus is usually well adapted and non-pathogenic in this host.
祖先病毒通常在此宿主中适应性强且无致病性。
Likewise, a reservoir host harbours HCoV continuously and for long term.
同样，贮存宿主也会长期持续地携带 HCoV。
In both cases, the hosts are naturally infected and are the natural hosts of HCoV or its parental virus.
在这两种情况下，宿主都是自然感染的，并且是 HCoV 或其亲代病毒的自然宿主。
In contrast, if the HCoV is newly introduced to an intermediate host right before or around its introduction to humans, it is not well adapted to the new host and is often pathogenic.
相比之下，如果 HCoV刚刚寄生于中间宿主不久后或马上又寄生于人体，那它将无法很好地适应新宿主，并且通常具有致病性。
This intermediate host can serve as the zoonotic source of human infection and play the role of an amplifying host by allowing the virus to replicate transiently and then transmitting it to humans to amplify the scale of human infection.
这种中间宿主可以充当人类感染的人畜共患病源，并通过允许病毒短暂复制，然后将其传播给人类以扩大人类感染的规模，从而发挥放大宿主的作用。
An HCoV can undergo a dead-end infection if it cannot sustain its transmission within the intermediate host.
如果 HCoV 不能在中间宿主内维持其传播，则可能会发生终端感染。
On the contrary, HCoVs can also adapt to the intermediate host and even establish long-term endemicity.
相反，HCoV 也可以适应中间宿主，甚至建立长期的地方性。
In this case, the intermediate host becomes a natural reservoir host.
在这种情况下，中间宿主变成了自然贮存宿主。
Epidemiological data revealed retrospectively that the index case of SARS had a contact history with game animals.
流行病学数据回顾性分析发现，SARS 的索引病例与狩猎动物有接触史。
Subsequent seroprevalence investigations indicated that animal traders had a higher prevalence of anti-SARS-CoV IgG compared with that of the general population.
随后的血清阳性率调查表明，与一般人群相比，动物商贩体内抗SARS-CoV的免疫球蛋白G（IgG）水平更高。
Masked palm civets (Paguma larvata) and a racoon dog in live animal markets were first identified to carry SARS-CoV-like viruses that are almost identical to SARS-CoV.
在活体动物市场上，果子狸（花面狸）和一只狸猫首次被发现携带了与 SARS-CoV 病毒几乎完全相同的 SARS-CoV 样病毒。
This was indirectly supported by the fact that no further SARS was reported after killing all civets in the markets.
在清除掉市场中的所有果子狸后，没有进一步的 SARS 报告，这一事实间接支持了上述观点。
However, it has been reported that masked palm civets from the wild or farms without exposure to the live animal markets were largely negative for SARS-CoV, suggesting that masked palm civets might only serve as the intermediate amplifying host but not the natural reservoir of SARS-CoV.
然而，报告称，野生或未接触活体动物市场的农场果子狸对 SARS-CoV 的检测基本呈阴性，这表明果子狸可能只是中间放大宿主，而不是 SARS-CoV 的自然宿主。
Notably, since 80% of the different animals in the markets in Guangzhou have anti-SARS-CoV antibodies, the possibilities that multiple species of small mammals might also serve as intermediate amplifying hosts of SARS-CoV cannot be excluded.
值得注意的是，由于广州市场上 80% 的不同动物都有 SARS-CoV 抗体，因此不能排除多种小型哺乳动物也可能充当 SARS-CoV 中间扩大宿主的可能。
All of these appear to be dead-end hosts of SARS-CoV.
所有这些动物似乎都是 SARS-CoV 的终端宿主。
Subsequent search for the natural animal host of SARS-CoV unveiled a closely related bat CoV, termed SARS-related Rhinolophus bat CoV HKU3 (SARSr-Rh-BatCoV HKU3), which exists in Chinese horseshoe bats.
随后对 SARS-CoV 自然动物宿主的研究发现了一种密切相关的蝙蝠冠状病毒，称为和SARS相关的菊头蝠冠状病毒HKU3 (SARSr-Rh-BatCoV HKU3)，存活于中华菊头蝠体内。
These bats are positive for anti-SARS-CoV antibodies and genome sequence of SARSr-Rh-BatCoV HKU3.
这些蝙蝠对 SARS-CoV 抗体和 SARSr-Rh-BatCoV HKU3 的基因组序列呈阳性。
This and other bat CoVs share 88-92% nucleotide sequence homology with SARS-CoV.
该病毒及其他蝙蝠冠状病毒与 SARS-CoV 具有 88-92% 的核苷酸序列同源性。
These studies have laid the foundation for the new concept that bats host emerging human pathogens.
这些研究为蝙蝠是新出现的人类病原体的宿主这一新概念奠定了基础。
Several SARS-like CoVs (SL-CoVs) have also been identified from bats, but none except for one designated WIV1 can be isolated as live virus.
此外，研究者还从蝙蝠中鉴定出多种 SARS 样冠状病毒 (SL-CoV)，但除一种指定的 WIV1 外，没有任何病毒可以作为活病毒分离出来。
Human angiotensin converting enzyme 2 (ACE2) is known to be the receptor of SARS-CoV.
人血管紧张素转换酶 2 (ACE2) 是已知的 SARS-CoV 的受体。
WIV1 derived from fecal sample of bats was demonstrated to use bat, civet and human ACE2 as receptor for cell entry.
实验证明，从蝙蝠粪便样本中提取的 WIV1 使用蝙蝠、果子狸和人 ACE2 作为其进入细胞的受体。
Intriguingly, sera of convalescent SARS patients were capable of neutralizing WIV1.
有趣的是， SARS 恢复期患者的血清能够中和 WIV1。
Thus far, WIV1 represents the most closely related ancestor of SARS-CoV in bats, sharing 95% nucleotide sequence homology.
迄今为止，WIV1 是与蝙蝠 SARS-CoV 最接近的祖先，具有 95% 的核苷酸序列同源性。
Albeit the high homology between these two viruses, it is generally believed that WIV1 is not the immediate parental virus of SARS-CoV and bats are not the immediate reservoir host of SARS-CoV.
尽管这两种病毒高度同源，但通常认为 WIV1 不是 SARS-CoV 的直接亲代病毒，蝙蝠也不是 SARS-CoV 的直接贮存宿主。
Phylogenetic analysis clusters MERS-CoV to the same group as bat CoV-HKU4 and bat CoV-HKU5.
系统发育分析将 MERS-CoV 与蝙蝠 CoV-HKU4 和蝙蝠 CoV-HKU5 归为同一组。
Bat CoV-HKU4 and MERS-CoV utilize the same host receptor, dipeptidyl peptidase 4 (DPP4), for virus entry.
蝙蝠 CoV-HKU4 和 MERS-CoV 利用相同的宿主受体二肽基肽酶4 (DPP4) 侵入病毒。
RNA-dependent RNA polymerase sequences of MERS-CoV are phylogenetically closer to counterparts in bat beta-CoVs identified from Europe and Africa.
MERS-CoV 的 RNA 依赖性 RNA 聚合酶序列在系统发育上与来自欧洲和非洲的蝙蝠 β-CoV 中的对应 RNA 更接近。
Up to now, no live MERS-CoV can be found in wild bats.
到目前为止，未在野生蝙蝠体内发现活的 MERS-CoV。
MERS-CoV and its closest relative bat CoV-HKU25 share only 87% nucleotide sequence homology.
MERS-CoV 与它的近亲蝙蝠 CoV-HKU25 仅具有 87% 的核苷酸序列同源性。
Thus, bats might not be the immediate reservoir host of MERS-CoV.
因此，蝙蝠可能不是 MERS-CoV 的直接贮存宿主。
On the other hand, studies in Middle East have shown that dromedary camels are seropositive for MERS-CoV-specific neutralizing antibodies, same as camels of Middle East origin in multiple African countries.
另一方面，中东的研究表明，单峰驼对 MERS-CoV 特异性中和抗体的血清呈阳性，与多个非洲国家的起源于中东的骆驼一样。
Live MERS-CoV identical to the virus found in humans was isolated from the nasal swabs of dromedary camels, further indicating that camels serve as the bona fide reservoir host of MERS-CoV.
从单峰驼的鼻拭子中分离出的活 MERS-CoV与人体发现的病毒相同，这进一步表明骆驼是 MERS-CoV 真正的贮存宿主。
It is also noteworthy that generally mild symptoms but massive virus shedding were observed in camels experimentally infected with MERS-CoV.
同样需要指出的是，在实验性感染 MERS-CoV 的骆驼中，一般症状轻微，但观察到大量病毒脱落。
Notably, infected camels shed viruses not only through respiratory route but also through fecal-oral route, which is also the main route for virus shedding from bats.
值得注意的是，受感染的骆驼不仅通过呼吸道传播病毒，还通过粪口途径传播病毒，而粪口途径也是蝙蝠散发病毒的主要途径。
However, questions still remain since many confirmed cases of MERS have no contact history with camels prior to symptom onset, plausibly ascribed to human-to-human transmission or unknown transmission routes involving unrecognized animal species that harbour MERS-CoV.
然而，问题仍然存在，因为许多 MERS 确诊病例在症状出现之前并没有与骆驼的接触史，这可能归因于人传人或未知的传播途径，包括未被识别的携带 MERS-CoV 的动物物种。
SARS-CoV-2 shares 96.2% nucleotide homology with a bat CoV RaTG13 isolated from Rhinolophus affinis bats.
SARS-CoV-2 与从中菊头蝠分离出的蝙蝠 CoV RaTG13 具有 96.2% 的核苷酸同源性。
As in the cases of SARS-CoV and MERS-CoV, the sequence divergence between SARS-CoV-2 and RaTG13 is too great to assign parental relationship.
与 SARS-CoV 和 MERS-CoV 的情况一样，SARS-CoV-2 和 RaTG13 之间的序列差异太大，无法确定亲代关系。
That is to say, bats might not be the immediate reservoir host(s) of SARS-CoV-2 unless almost identical bat CoVs are found in future.
换言之，除非未来发现几乎相同的蝙蝠冠状病毒，否则蝙蝠可能不是 SARS-CoV-2 的直接贮存宿主。
Presumably, the intermediate animal hosts of SARS-CoV-2 should be among the wildlife species sold and killed at the Huanan Seafood Wholesale Market, with which many of the initial cases of COVID-19 were associated, indicative of a probable animal-to-human transmission event.
据推测，SARS-CoV-2 的中间动物宿主应在华南海鲜批发市场出售和宰杀的野生动物物种中，许多最初的 COVID-19 病例都与之有关，这表明可能发生了动物到人类的传播事件。
Several recent studies based on metagenomic sequencing have suggested that a group of endangered small mammals known as pangolins (Manis javanica) could also harbour ancestral beta-CoVs related to SARS-CoV-2.
最近几项基于宏基因组测序的研究表明，一种被称为穿山甲（马来穿山甲）的濒危小型哺乳动物也可能携带与 SARS-CoV-2 相关的祖先 β-CoV。
These novel pangolin CoV genomes share 85-92% nucleotide sequence homology with SARS-CoV-2.
这些新的穿山甲冠状病毒基因组与 SARS-CoV-2 具有 85-92% 的核苷酸序列同源性。
However, they are equally closely related to RaTG13 with about 90% identity at the level of nucleotide sequence.
但它们与 RaTG13 的关系同样密切，在核苷酸序列水平上约有 90% 的同源性。
They cluster into two sub-lineages of SARS-CoV-2-like viruses in the phylogenetic tree, one of which share a more similar receptor binding domain (RBD) with SARS-CoV-2, with 97.4% amino acid sequence identity.
在系统发育树中，它们被归类为两个 SARS-CoV-2 样病毒亚系，其中一个与 SARS-CoV-2 有更相似的受体结合域 (RBD)，并具有 97.4% 的氨基酸序列同源性。
In stark contrast, the RBDs of SARS-CoV-2 and RaTG13 are more divergent, albeit a higher degree of sequence homology genome-wide.
与之形成鲜明对比的是，SARS-CoV-2 和 RaTG13 的 RBD 差异更大，尽管二者全基因组的序列同源性更高。
An earlier study on diseased pangolins also reported the detection of viral contigs from lung samples, which turn out to be similarly related to SARS-CoV-2.
早前的一项关于患病穿山甲的研究也报告了从肺样本中检测到病毒重叠群，结果也与 SARS-CoV-2 有类似的关系。
This study adopted different assembly methods and manual curation to generate a partial genome sequence comprising about 86.3% of the full-length viral genome.
这项研究采用了不同的组装方法和人工处理，获得了约占病毒全基因组 86.3% 的部分基因组序列。
We cannot exclude the possibility that pangolin is one of the intermediate animal hosts of SARS-CoV-2.
我们无法排除穿山甲是 SARS-CoV-2 中间动物宿主之一的可能。
However, currently there is no evidence in support of a direct pangolin origin of SARS-CoV-2 due to the sequence divergence between SARS-CoV-2 and pangolin SARS-CoV-2-related beta-CoVs.
然而，由于 SARS-CoV-2 与穿山甲 SARS-CoV-2 相关的 β-CoV 序列存在差异，因此目前尚无证据表明 SARS-CoV-2 直接来源于穿山甲。
In addition, the distance between SARS-CoV-2 and RaTG13 is even shorter than that between SARS-CoV-2 and pangolin SARS-CoV-2-related beta-CoVs.
此外，SARS-CoV-2 与 RaTG13 之间的距离甚至比 SARS-CoV-2 与穿山甲 SARS-CoV-2 相关的 β-CoV 之间的距离更短。
The evolutionary pathway of SARS-CoV-2 in bats, pangolins and other mammals remains to be established.
SARS-CoV-2 在蝙蝠、穿山甲和其他哺乳动物中的进化路径仍有待确定。
Whereas the highest sequence homology has been found in the RBDs between SARS-CoV-2 and pangolin, SARS-CoV-2-related beta-CoVs, SARS-CoV-2 and RaTG13 share the highest genome-wide sequence homology.
尽管在 SARS-CoV-2 和穿山甲之间的 RBD 中发现了最高的序列同源性，但 SARS-CoV-2 相关的 β-CoV、SARS-CoV-2 和 RaTG13 具有最高的全基因组序列同源性。
It is highly speculative that the high degree of similarity between the RBDs of pangolin SARS-CoV-2-related beta-CoVs and SARS-CoV-2 is driven by selectivity-mediated convergent evolution.
可以高度推测的是，穿山甲 SARS-CoV-2 相关 β-CoV 与 SARS-CoV-2 的 RBD 之间的高度相似性是由选择性介导的趋同进化引起的。
A counter-proposal is in favour of a recombination between a pangolin SARS-CoV-2-related beta-CoV and RaTG13 in the third wild animal species.
另一种相反的观点是，穿山甲 SARS-CoV-2 相关的 β-CoV 与 RaTG13 在第三种野生动物物种中重组。
As a driving force in evolution, recombination is widespread among beta-CoVs.
作为进化的驱动力，重组在 β-CoV 中广泛存在。
The jury is still out on the immediate zoonotic origin of SARS-CoV-2.
关于 SARS-CoV-2 的直接人畜共患病起源，目前尚无定论。
Besides the highly pathogenic HCoVs, the zoonotic origin of HCoV-229E, HCoV-OC43, HCoV-NL63 and HCoV-HKU1 have also been studied.
除了高致病性 HCoV 外，研究者还研究了 HCoV-229E、HCoV-OC43、HCoV-NL63 和 HCoV-HKU1 的人畜共患病起源。
Phylogenetic evidence indicated that both HCoV-NL63 and HCoV-229E might have originated from bat CoVs, while the parental viruses of HCoV-OC43 and HCoV-HKU1 have been found in rodents.
系统发育学证据表明，HCoV-NL63 和 HCoV-229E 可能都起源于蝙蝠冠状病毒，而 HCoV-OC43 和 HCoV-HKU1 的亲代病毒也已在啮齿动物中发现。
It has been reported that a bat CoV termed ARCoV.2 (Appalachian Ridge CoV) detected in North American tricolored bat displayed close relationship with HCoV-NL63.
报告称，在北美三色蝙蝠中发现的称为ARCoV.2 (Appalachian Ridge CoV) 的蝙蝠冠状病毒显示与 HCoV-NL63 密切相关。
On the other hand, HCoV-229E was genetically related to another bat CoV, termed Hipposideros/GhanaKwam/19/2008, which was detected in Ghana, while camelids have also been suspected as its intermediate host.
另一方面，HCoV-229E 与在加纳发现的另一种蝙蝠冠状病毒（称为Hipposideros/GhanaKwam/19/2008）有基因上的联系，而骆驼科动物也被怀疑是其中间宿主。
For clarity, the current knowledge on animal origins of known HCoVs is summarized in Figure ​1 and Table 2.
为清楚起见，图 1 和表 2 总结了有关已知 HCoV 的动物起源的现有知识。
Phylogenetic analysis has provided evidence for interspecies transmission events of HCoVs in the history.
系统发育分析为历史上 HCoV 的种间传播事件提供了证据。
When HCoV-OC43 crossed species to infect humans from domestic livestock around 1890, a pandemic of respiratory infection was recorded.
在 1890 年前后，当 HCoV-OC43 从家畜跨物种感染人类时，就出现了呼吸道传染病的大流行。
The interspecies transmission history of HCoV-229E is less clear.
HCoV-229E 的种间传播历史尚不明朗。
Bat alpha-CoVs closely related to HCoV-229E have been found.
与HCoV-229E密切相关的蝙蝠α-CoV已被发现。
Between them there is an alpaca alpha-CoV.
在二者之间出现了一种羊驼 α-CoV。
Several lines of evidence support the transmission of virus from bats to humans directly.
有多条证据支持病毒从蝙蝠直接传播给人类。
First, humans but not alpacas might have contact with bats in a shared ecological niche.
首先，人类而非羊驼，可能会在共同的生态位中与蝙蝠接触。
Instead, humans have close contact with alpacas.
相反的是，人类与羊驼有着密切的接触。
Second, HCoV-229E-related bat alpha-CoVs are diverse and non-pathogenic in bats, whereas alpaca alpha-CoV caused an outbreak of respiratory disease in infected animals.
其次，与 HCoV-229E 相关的蝙蝠 α-CoV 在蝙蝠中具有多样性和非致病性，而羊驼 α-CoV 则在受感染动物中引起了呼吸道疾病的爆发。
Finally, alpaca alpha-CoV has not been found in feral animals.
最后，未在野生动物中发现羊驼 α-CoV。
Thus, the possibility cannot be excluded that alpacas obtain the HCoV-229E-related alpha-CoV from humans.
因此，不能排除羊驼从人类中获得 HCoV-229E 相关的 α-CoV 的可能性。
In fact, bats are the direct source of human pathogenic viruses including rabies virus, Ebola virus, Nipah virus and Hendra virus.
事实上，蝙蝠是包括狂犬病毒、埃博拉病毒、尼帕病毒和亨德拉病毒在内的人类致病性病毒的直接来源。
It is therefore not too surprising that bats might transmit HCoV-229E to humans directly.
因此，蝙蝠将 HCoV-229E 直接传播给人类也就不足为奇了。
Alternatively, whereas bat alpha-CoVs serve as the gene pool of HCoV-229E, alpacas and dromedary camels might serve as intermediate hosts that transmit viruses to humans, exactly as in the case of MERS-CoV.
或者，尽管蝙蝠 α-CoV 充当着 HCoV-229E 的基因库，但羊驼和单峰驼可能是将病毒传播给人类的中间宿主，这与 MERS-CoV 的情况完全相同。
MERS-CoV serves as an excellent example of interspecies transmission from bats to dromedary camels and from dromedary camels to humans.
MERS-CoV 很好地说明了从蝙蝠到单峰驼以及从单峰驼到人类的种间传播。
The evolutionary origin of MERS-CoV from bats is known at its initial identification and has also been strengthened by subsequent findings.
蝙蝠的 MERS-CoV 进化起源在其最初的鉴定中就已为人所知，随后的发现也强化了这一论点。
It is obvious that bats provide a rich pool of virus species for interspecies exchange of genetic fragments and interspecies transmission.
显然，蝙蝠为基因片段的种间交换和种间传播提供了丰富的病毒种类库。
Longevity, densely packed colonies, close social interaction and strong ability to fly are all favourable conditions for bats to be an ideal 'virus spreader'.
长寿且密集的群体、紧密的社会性互动和强大的飞行能力都是蝙蝠成为理想的“病毒传播者”的有利条件。
On the other hand, MERS-CoV has been introduced to dromedary camels for decades.
另一方面，MERS-CoV 进入单峰驼体内已有数十年时间。
It is well adapted to these camels that have turned from an intermediate host to a stable and natural reservoir host.
它很好地适应了这些骆驼，而骆驼也已从中间宿主变成稳定的自然贮存宿主。
MERS-CoV causes very mild disease and maintains a relatively low mutation rate in these animals.
MERS-CoV 在这些动物中引起非常轻微的疾病，并保持相对低的突变率。
Its sporadic transmission to humans is an accident and humans remain a dead-end host of MERS-CoV as its transmission cannot be sustained.
它对人类的零星传播是一种意外，而由于无法持续传播，人类仍然是 MERS-CoV 的终端宿主。
In contrast to the role of camels in the transmission of MERS-CoV, the role of pangolins, if there is any, in the transmission of SARS-CoV-2 is different.
与骆驼在 MERS-CoV 传播中的作用相比，穿山甲在 SARS-CoV-2 传播中的作用（如果有）是不同的。
Particularly, pangolin beta-CoVs are highly pathogenic in pangolins.
特别是，穿山甲 β-CoV 在穿山甲中具有高致病性。
They might be a dead-end host for SARS-CoV-2-related beta-CoVs, similar to civets in the case of SARS-CoV.
它们可能是 SARS-CoV-2 相关的 β-CoV 的终端宿主，类似于 SARS-CoV 中的果子狸。
Several possibilities for interspecies transmission of SARS-CoV-2 from animals to humans have to be ruled in or ruled out in future studies.
在未来的研究中必须确定或排除 SARS-CoV-2 从动物向人类的种间传播的几种可能。
First, bats could be the reservoir host of a SARS-CoV-2-related virus almost identical to SARS-CoV-2.
首先，蝙蝠可能是与 SARS-CoV-2 几乎完全相同的 SARS-CoV-2 相关病毒的贮存宿主。
Humans might share the ecological niche with bats through butchering or coal mining.
人类可能会通过屠宰或煤矿开采与蝙蝠共享生态位。
Second, pangolins could be one of intermediate amplifying host to which a SARS-CoV-2-related virus had been newly introduced.
其次，穿山甲可能是 SARS-CoV-2 相关病毒新入侵的中间扩大宿主之一。
Humans contract the virus through butchering and consumption of game meat.
人类通过宰杀和食用野味而感染病毒。
It is possible that many mammals including domestic animals are susceptible to SARS-CoV-2.
包括家畜在内的许多哺乳动物可能都容易感染 SARS-CoV-2。
A survey of domestic and wild animals for antibodies is warranted.
有必要对家畜和野生动物进行抗体调查。
Third, as mentioned above, recombination and adaptation of SARS-CoV-2 might have occurred in a third species that has contact with both bats and pangolins.
第三，如上所述，SARS-CoV-2可能在与蝙蝠和穿山甲都接触过的第三个物种中进行重组和适应。
The search for the animal origins of SARS-CoV-2 is still on.
对 SARS-CoV-2 的动物起源的研究仍在继续。
Apart from different types of the animal hosts, three major factors on the viral side are also important in facilitating CoVs to cross species barriers.
除了不同类型的动物宿主外，病毒方面的三个主要因素在促进冠状病毒跨越种间屏障方面也发挥了重要作用。
First of all, their relatively high mutation rates in RNA replication.
首先，它们在 RNA 复制中具有较高的突变率。
In comparison to other single-stranded RNA viruses, the estimated mutation rates of CoVs could be regarded as “moderate” to “high” with an average substitution rate being ~10-4 substitution per year per site 2, depending on the phase of CoV adaptation to novel hosts.
与其他单链 RNA 病毒相比，冠状病毒的突变率估计为“中等”到“高”，根据冠状病毒对新宿主的适应阶段，每个位点 2 每年的平均替代率约为 10-4 次。
CoVs have a proof-reading exoribonuclease, deletion of which results in exceedingly high mutability and attenuation or even inviability.
冠状病毒具有校对活性的核糖核酸外切酶，将其删除会导致非常高的可变性和衰减，甚至无法生存。
Interestingly, the nucleotide analogue Remdesivir is known to suppress CoV replication through inhibition of this exoribonuclease and the RNA-dependent RNA polymerase.
有趣的是， 已知核苷类似物瑞德西韦 (Remdesivir)可通过抑制这种核糖核酸外切酶和 RNA 依赖性 RNA 聚合酶来抑制冠状病毒复制。
Remdesivir is one of most promising anti-SARS-CoV-2 agents to be tested in clinical trials.
瑞德西韦是即将在临床试验中测试的最有希望的抗 SARS-CoV-2 药物之一。
Nevertheless, mutation rates of CoVs are about a million times higher than those of their hosts.
然而，冠状病毒的突变率比其宿主高约 100 万倍。
In addition, mutation rate is often high when CoVs are not well adapted to the host.
另外，如果冠状病毒不能很好地适应宿主，则其突变率通常会很高。
Compared to SARS-CoV with a high mutation rate, the mutation rate of SARS-CoV-2 is apparently lower, suggestive of a higher level of adaptation to humans.
与具有高突变率的 SARS-CoV 相比，SARS-CoV-2 的突变率明显更低，表明其对人类的适应性更高。
Presumably, it has already been adapted to another host close to humans.
可以推测，它已经适应了另一种接近人类的宿主。
In addition to SARS-CoV-2, this also applies to MERS-CoV, which is well adapted to dromedary camels.
除 SARS-CoV-2 外，这也适用于很好地适应了单峰驼的 MERS-CoV。
Theoretically, it is unlikely that genetic drift would render vaccines and antivirals against SARS-CoV-2 ineffective quickly.
从理论上讲，基因漂变不大可能会使针对 SARS-CoV-2 的疫苗和抗病毒药迅速失效。
Second, the large RNA genome in CoVs exerts extra plasticity in genome modification for mutations and recombination, thereby increasing the probability for interspecies co-evolution, which is advantageous for the emergence of novel CoVs when the conditions become appropriate.
其次，冠状病毒中较大的 RNA 基因组在基因突变和重组的修饰中具有额外的可塑性，从而增加了种间协同进化的可能，这在条件合适时有利于新型冠状病毒的出现。
This is supported by the copious unique open reading frames and protein functions encoded towards the 3′ end of the genome.
朝向基因组 3' 末端编码的大量独特的开放阅读框和蛋白质功能为此提供了证据。
Third, CoVs randomly and frequently switch templates during RNA replication through a unique “copy-choice” mechanism.
第三，冠状病毒在 RNA 复制过程中通过独特的“复制选择”机制随机且频繁地切换模板。
In a host that serves as the mixing vessel, strand switching occurs frequently during CoV RNA transcription.
在作为混合容器的宿主中，CoV RNA 转录过程中会频繁发生链交换。
Highly homologous full-length and subgenomic RNAs could recombine to generate new CoVs.
高度同源的全长和亚基因组 RNA 可以重组产生新的冠状病毒。
Phylogenetic evidence of natural recombination has been found in both HCoV-HKU1 and HCoV-OC43, as well as animal CoVs such as bat SL-CoV and batCoV-HKU9.
在 HCoV-HKU1 和 HCoV-OC43 以及蝙蝠 SL-CoV 和蝙蝠 CoV-HKU9 等动物冠状病毒中都发现了自然重组的系统发育学证据。
Virus-host interaction in relation to transmission
与传播相关的病毒-宿主相互作用
Besides three viral factors stated above, viral interaction with host receptor is another key factor influential on interspecies transmission.
除上述三个病毒因素外，病毒与宿主受体的相互作用是影响种间传播的另一个关键因素。
Herein, recombination of SARS-CoV is taken as a typical example, which also showed evidence of positive selection during interspecies transmission events.
本文以 SARS-CoV 的重组为典型例子，显示了在种间传播事件中存在正向选择的证据。
Based on the comparative analysis between isolates of human and civet SARS-CoVs, SARS-CoV is thought to undergo rapid adaptation in different hosts, particularly with mutations at the RBD of the S protein.
基于对人与果子狸 SARS-CoV 分离菌株的比较分析，研究人员认为SARS-CoV可以快速适应不同宿主，特别是通过S 蛋白RBD的突变来实现这一过程。
Generally, the RBD in the S protein of a CoV interacts with the cellular receptor and is intensely selected by the host antibody response.
通常，冠状病毒 S 蛋白中的 RBD 会与细胞受体相互作用，并会受到宿主抗体反应的严密筛选。
In SARS-CoV, the RBD is in the 318th to 510th amino acids on the S1 fragment, which binds to the human ACE2 as well as its coreceptors for viral entry.
在 SARS-CoV 中，RBD 位于 S1 片段的第 318 至 510 个氨基酸中，它与人 ACE2 及其共受体结合，以使病毒进入。
The RBD of SARS-CoV is capable of recognizing the ACE2 receptors of various animals, including bat, civet, mouse and raccoon dog, allowing interspecies transmission of the virus.
SARS-CoV 的 RBD 能够识别各种动物的 ACE2 受体，包括蝙蝠、果子狸、老鼠和狸猫，从而使病毒在种间传播。
In fact, only 6 amino acid residues were observed to be different from human and civet viral isolates in the RBD and 4 of them locate in the receptor-binding motif for interaction with the ACE2 receptor.
事实上，在 RBD 中只观察到 6 个与人和果子狸病毒分离株不同的氨基酸残基，其中 4 个残基位于与 ACE2 受体相互作用的受体结合基序中。
Civet SARS-CoV has K479N and S487T mutations in its RBD, which might increase the affinity of the interaction of spike protein with human ACE2 receptor.
果子狸 SARS-CoV 的 RBD 中存在 K479N 和 S487T 突变，这可能会增加纤突蛋白与人 ACE2 受体相互作用的亲和力。
In other words, these two amino acid substitutions might be critical to viral adaption to humans.
换句话说，这两种氨基酸的置换可能对病毒适应人类至关重要。
It is noteworthy that SARS-CoV-2 shares the same cellular receptor with SARS-CoV.
值得注意的是，SARS-CoV-2 与 SARS-CoV 具有相同的细胞受体。
A 30% difference between SARS-CoV-2 and SARS-CoV in the S1 unit of the S protein implicates that the binding affinity of its S protein with human ACE2 might have altered.
SARS-CoV-2 和 SARS-CoV 在 S 蛋白 S1 单元的差异为 30%，这意味着其 S 蛋白与人 ACE2 的结合亲和力可能发生了改变。
Indeed, a cryo-EM study indicates a 10- to 20-fold higher affinity of this binding than that between human ACE2 and SARS-CoV S protein.
的确，一项冷冻电镜研究表明，这种结合的亲和力比人 ACE2 和 SARS-CoV S 蛋白之间的亲和力高 10 至 20 倍。
It will also be of interest to determine whether any other coreceptor might be required for SARS-CoV-2 transmission.
确定在 SARS-CoV-2 传播中是否需要任何其他共受体也将很有意义。
Intriguingly, HCoV-NL63 also binds to ACE2 but with a different part of S.
有趣的是，HCoV-NL63 也与 ACE2 结合，但是与 S 的不同部分结合。
There exist many other HCoV receptors, such as aminopeptidase N for HCoV-229E, and 9-O-acetylated sialic acid for HCoV-OC43.
此外，还有许多其他 HCoV 受体，例如 HCoV-229E 的氨基肽酶 N 和 HCoV-OC43 的 9-O-乙酰化唾液酸。
They might also account for successful adaptation of these CoVs in humans after interspecies transmission from their animal hosts.
它们也可能解释了上述冠状病毒在从动物宿主跨种传播后成功适应人类的原因。
In addition to cellular receptors, the outcome of interspecies transmission of HCoVs is also governed by other host dependency and restriction factors.
除细胞受体外，HCoV 种间传播的结果还受其他宿主依赖性和限制性因素的影响。
The divergence of these host proteins between humans and natural reservoir hosts of HCoVs such as bats, dromedary camels and rodents might constitute a barrier to interspecies transmission.
这些宿主蛋白在人类与蝙蝠、单峰驼和啮齿动物等 HCoV 自然宿主之间的差异可能构成了种间传播的障碍。
HCoVs have to usurp host dependency factors and subvert host restriction factors for a successful interspecies transmission.
HCoV 必须剥夺宿主依赖因素并打破宿主限制因素，才能成功实现种间传播。
In this regard, molecular determinants in this important area of virus-host interaction remain to be identified and characterized.
在此方面，病毒-宿主相互作用这一重要领域中的分子决定因素仍有待确定和表征。
An unbiased genome-wide screening of host dependency and restriction factors for SARS-CoV-2 using the state-of-the-art technology of CRISPR might be fruitful.
利用最新的 CRISPR 技术对 SARS-CoV-2 的宿主依赖性和限制性因素进行无偏倚的全基因组筛选可能会取得成果。
Emergence of novel HCoVs: back to ground zero
新型 HCoV 的出现：回到原点
The diversity of bat CoVs provides ample opportunities for the emergence of novel HCoVs.
蝙蝠冠状病毒的多样性为新型 HCoV 的出现提供了充足的机会。
In this sense, bat CoVs serve as the gene pool of HCoVs.
从这个意义上说，蝙蝠冠状病毒充当了 HCoV 的基因库。
In addition, rapid mutation and genetic recombination also drive HCoV evolution and serve as two important steps in this process.
此外，快速突变和基因重组也是 HCoV 进化的驱动因素，也是此过程的两个重要步骤。
For example, the acquisition or loss of novel protein-coding genes has the potential to drastically modify viral phenotypes.
例如，新蛋白质编码基因的获得或丢失可能会彻底改变病毒的表型。
Among SARS-CoV accessory proteins, ORF8 has been thought to be important in adaptation to humans, as SARS-CoV-related bat viruses were isolated but found to encode divergent ORF8 proteins.
在 SARS-CoV 辅助蛋白中，由于分离出了 SARS-CoV 相关的蝙蝠病毒，但发现它们可以编码不同的 ORF8 蛋白，因此认为 ORF8 对适应人类很重要。
A 29-nucleotide deletion characteristic of SARS-CoVs has been found in strains isolated at the beginning of the human epidemic.
在人类流行病开始时，于分离的病毒株中发现了 SARS-CoV 的 29 个核苷酸缺失特征。
This deletion splits ORF8 into ORF8a and ORF8b and is thought to be an adaptive mutation that promotes the switch of hosts.
这种缺失将 ORF8 分为 ORF8a 和 ORF8b，并被认为是促进宿主转换的适应性突变。
Besides, SARS-CoV has a possible recombination history with lineages of alpha- and gamma-CoVs, where a large number of smaller recombinant regions were identified in the RNA-dependent RNA polymerase.
此外，SARS-CoV 可能与 α- 和 γ-CoV 谱系发生过重组，其中在 RNA 依赖性 RNA 聚合酶中发现了大量较小的重组区域。
Recombination locations were also identified in the nsp9, most of nsp10, and parts of nsp14.
在 nsp9、大部分 nsp10 和部分 nsp14 中也发现了重组位点。
Likewise, it has been shown that the epidemic MERS-CoV experienced recombination events between different lineages, which occurred in dromedary camels in Saudi Arabia.
同样，已有研究表明，MERS-CoV 的流行经历了不同谱系间的重组事件，这发生在沙特阿拉伯的单峰驼中。
Besides SARS-CoV and MERS-CoV, recombination events have also been observed in other HCoVs, in which the HCoVs recombine with other animal CoVs in their non-structural genes.
除 SARS-CoV 和 MERS-CoV 外，在其他 HCoV 中也观察到重组事件，其中 HCoV 与其他动物冠状病毒在其非结构基因中重组。
It should also be cautioned that artificial selection can contribute to unintended changes in viral genomes, most likely resulting from relieving viruses from selection pressures exerted, such as by the host immune system.
还应注意的是，人工选择可能会导致病毒基因组发生意外变化，这很可能是由于减轻了病毒面对的宿主免疫系统等施加的选择压力。
An example of these effects is the loss of a full-length ORF4 in the HCoV-229E prototype strain, owing to a two-nucleotide deletion.
这些作用的一个例子是在 HCoV-229E 原型病毒株中，双核苷酸的缺失导致了全长 ORF4的缺失。
While intact ORF4 could be observed in bat and camel viruses related to HCoV-229E, the alpaca alpha-CoV displays a single nucleotide insertion, resulting in a frameshift.
尽管在与 HCoV-229E 相关的蝙蝠和骆驼病毒中可以观察到完整的 ORF4，但羊驼 α-CoV 显示单个核苷酸插入，引起了移码突变。
Last but not least, the evolution of novel HCoVs is also driven by the selection pressure in their reservoir hosts.
最后但同样重要的是，新型 HCoV 的进化还受到贮存宿主选择压力的驱动。
Asymptomatic or only mild symptoms were detected when bats were infected with CoVs, indicating the mutual adaptation between CoVs and bats.
在蝙蝠感染冠状病毒后，检测到无症状或仅有轻微症状，表明冠状病毒和蝙蝠之间相互适应。
It appeared that bats are well adapted to CoVs anatomically and physiologically.
从解剖学和生理学的角度来看，蝙蝠似乎很好地适应了冠状病毒。
For example, defects in the activation of pro-inflammatory response in bats efficiently reduce the pathology triggered by CoVs.
例如，蝙蝠促炎反应激活的缺陷有效地减少了冠状病毒引发的病理变化。
Besides, the natural killer cell activity in bats is suppressed due to upregulation of inhibitory natural killer cell receptor NKG2/CD94 and low expression level of major histocompatibility complex class I molecules.
此外，由于抑制性自然杀伤细胞受体 NKG2/CD94 的正调控，而且主要组织相容性复合体 I 类分子表达水平较低，因此蝙蝠的自然杀伤细胞活动受到抑制。
Moreover, the high level of reactive oxygen species (ROS) generated from high metabolic activity of bats could both suppress CoV replication and affects proofreading by exoribonuclease, thus providing the selection pressure for the generation of virus strains highly pathogenic when introduced into a new host.
而且，蝙蝠高代谢活性产生的高水平活性氧 (ROS) 既可抑制冠状病毒复制，又可通过核糖核酸外切酶影响校对，从而为病毒株进入新宿主时产生高致病性提供选择压力。
More pathogenic CoV strains might also evolve by recombination, leading to the acquisition of novel proteins or protein features for host adaptation.
更多致病性冠状病毒菌株也可能通过重组进化，导致获得新的蛋白质或蛋白质特征以适应宿主。
Thus, it is not by chance that three novel HCoVs have emerged in the past two decades.
因此，在过去二十年中出现了三种新型 HCoV 并非偶然。
CoVs are non-pathogenic or cause mild symptoms in their reservoir hosts such as bats and camels.
冠状病毒在蝙蝠和骆驼等贮存宿主中不致病或引起轻微症状。
They replicate robustly without eliciting a strong host immune response.
它们进行大量的复制，且不会引起强烈的宿主免疫反应。
Herein lie the secrets of why asymptomatic carriers are seen and what causes the severe cases in human infection.
这就是为什么会出现无症状携带者以及导致人类严重感染病例的原因。
The severe symptoms are mainly due to the hyperactivation of immune response and the cytokine storm wherein the stronger the immune response, the more severe the lung damage.
出现严重症状主要是由于免疫反应的过度激活和细胞因子风暴，因此免疫反应越强，肺部损伤就会越严重。
In contrast, in asymptomatic carriers, the immune response has been de-coupled from CoV replication.
相比之下，在无症状携带者中，免疫反应已经从冠状病毒复制中脱耦。
The same strategy of delinking the immune response might have beneficial effects in anti-SARS-CoV-2 therapy.
使免疫反应脱链的相同策略可能会在抗 SARS-CoV-2 治疗中有积极的作用。
The interferon response is particularly strong in bats.
蝙蝠中的干扰素反应尤为强烈。
Thus, administration of type I interferon at least in the early phase of SARS-CoV-2 infection in humans should be beneficial.
因此，至少在人类 SARS-CoV-2 感染的早期阶段使用 I 型干扰素应该有益。
In addition, NLRP3 inflammasome activation in bats is defective.
此外，蝙蝠中的 NLRP3 炎性体激活也存在缺陷。
By this reasoning, inhibition of NLRP3 inflammasome with MCC950 might be useful in the treatment of COVID-19.
基于此推理，使用 MCC950 抑制 NLRP3 炎性体可能对 COVID-19 的治疗有用。
The emergence of SARS-CoV-2 follows the general theme by which SARS-CoV and MERS-CoV arose.
SARS-CoV-2 的出现遵循着 SARS-CoV 和 MERS-CoV 产生所依据的一般主题。
Whereas a bat beta-CoV sharing 95% nucleotide homology with SARS-CoV has been found, there also exists a bat-CoV sharing 96% nucleotide homology with SARS-CoV-2.
尽管已经发现与 SARS-CoV 具有 95% 核苷酸同源性的蝙蝠 β-CoV，但还有一种蝙蝠冠状病毒与 SARS-CoV-2的核苷酸同源性高达96%。
Whereas civets and other animals in the markets have been found to harbour viruses identical to SARS-CoV, immediate intermediate hosts for SARS-CoV-2 have not been identified.
虽然已发现市场中的果子狸和其他动物携带与 SARS-CoV 相同的病毒，但尚未确定 SARS-CoV-2 的直接中间宿主。
Pangolin beta-CoVs strikingly homologous to SARS-CoV-2 have been found, indicating that pangolins might serve as one of intermediate hosts or pangolin beta-CoVs could contribute gene fragments to the final version of SARS-CoV-2.
目前已发现与 SARS-CoV-2 明显同源的穿山甲 β-CoV，这表明穿山甲可能是中间宿主之一，或穿山甲 β-CoV 可能为最终版的 SARS-CoV-2 贡献了基因片段。
Although questions remain, there is no evidence that SARS-CoV-2 is man-made either deliberately or accidentally.
尽管仍有疑问，但没有证据表明 SARS-CoV-2 是有意或无意人为制造的。
CoVs have returned to the limelight due to the recent outbreak of SARS-CoV-2.
由于近期 SARS-CoV-2 的爆发，冠状病毒重新成为人们关注的焦点。
The study of CoVs in bats and other animals has drastically changed our perception of the importance of zoonotic origins and animal reservoirs of HCoVs in human transmission.
对蝙蝠和其他动物中冠状病毒的研究极大地改变了我们对 HCoV 人畜共患病起源和在人类传播中的动物宿主重要性的认识。
Pervasive evidence has shown that SARS-CoV, MERS-CoV and SARS-CoV-2 have a bat origin and are transmitted to humans via intermediate hosts.
大量证据表明，SARS-CoV、MERS-CoV 和 SARS-CoV-2 起源于蝙蝠，并通过中间宿主传播给人类。
Given that SARS-CoV infection originates from the contact between humans and civets in the markets, closing wet markets and killing civets therein could have effectively ended the SARS epidemic.
鉴于 SARS-CoV 感染源自市场上人类与果子狸之间的接触，关闭湿货市场并杀死果子狸可以有效地结束 SARS 的流行。
By the same reasoning, pangolins should be removed from wet markets to prevent zoonotic transmission, in view of the discovery of multiple lineages of pangolin beta-CoVs closely related to SARS-CoV-2.
同理，鉴于发现了与 SARS-CoV-2 密切相关的穿山甲 β-CoV 的多个谱系，因此应将穿山甲从湿货市场中清除，以防止人畜共患疾传播。
However, whether and how SARS-CoV-2 is transmitted to humans through pangolins and other mammals remain to be clarified in future investigations.
但 SARS-CoV-2 是否以及如何通过穿山甲和其他哺乳动物传播给人类，仍有待进一步研究。
On the other hand, MERS-CoV has existed in dromedary camels for a long time.
另一方面，MERS-CoV 在单峰驼中已经存在了很长时间。
These camels serve as an important tool for transportation as well as a main source of meat, milk, leather and wool products for the local people.
这些骆驼是重要的交通工具，也是当地人的肉、奶、皮革和毛线产品的主要来源。
They are widely distributed across the Middle East and Africa.
它们广泛分布在中东和非洲。
It is therefore impossible to sacrifice all camels for the control of MERS, as what was done in wild animal markets in China to prevent the spreading of SARS-CoV and SARS-CoV-2.
因此，不可能效仿中国野生动物市场为防止SARS-CoV和SARS-CoV-2传播的做法，为控制 MERS 而牺牲掉所有骆驼。
To stop the recurrent outbreaks of MERS, a comprehensive approach should be taken to develop effective vaccines against MERS-CoV for camels, in combination with other infection control measures.
为制止 MERS 的再次暴发，应结合其他感染控制措施，采取综合举措，为骆驼研制有效的抗 MERS-CoV 疫苗。
As we are not able to eliminate these viruses, new genotypes might emerge to cause outbreaks.
由于我们无法消灭这些病毒，新的基因型可能会出现，进而引起疫情爆发。
A variety of zoonotic CoVs are circulating in the wild.
各种人畜共患病冠状病毒在野生环境中循环流动。
Particularly, bat CoVs with zoonotic potential are so diverse.
特别是，具有人畜共患病潜力的蝙蝠冠状病毒多样性颇高。
There are plenty of opportunities that these zoonotic CoVs evolve and recombine, resulting in the emergence of new CoVs that are more transmissible and/or deadly in humans in future.
这些人畜共患病冠状病毒有很多进化和重组的机会，从而导致未来出现在人类中更容易传播和/或致命的新冠状病毒。
The culture of eating wild animals in some places of China should be abandoned to reduce unnecessary contact between humans and animals.
在中国的一些地方，应摒弃食用野生动物的文化，以减少人类和动物之间不必要的接触。
With the ordeals of SARS, MERS and COVID-19, a better preparedness and response plan should be in place.
经过 SARS、MERS 和 COVID-19 的严峻考验，我们应制定更好的防范和应对计划。
In fact, many viruses have existed in the planet for a very long time.
事实上，许多病毒都已在地球上存在了很长时间。
They stay in their own natural reservoirs until there is a chance for spillover.
它们待在自己的自然宿主中，直至出现溢出机会。
Although bats have many features that favours the spreading of viruses, the chance for humans to be in contact with bats and other wildlife species can be minimized if people are educated to stay away from them.
尽管蝙蝠有很多有利于病毒传播的特征，但如果人们受到教育而远离蝙蝠和其他野生物种，那么人类接触蝙蝠和其他野生物种的机会就会极大程度地减少。
Continuous surveillance in mammals is necessary for better understanding of the ecology of CoVs and their natural hosts, which will prove useful in preventing animal-to-human transmission and future outbreaks.
为了更好地了解冠状病毒及其自然宿主的生态状况，有必要对哺乳动物进行连续监测，事实将证明，这对于预防动物向人类传播以及未来的爆发非常有用。
To conclude, the most effective way to prevent viral zoonosis is for humans to stay away from the ecological niches of the natural reservoirs of the zoonotic viruses.
总而言之，预防病毒性人畜共患病最有效的方法是人类应远离人畜共患病毒自然宿主的生态位。
Several pieces in the puzzle of the zoonotic origin of SARS-CoV-2 are still missing.
SARS-CoV-2 的人畜共患病起源之谜中仍有几处缺失。
First, if bats transmit an ancestral virus of SARS-CoV-2 to pangolins, it will be of interest to see under what circumstances bats and pangolins could share the same ecological niche.
首先，如果蝙蝠将一种古老的 SARS-CoV-2 病毒传播给穿山甲，那么考察蝙蝠和穿山甲在什么情况下可以共享同一个生态位是有意义的。
Second, if bats play a more direct role in human transmission, how humans get into contact with bats should be determined.
第二，如果蝙蝠在人类传播中发挥更直接的作用，那么人类如何与蝙蝠接触还有待确定。
Third, if a third mammal acts as the true intermediate host, how it interacts with the different species including humans, bats and pangolins has to be clarified.
第三，如果第三种哺乳动物充当真正的中间宿主，则必须明确它是如何与包括人类、蝙蝠和穿山甲在内的不同物种相互作用的。
Finally, since many mammals including domestic animals might be susceptible to SARS-CoV-2, both surveillance and experimental infection should be conducted.
最后，由于包括家畜在内的许多哺乳动物都可能容易感染 SARS-CoV-2，因此应进行监测和实验性感染研究。
Should it be a bat, a pangolin or another mammal, it is expected that SARS-CoV-2 or its parental viruses that are almost identical will be identified in its natural hosts in future.
如果是蝙蝠、穿山甲或其他哺乳动物，预计未来将会在自然宿主中发现SARS-CoV-2或者与其几乎相同的亲代病毒。
Continued investigations in this area will elucidate the evolutionary pathway of SARS-CoV-2 in animals, with important implications in the prevention and control of COVID-19 in humans.
在这一领域的继续研究将揭示 SARS-CoV-2 在动物中的进化途径，这对人类 COVID-19 的预防和控制具有重要意义。
Preliminary Estimates of the Prevalence of Selected Underlying Health Conditions Among Patients with Coronavirus Disease 2019 — United States, February 12–March 28, 2020
2019 冠状病毒疾病患者部分基础疾病患病率的初步估计 — 美国，2020 年 2 月 12 日至 3 月 28 日
On March 11, 2020, the World Health Organization declared Coronavirus Disease 2019 (COVID-19) a pandemic.
2020 年 3 月 11 日，世界卫生组织宣布 2019 冠状病毒疾病 (COVID-19) 为大流行病。
As of March 28, 2020, a total of 571,678 confirmed COVID-19 cases and 26,494 deaths have been reported worldwide.
截至 2020 年 3 月 28 日，全球总共报告 571,678 名 COVID-19 确诊病例和 26,494 例死亡。
Reports from China and Italy suggest that risk factors for severe disease include older age and the presence of at least one of several underlying health conditions.
来自中国和意大利的报告表明，重症的危险因素包括高龄以及合并几种基础疾病的至少一种。
U.S. older adults, including those aged ≥65 years and particularly those aged ≥85 years, also appear to be at higher risk for severe COVID-19–associated outcomes; however, data describing underlying health conditions among U.S. COVID-19 patients have not yet been reported.
美国的老年人，包括年龄 ≥65 岁的老年人，尤其是年龄 ≥85 岁的老年人，似乎也有发生重症 COVID-19 相关结局的较高风险；但是，尚未报告过美国 COVID-19 患者基础疾病情况的数据。
As of March 28, 2020, U.S. states and territories have reported 122,653 U.S. COVID-19 cases to CDC, including 7,162 (5.8%) for whom data on underlying health conditions and other known risk factors for severe outcomes from respiratory infections were reported.
截至 2020 年 3 月 28 日，美国各州和领地已向 CDC 报告 122,653 名美国 COVID-19 病例，其中 7,162 名 (5.8%) 报告了有关基础疾病以及呼吸道感染严重后果的其他已知危险因素的数据。
Among these 7,162 cases, 2,692 (37.6%) patients had one or more underlying health condition or risk factor, and 4,470 (62.4%) had none of these conditions reported.
在这 7,162 起病例中，有 2,692 名 (37.6%) 患者存在一种或多种基础疾病或危险因素，而 4,470 名 (62.4%) 患者没有报告任何基础疾病和危险因素。
The percentage of COVID-19 patients with at least one underlying health condition or risk factor was higher among those requiring intensive care unit (ICU) admission (358 of 457, 78%) and those requiring hospitalization without ICU admission (732 of 1,037, 71%) than that among those who were not hospitalized (1,388 of 5,143, 27%).
在需要收入重症监护病房 (ICU) 的患者 (358/457, 78%) 以及需要住院治疗但不需要收入 ICU 的患者 (732/1,037, 71%) 中，存在至少一种基础疾病或危险因素的 COVID-19 患者百分比明显高于不需要住院治疗的患者 (1,388/5,143, 27%)。
The most commonly reported conditions were diabetes mellitus, chronic lung disease, and cardiovascular disease.
最常报告的基础疾病是糖尿病、慢性肺病和心血管病。
These preliminary findings suggest that in the United States, persons with underlying health conditions or other recognized risk factors for severe outcomes from respiratory infections appear to be at a higher risk for severe disease from COVID-19 than are persons without these conditions.
这些初步结果表明，在美国，存在基础疾病以及呼吸道感染严重后果的其他已知危险因素的个体发生重症 COVID-19 的风险似乎高于不存在这些情况的个体。
Data from laboratory-confirmed COVID-19 cases reported to CDC from 50 states, four U.S. territories and affiliated islands, the District of Columbia, and New York City with February 12–March 28, 2020 onset dates were analyzed.
对 50 个州、四处美国领地和附属岛屿、哥伦比亚特区以及纽约市向 CDC 报告的在 2020 年 2 月 12 日至 3 月 28 日发病并经实验室确诊的 COVID-19 病例的数据进行了分析。
Cases among persons repatriated to the United States from Wuhan, China, and the Diamond Princess cruise ship were excluded.
从中国武汉和钻石公主号游轮遣返美国人员中的病例不包括在内。
For cases with missing onset dates, date of onset was estimated by subtracting 4 days (median interval from symptom onset to specimen collection date among cases with known dates in these data) from the earliest specimen collection.
对于缺少发病日期的病例，通过从最早的标本采集日期减去 4 天（这些数据中已知发病日期的病例中从症状发作到标本采集日期的中位时间间隔）来估算发病日期。
Public health departments reported cases to CDC using a standardized case report form that captures information (yes, no, or unknown) on the following conditions and potential risk factors: chronic lung disease (inclusive of asthma, chronic obstructive pulmonary disease [COPD], and emphysema); diabetes mellitus; cardiovascular disease; chronic renal disease; chronic liver disease; immunocompromised condition; neurologic disorder, neurodevelopmental, or intellectual disability; pregnancy; current smoking status; former smoking status; or other chronic disease.
公共卫生部门使用标准化病例报告表向 CDC 报告病例，病例报告表会采集有关以下疾病和潜在危险因素的信息（是、否或不详）：慢性肺病（包括哮喘、慢性阻塞性肺疾病 [COPD] 以及肺气肿）; 糖尿病；心血管病；慢性肾脏病；慢性肝病；免疫功能低下状态；神经系统疾病、神经发育或智力障碍；妊娠；当前吸烟；既往吸烟史；或其他慢性病。
Data reported to CDC are preliminary and can be updated by health departments over time; critical data elements might be missing at the time of initial report; thus, this analysis is descriptive, and no statistical comparisons could be made.
向 CDC 报告的数据为初步数据，卫生部门可以随时更新；初次报告时可能缺少关键数据元素；因此，此次分析为描述性，无法进行统计比较。
The percentages of patients of all ages with underlying health conditions who were not hospitalized, hospitalized without ICU admission, and hospitalized with ICU admission were calculated.
计算了所有年龄段中存在基础疾病的未住院、住院但未收入 ICU 以及住院并收入 ICU 的患者百分比。
Percentages of hospitalizations with and without ICU admission were estimated for persons aged ≥19 years with and without underlying health conditions.
对于年龄 ≥19 岁且有或没有基础疾病的患者，估算了收入和未收入 ICU 的住院百分比。
This part of the analysis was limited to persons aged ≥19 years because of the small sample size of cases in children with reported underlying health conditions (N = 32).
这一部分分析仅限于年龄 ≥19 岁的患者，因为报告存在基础疾病的儿童病例样本量很小 (N = 32)。
To account for missing data among these preliminary reports, ranges were estimated with a lower bound including cases with both known and unknown status for hospitalization with and without ICU admission as the denominator and an upper bound using only cases with known outcome status as the denominator.
为了说明这些初步报告中的缺失数据，使用同时包括已知和未知收入及未收入 ICU 的住院状态的病例作为分母估计范围的下限，仅使用具有已知结局状态的病例作为分母估计范围的上限。
Because of small sample size and missing data on underlying health conditions among COVID-19 patients who died, case-fatality rates for persons with and without underlying conditions were not estimated.
由于样本量较小以及 COVID-19 死亡患者中基础疾病的数据缺失，因此没有估算存在和不存在基础疾病的患者的病死率。
As of March 28, 2020, a total of 122,653 laboratory-confirmed COVID-19 cases (Figure) and 2,112 deaths were reported to CDC.
截至 2020 年 3 月 28 日，总共向 CDC 报告了 122,653 起经实验室确诊的 COVID-19 病例（图）和 2,112 例死亡。
Case report forms were submitted to CDC for 74,439 (60.7%) cases.
已经向 CDC 提交了 74,439 (60.7%) 起病例的病例报告表。
Data on presence or absence of underlying health conditions and other recognized risk factors for severe outcomes from respiratory infections (i.e., smoking and pregnancy) were available for 7,162 (5.8%) patients (Table 1).
7,162 名 (5.8%) 患者的数据包含是否存在基础疾病以及呼吸道感染严重后果的其他已知危险因素（即，吸烟和妊娠）（表 1）。
Approximately one third of these patients (2,692, 37.6%), had at least one underlying condition or risk factor.
这些患者中约有三分之一 (2,692, 37.6%) 具有至少一种基础疾病或危险因素。
Diabetes mellitus (784, 10.9%), chronic lung disease (656, 9.2%), and cardiovascular disease (647, 9.0%) were the most frequently reported conditions among all cases.
在所有病例中，糖尿病 (784, 10.9%)、慢性肺病 (656, 9.2%) 和心血管病 (647, 9.0%) 是最常报告的疾病。
Among 457 ICU admissions and 1,037 non-ICU hospitalizations, 358 (78%) and 732 (71%), respectively occurred among persons with one or more reported underlying health condition.
在 457 名收入 ICU 和 1,037 名未收入 ICU 的住院患者中，分别有 358 名 (78%) 和 732 名 (71%) 报告存在一种或多种基础疾病。
In contrast, 1,388 of 5,143 (27%) COVID-19 patients who were not hospitalized were reported to have at least one underlying health condition.
相比之下，在 5,143 名未住院治疗的 COVID-19 患者中，有 1,388 名 (27%) 报告存在至少一种基础疾病。
Among patients aged ≥19 years, the percentage of non-ICU hospitalizations was higher among those with underlying health conditions (27.3%–29.8%) than among those without underlying health conditions (7.2%–7.8%); the percentage of cases that resulted in an ICU admission was also higher for those with underlying health conditions (13.3%–14.5%) than those without these conditions (2.2%–2.4%) (Table 2).
对于年龄 ≥19 岁的患者，存在基础疾病的患者中的非 ICU 住院百分比 (27.3%–29.8%) 高于不存在基础疾病的患者 (7.2%–7.8%) ；存在基础疾病的患者中的 ICU 住院百分比 (13.3%–14.5%) 也高于不存在基础疾病的患者 (2.2%–2.4%)（表 2）。
Small numbers of COVID-19 patients aged &lt; 19 years were reported to be hospitalized (48) or admitted to an ICU (eight).
年龄 &lt;19 岁的 COVID-19 患者报告住院治疗 (48) 或收入 ICU (8) 的数量较少。
In contrast, 335 patients aged &lt; 19 years were not hospitalized and 1,342 had missing data on hospitalization.
相比之下，335 名年龄 &lt;19 岁的患者没有住院，1,342 名患者缺少住院数据。
Among all COVID-19 patients with complete information on underlying conditions or risk factors, 184 deaths occurred (all among patients aged ≥19 years); 173 deaths (94%) were reported among patients with at least one underlying condition.
在所有具有基础疾病或危险因素完整信息的 COVID-19 患者中，有 184 例死亡（所有死亡患者的年龄均 ≥19 岁）；在具有至少一种基础疾病的患者中报告了 173 例死亡 (94%)。
Among 122,653 U.S. COVID-19 cases reported to CDC as of March 28, 2020, 7,162 (5.8%) patients had data available pertaining to underlying health conditions or potential risk factors; among these patients, higher percentages of patients with underlying conditions were admitted to the hospital and to an ICU than patients without reported underlying conditions.
截至 2020 年 3 月 28 日，在向 CDC 报告的 122,653 名美国 COVID-19 病例中，有 7,162 名 (5.8%) 患者具有与基础疾病或潜在危险因素有关的数据；在这些患者中，有基础疾病的患者住院和收入 ICU 的百分比要高于未报告基础疾病的患者。
These results are consistent with findings from China and Italy, which suggest that patients with underlying health conditions and risk factors, including, but not limited to, diabetes mellitus, hypertension, COPD, coronary artery disease, cerebrovascular disease, chronic renal disease, and smoking, might be at higher risk for severe disease or death from COVID-19.
这些结果与中国以及意大利的发现一致，表明患者如有基础疾病和危险因素，包括但不限于糖尿病、高血压、COPD、冠状动脉疾病、脑血管病、慢性肾脏病和吸烟，则因 COVID-19 导致重症或死亡的风险可能更高。
This analysis was limited by small numbers and missing data because of the burden placed on reporting health departments with rapidly rising case counts, and these findings might change as additional data become available.
这项分析受到数量少和缺失数据的限制，因为迅速增加的病例数对上报卫生部门造成了负担，随着更多数据的获得，这些结果可能会改变。
It is not yet known whether the severity or level of control of underlying health conditions affects the risk for severe disease associated with COVID-19.
目前尚不清楚基础疾病的严重程度或控制水平是否会影响与 COVID-19 相关的重症风险。
Many of these underlying health conditions are common in the United States: based on self-reported 2018 data, the prevalence of diagnosed diabetes among U.S. adults was 10.1%, and the U.S. age-adjusted prevalence of all types of heart disease (excluding hypertension without other heart disease) was 10.6% in 2017.
许多这些基础疾病在美国很常见：根据 2018 年自我报告的数据，美国成年人中诊断为糖尿病的患病率为 10.1%，美国所有类型心脏病（不伴其他心脏病的高血压除外）的年龄调整患病率在 2017 年为 10.6%。
The age-adjusted prevalence of COPD among U.S. adults is 5.9%, and in 2018, the U.S. estimated prevalence of current asthma among persons of all ages was 7.9%.
美国成年人中的年龄调整 COPD 患病率为 5.9%，而在 2018 年，美国所有年龄段人群中的当前哮喘估计患病率为 7.9%。
CDC continues to develop and update resources for persons with underlying health conditions to reduce the risk of acquiring COVID-19.
CDC 继续为存在基础疾病的人们开发和更新资源，以降低感染 COVID-19 的风险。
The estimated higher prevalence of these conditions among those in this early group of U.S. COVID-19 patients and the potentially higher risk for more severe disease from COVID-19 associated with the presence of underlying conditions highlight the importance of COVID-19 prevention in persons with underlying conditions.
美国的这个早期 COVID-19 患者群体中基础疾病的较高估计患病率，以及基础疾病的存在与 COVID-19 可能导致更严重疾病的更高风险之间的相关性，凸显了在具有基础疾病的患者中预防 COVID-19 的重要性。
The findings in this report are subject to at least six limitations.
本报告的结果至少存在六个局限性。