此前出院患者复阳一事，虽然一直认为应该是因为“事实上没有治好”而非“再次染病”，但缺乏证据，搬运的这篇文章可以说是一个证据支持。

Pathological evidence for residual SARS-CoV-2 in pulmonary tissues of a ready-for-discharge patient

一例可以出院的患者肺组织中残留SARS-CoV-2的病理学证据

因为是OA文献，所以附上原文，译文，这也是一篇“给编辑的信”

【本人无意冒充作者或谋取商业利益】

本文作者在iNature说是卞修武/平秩方/刘新东，这三位是通讯作者，附作者列表截图。

Dear Editor,

SARS-CoV-2, a novel coronavirus and causing COVID-19, has given rise to a worldwide pandemic.1,2 So far, tens of thousands of COVID-19 patients have been clinically cured and discharged, but multiple COVID-19 cases showed SARS-CoV-2 positive again in discharged patients,3 which raises an attention for the discharged patients. Also, there is an urgent need to understand the pathogenesis of SARS-CoV-2 infection. Here, we conducted postmortem pathologic study in a ready-fordischarge COVID-19 patient who succumbed to sudden cardiovascular accident. Pathological examination revealed SARSCoV-2-viruses remaining in pneumocytes and virus-caused pathological changes in the lungs. Our study provided new insights into SARS-CoV-2 pathogenesis and might facilitate the improvement of clinical guideline for virus containment and disease management.

{SARS-COV-2这种导致COVID-19的新型冠状病毒，已经引起了世界范围的大流行。至今，数以万计的COVID-19患者已经临床治愈并出院，但是多例出院患者又复阳，这引起了对出院患者的关注。同时，迫切需要了解SARS-CoV-2感染的机制。这篇文章中，我们对一名死于突发心血管疾病的已经准备出院的COVID-19患者进行了死后病理学研究。病理学研究显示SARS-CoV-2在肺泡壁细胞和病毒导致的肺部病理改变里有残留。我们的研究为SARS-CoV-2的发病机制提供了新的见解，可能有助于完善病毒控制和疾病管理的临床指南。}

A 78-year-old woman was admitted to hospital on January 27, 2020, due to falling-resulted trauma. This patient reported that she had been exposed to a COVID-19 patient on January 25th. Since January 29th, the patient showed pneumonia symptoms (Supplementary information, Fig. S1a). On Feburary 2nd, the patient was confirmed as SARS-CoV-2 positive by nasopharyngeal swab—PCR test followed by treatment (Supplementary information, Fig. S1a). On Feburary 3rd, chest scan by computerized tomography (CT) showed multiple patchy shadows in both lungs, implying pulmonary infection (Supplementary information, Fig. S1b). From Feburary 8th to 10th, three consecutive PCR tests on nasopharyngeal swab samples indicated SARS-CoV-2 negative (Supplementary information, Fig. S1a). From Feburary 11th to 13th, the patient’s condition was significantly improved, and CT examination showed absorption of pulmonary exudation (Supplementary information, Fig. S1a, b). Accordingly, the patient was ready for discharge. On Feburary 14th, however, this patient fell suddenly into fatal condition with cardiac arrest, and died unfortunately. Clinical laboratory test information was summarized in Supplementary information, Table S1, which revealed that the patient had lymphopenia, a frequent symptom for COVID-19 patients.

{ 2020年1月27日，一名78岁的妇女因摔伤入院。这个病人报告说她在1月25日接触了一个COVID-19病人。自1月29日起，患者出现肺炎症状。2月2日，经鼻咽拭子-PCR检测确诊患者为SARS-CoV-2阳性，随后进行治疗。2月3日，胸部电脑断层扫描（CT）显示两肺多处斑片状阴影，提示肺部感染。从2月8日到10日，对鼻咽拭子样本进行了三次连续的PCR检测，结果显示SARS-CoV-2呈阴性。从2月11日到13日，患者的病情明显改善，CT检查显示吸收了肺渗出物。因此，病人准备出院。然而，在2月14日，这个病人突然陷入致命的心脏骤停状态，不幸死亡。临床实验室检测信息汇总在Supplementary information 表S1中，表S1显示患者有淋巴细胞减少，这是COVID-19患者的常见症状。}

Regardless of the negative detection of SARS-CoV-2 virus nucleic acid from nasopharyngeal swabs, we sought to determine whether there were SARS-CoV-2 viruses remaining in the patient. We performed digital PCR on tissue sections from the lung, liver, heart, intestine, and skin, and unexpectedly found positive SARS-CoV-2 virus nucleic acid only in the lung, but not other tissues (Supplementary information, Fig. S2). Consistently, electron microscopic observation showed clear coronavirus particles in both bronchiolar epithelial cells marked by cilia and type II alveolar epithelial cells (type II AE) featured with lamellar body. Thediameters of virus particles were 70–100nm (Fig. 1a, b). Furthermore, we conducted immunohistochemical (IHC) staining by using monoclonal antibody against SARS-CoV-2 nucleocapsid, and confirmed SARS-CoV-2 viruses existed in the lung tissue (Fig. 1c). Neither coronavirus particles nor SARS-CoV-2 nucleocapsid were detected in the liver, heart, intestine, skin, and bone marrow. These results highlight the remaining of SARS-CoV-2 in the lung of discharged COVID-19 patient.

{不论鼻咽拭子对SARS-CoV-2病毒核酸的阴性检测，我们试图确定患者体内是否存在SARS-CoV-2病毒。我们对来自肺，肝，心脏，肠和皮肤的组织切片进行了dPCR，并且意外地仅在肺中发现了阳性SARS-CoV-2病毒核酸，而在其他组织中没有发现。电子显微镜观察一致在有纤毛的细支气管上皮细胞和具有标志性层状体的II型肺泡上皮细胞（II型AE）中发现了清晰的冠状病毒颗粒。病毒颗粒的直径为70-100nm（图1a，b）。此外，我们通过使用针对SARS-CoV-2核衣壳的单克隆抗体进行免疫组织化学（IHC）染色，并确认肺组织中存在SARS-CoV-2病毒（图1c）。在肝脏，心脏，肠，皮肤和骨髓中均未检测到冠状病毒颗粒和SARS-CoV-2核衣壳。这些结果显示了出院的COVID-19患者肺部剩余的SARS-CoV-2。}

Histopathological examination of the samples from pulmonary biopsy showed predominant diffuse alveolar damage, exemplified by the extensive desquamation of proliferative type II AE, exudative monocytes and macrophages. Some of alveolar walls were partially lined by low columnar type II AE and covered by the formation of hyaline membranes in alveolar space. Thickening of alveolar septa with scattered interstitial inflammatory infiltration and hyaline thrombus in microvessels, but no pulmonary edema was found (Fig. 1d–f). There were also chronic respiratory diseaseassociated changes in the lung tissues. To further delineate the cell types of infiltrated immune cells in alveolar space and septa, we performed IHC staining and found that they were predominantly infiltrating CD68+ macrophages, CD20+ B cells, and CD8+ T cells (Fig. 1g). CD4+ T and CD38+ plasma cells were barely detectable (data not shown).

{肺活检样本的组织病理学检查显示了主要弥漫性肺泡损伤，例如增生型II型AE的广泛脱落，单核细胞和巨噬细胞渗出。部分的肺泡壁衬有低柱状II型AE，并被肺泡腔中形成的透明膜所覆盖。肺泡隔膜增厚，微血管中有散在的间质性炎症和透明血栓，但未发现肺水肿（图1d-f）。肺组织也有慢性的呼吸系统的疾病相关的变化。为了进一步描述肺泡腔和隔膜中浸润的免疫细胞的细胞类型，我们进行了IHC染色，发现主要浸润CD68+巨噬细胞，CD20+B细胞和CD8+T细胞（图1g）。几乎检测不到CD4+T和CD38+浆细胞（数据未显示）。}

Pathological features of COVID-19,4 especially in the pulmonary tissues of mild and recovering patients, remain largely unknown. In this study, we conducted postmortem study in an aged patient with mild COVID-19 pneumonia and found pathological changes of the lungs caused by SARS-CoV-2 infection. Histologically, we observed that the patient’s lung was predominated with diffuse alveolar damages, including disrupt of alveolar septa, proliferation and desquamation of type II AE, exudation of fibrin, monocytes and macrophages, and formation of hyaline membrane. These pulmonary pathologic features were consistent with those seen in SARS and Middle Eastern Respiratory Syndrome (MERS),5–9 highlighting that the successful methodology in managing SARS and MERS could be referred to COVID-2019 patients. By using comprehensive means including electron microscopy and IHC staining, we revealed remaining of SARS-CoV-2 in the lung from the ready-for-discharge patient, which raises a possibility that nasopharyngeal swab negative result might not reflect the virus in lung tissue. In addition, our work provided the first pathological evidence for residual virus in the lung for a patient with virus negative by nasopharyngeal swab—PCR test for consecutive three times. Therefore, PCR detection of SARS-CoV2 nucleic acid on broncho-alveolar lavage fluid, extension of quarantine time, and the timely follow-up medical examination on discharged patients, especially aged ones withunderlying diseases, were strongly recommended for discharged patients.

{ COVID-19的病理特征仍然很大程度上未知，尤其是轻度和康复患者的肺组织中的情况。在这项研究中，我们对一名患有轻度COVID-19肺炎的老年患者进行了死后研究，发现了由SARS-CoV-2感染引起的肺部病理变化。在组织学上，我们观察到患者的肺部以弥漫性肺泡损伤为主，包括肺泡隔的破裂，II型AE的增殖和脱落，纤维蛋白，单核细胞和巨噬细胞的渗出以及透明膜的形成。这些肺部病理特征与SARS和中东呼吸综合征（MERS）中所见的一致，提示管理SARS和MERS的成功方法可以被COVID-2019患者参考。通过使用包括电子显微镜和IHC染色在内的综合手段，我们揭示了准备出院患者肺部有剩余的SARS-CoV-2，这提示鼻咽拭子阴性结果可能不会反映肺组织中的病毒。此外，我们的工作为连续三次鼻咽拭子PCR检测病毒阴性的患者提供了肺部残留病毒的第一个病理学证据。因此，强烈建议对出院患者，特别是有潜在疾病的老年患者，对支气管肺泡灌洗液中SARS-CoV2核酸进行PCR检测，延长检疫时间，及时对出院患者，进行随访体检。}

后文是致谢和reference等部分，不搬运，如果有需要可以找我要原文的pdf，不过这篇是OA文献，可以直接搜索得到。

iNature公众号的介绍这篇文献的地址在这里。https://mp.weixin.qq.com/s/X7b9-nD2Tj80h41dOvXVhA

文中提到的dPCR技术，是一种核酸分子绝对定量技术，相比较qRT-PCR更加定量，不过本人的确没有操作过所以并不了解。

IHC是免疫组化染色