Abstract Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread throughout the world, leading to large-scale population infection. Angiotensin-converting enzyme 2 (ACE2) is the receptor of both severe acute respiratory syndrome coronavirus (SARS-CoV) and SARS-CoV-2. However, it is still controversial whether vertical transmission exists. In order to investigate the potential risk of SARS-CoV-2 vertical transmission, we explored ACE2 and transmembrane protease serine 2 (TMPRSS2) expression patterns in peri-implantation embryos and the maternal–fetal interface using previously published single-cell transcriptome data. The results show that day 6 (D6) trophectoderm cells (TE) in peri-implantation embryos, as well as syncytiotrophoblast (STB) at 8 weeks of gestation (STB_8W) and extravillous trophoblasts cells (EVT) at 24 weeks of gestation (EVT_24W) in the maternal–fetal interface, strongly co-expressed ACE2 and TMPRSS2, indicating SARS-CoV-2 infection susceptibility. The ACE2 positive-expressing cells in the three cell types mentioned above are found to share common characteristics, which are involved in autophagy and immune-related processes. ACE2 showed no gender bias in post-implantation embryos but showed a significant gender difference in D6_TE, D6 primitive endoderm cells (PE), and ACE2 positive-expressing STBs. These findings indicate that there may be different SARS-CoV-2 infection susceptibilities of D6 embryos of different genders and during the gestation of different genders. Our results reveal potential SARS-CoV-2 infection risks during embryo transfer, peri-implantation embryo development, and gestation.

中文翻译：

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SARS-CoV-2 进入因子：ACE2 和 TMPRSS2 在围着床胚胎和母胎界面中表达

摘要 严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 已在世界范围内传播，导致大规模人群感染。血管紧张素转换酶 2 (ACE2) 是严重急性呼吸系统综合症冠状病毒 (SARS-CoV) 和 SARS-CoV-2 的受体。然而，是否存在垂直传播仍存在争议。为了研究 SARS-CoV-2 垂直传播的潜在风险，我们使用先前发表的单细胞转录组数据探索了 ACE2 和跨膜蛋白酶丝氨酸 2（TMPRSS2）在围着床胚胎和母胎界面中的表达模式。结果表明，在着床周胚胎中第 6 天 (D6) 滋养外胚层细胞 (TE)，以及妊娠 8 周时的合体滋养层细胞 (STB) (STB_8W) 和妊娠 24 周时的绒毛外滋养层细胞 (EVT) (EVT_24W) 在母胎界面，强烈共表达 ACE2 和 TMPRSS2，表明 SARS-CoV- 2 感染易感性。发现上述三种细胞类型中的 ACE2 阳性表达细胞具有共同特征，这些特征涉及自噬和免疫相关过程。ACE2 在植入后胚胎中没有显示出性别偏见，但在 D6_TE、D6 原始内胚层细胞 (PE) 和表达 ACE2 的 STB 中显示出显着的性别差异。这些发现表明，不同性别的D6胚胎和不同性别的妊娠期可能存在不同的SARS-CoV-2感染易感性。