人ACE2转基因小鼠对SARS-CoV的易感性

目的建立敏感的SARS小动物模型。方法通过显微注射技术,将编码SARS-CoV细胞受体的人血管紧张素转换酶(hACE2)基因导入小鼠的基因组中制备了hACE2转基因小鼠,在小鼠ACE2(mACE2)启动子的调控下,hACE2蛋白在转基因小鼠的肺脏、心脏、肾脏和小肠表达。我们观察了野生型和转基因小鼠在SARS冠状病毒接种后病原学和病理学方面的反应。结果在接种后第3天和第7天,病毒能够更有效地在转基因小鼠的肺脏复制,而且转基因小鼠出现更严重的肺损伤。肺组织的损伤包括肺间质充血、出血,单核细胞、淋巴细胞浸润及血浆蛋白的渗出,肺泡上皮细胞增生、脱落,此外,在转基因小鼠的某些器官还发现了血管炎、变性和坏死等病理变化。在转基因小鼠的肺上皮细胞、血管内皮细胞和脑神经细胞检测到病毒抗原。结论转基因小鼠比野生型小鼠对SARS病毒更易感,而且表现出更接近SARS患者的病理变化。     

SARS-CoV-2 variants B.1.351 and P.1 escape from neutralizing antibodies

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新型冠状病毒南非B.1.351变异株的分离与分子特征分析

2020年12月广州市第八人民医院收治了 1例南非输入性COVID-19病例,经检测为SARS-CoV-2核酸阳性的实验室确诊病例.本研究使用Vero-E6细胞,对该病例咽拭子样本进行病毒分离,逐日观察,咽拭子接种的细胞管3d开始出现细胞融合样细胞病变(Cytopathic effect,CPE),5d出现完全CPE后再进行第二代接种,2d出现病变,提取核酸进行鉴定,为SARS-CoV-2阳性.第2代复传的SARS-CoV-2病毒株TCID50测定结果为5.5log TCID50/0.1mL～5.8log TCID50/0.1mL.对分离毒株经采用三代测序成功获得全基因组序列,进化分析结果为与参考毒株Wuhan/Hu-1/2019相比共发生30个碱基的变异、18个氨基酸的突变和18个碱基的缺失,比对结果显示分离到的毒株为SARS-CoV-2南非B.1.351变异株.     

Infection- and vaccine-induced antibody binding and neutralization of the B.1.351 SARS-CoV-2 variant

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Evidence of escape of SARS-CoV-2 variant B.1.351 from natural and vaccine-induced sera

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Structural basis for accommodation of emerging B.1.351 and B.1.1.7 variants by two potent SARS-CoV-2 neutralizing antibodies

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Protective Efficacy of Inactivated Vaccine against SARS-CoV-2 Infection in Mice and Non-Human Primates

Virologica Sinica - The ongoing coronavirus disease 2019 (COVID-19) pandemic caused more than 96 million infections and over 2 million deaths worldwide so far. However, there is no approved vaccine...     

B.1.617.2 (Delta) Variant of SARS-CoV-2: features,transmission and potential strategies

Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a pandemic. With the continuous evolution of the viral genome, SARS-CoV-2 has evolved many variants. B.1.617.2, also called Delta, is one of the most concerned variants. The Delta variant was first reported in India at the end of 2020 but has spread globally, by now, to 135 countries and is not stand still. Delta shared some mutations with other variants, and owned its special mutations on spike proteins, which may be responsible for its strong transmission and increasing virulence. Under these circumstances, a systematic summary of Delta is necessary. This review will focus on the Delta variant. We will describe all the characteristics of Delta (including biological features and clinical characteristics), analyze potential reasons for its strong transmission, and provide potential protective ways for combating Delta.     

Pathogenicity of Helicobacter ganmani in Mice Susceptible and Resistant to Infection with H. hepaticus

Helicobacter spp. are some of the most prevalent bacterial contaminants of laboratory mice. Although abundant data regarding the diseases associated with H. hepaticus infection are available, little is known about the pathogenicity of H. ganmani, which was first isolated in 2001 from the intestines of laboratory mice. The objective of this study was to evaluate the host response to H. ganmani colonization in H. hepaticus disease-resistant C57BL/6 and disease-susceptible A/J and IL10-deficient mice. Mice were inoculated with H. ganmani, H. hepaticus, or Brucella broth. Cecal lesion scores, cecal gene expression, and Helicobacter load were measured at 4 and 90 d after inoculation. At both time points, mice inoculated with H. ganmani had similar or significantly more copies of cecum-associated Helicobacter DNA than did mice inoculated with H. hepaticus. When compared with those of sham-inoculated control mice, cecal lesion scores at 4 and 90 d after inoculation were not significantly greater in H. ganmani-inoculated A/J, C57BL/6, or IL10-deficient mice. Analysis of cecal gene expression demonstrated that H. ganmani infection failed to cause significant elevations of IFNγ in A/J, C57BL/6, or IL10-deficient mice. However, in IL10-deficient mice, H. ganmani infection was associated with a significant increase in the expression of the proinflammatory cytokine IL12/23p40. Although H. ganmani infection in this study failed to induce the typhlitis that is the hallmark of H. hepaticus infection, infection with H. ganmani was associated with alterations in inflammatory cytokines in IL10-deficient mice.Abbreviations: B6, C57BL/6NCr; HPRT, hypoxanthine guanine phosphoribosyl transferase; IL10 KO, B6129P2-IL10^tm1Cgn/JSince the discovery of the link between Helicobacter pylori and chronic gastritis in 1982,¹⁷ Helicobacter spp. in humans and animals have become a field of extensive study. Due to improved detection methods, there has been a rapid expansion in our understanding and ability to detect native Helicobacter spp. in mouse models. Several reports investigating their prevalence in mice housed in research institutions have found Helicobacter spp. to be some of the most common bacterial contaminants of laboratory rodents.^2,3,12,16,23 Helicobacter hepaticus is perhaps the most notorious of the murine helicobacters, by virtue of the early realization of its pathogenicity in adult mice.^8,24 The hallmarks of infection by H. hepaticus are typhlitis, colitis, and hepatitis.¹⁰ In addition, H. hepaticus is commonly used as a microbial trigger in susceptible mouse strains used as models of inflammatory bowel disease.^5,9,19,21,28 In 2001, less than 10 y after H. hepaticus was discovered, H. ganmani was isolated from the intestines of laboratory mice.²⁶ During its initial characterization, 16S rDNA sequence analysis placed H. ganmani phylogenetically closest to H. rodentium, a urease-negative helicobacter that had been previously isolated from mouse intestines.²⁶Despite the reported endemic presence of H. ganmani in many research colonies,^2,3,12 only a few reports to date have attempted to address H. ganmani’s potential pathogenicity.^22,30 One report describes an outbreak of inflammatory bowel-like disease associated with H. ganmani infection in an otherwise Helicobacter-free conventional colony of IL10-deficient mice.²² The findings from another report describe the effect of natural colonization of IL10-deficient mice with H. ganmani, H. hepaticus, or both.³⁰ In that study, 8- to 20-wk-old mice monoinfected with H. ganmani had significantly lower lesion scores than did mice monoinfected with H. hepaticus, suggesting that infection with H. ganmani alone was not sufficient to cause severe typhlocolitis.³⁰ However, by 34 wk of age, clinical typhlocolitis (diarrhea) and grossly enlarged ceca were observed at necropsy in 2 of the 6 mice monoinfected with H. ganmani.³⁰Although these reports of naturally occurring infections have provided a glimpse into H. ganmani’s potential to produce intestinal disease in immunodeficient mice, a controlled study in immunocompetent and immunodeficient mice had not been conducted previously. The objectives of the current study were to evaluate the effect of H. ganmani infection on intestinal disease and to characterize alterations of inflammatory gene expression associated with infection. To this end, we selected A/J and IL10-deficient mice for this study because of their known susceptibility to H. hepaticus-induced typhlocolitis.^{9,13,14,19,21,28} In contrast, although C57BL/6 mice show an initial spike in inflammatory cytokines after H. hepaticus infection, they do not typically develop chronic disease.¹⁹ We did not expect C57BL/6 mice to develop H. hepaticus-induced disease, but we deemed it prudent to characterize the possible effects—through unknown mechanisms—of H. ganmani on this common strain.Previous studies characterizing cecal gene expression during H. hepaticus induced typhlocolitis demonstrated that IFNγ and IL12/23p40 (IL12/23) are key proinflammatory cytokines that drive typhlitis.¹⁹ Expression of these cytokines was increased in H. hepaticus-inoculated A/J mice but not in H. hepaticus-inoculated C57BL/6 mice.¹⁹ In addition, treatment with neutralizing monoclonal antibodies against these cytokines significantly decreased cecal lesion severity, implicating the roles of IFNγ and IL12/23 in modulating the pathogenesis of typhlitis.¹⁹ We hypothesized that characterizing the effect of H. ganmani infection on expression of IFNγ and IL12/23 would uncover aspects of the host response that are not readily apparent by histologic evaluation of cecal tissue alone.To date, our understanding of the potential for H. ganmani to cause intestinal disease has been limited to reports that focused on the evaluation of histologic disease in naturally infected IL10-deficient mice. Despite the reported endemic presence of H. ganmani in many research colonies,^2,3,12 there are no published reports of disease associated with H. ganmani infection in immunocompetent mice. In addition, H. ganmani shares close sequence homology with H. rodentium, which has been found to be nonpathogenic in monoinfected immunodeficient and immunocompetent mice.²⁰ Therefore, we hypothesized that experimental infection with H. ganmani would not produce disease in H. hepaticus-susceptible or -resistant mice.     

Analysis of the docking property of host variants of hACE2 for SARS-CoV-2 in a large cohort

The recent novel coronavirus disease (COVID-19) outbreak, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is threatening global health. However, an understanding of the interaction of SARS-CoV-2 with human cells, including the physical docking property influenced by the host’s genetic diversity, is still lacking. Here, based on germline variants in the UK Biobank covering 502,543 individuals, we revealed the molecular interactions between human angiotensin-converting enzyme 2 (hACE2), which is the representative receptor for SARS-CoV-2 entry, and COVID-19 infection. We identified six nonsense and missense variants of hACE2 from 2585 subjects in the UK Biobank covering 500000 individuals. Using our molecular dynamics simulations, three hACE2 variants from 2585 individuals we selected showed higher levels of binding free energy for docking in the range of 1.44–3.69 kcal/mol. Although there are diverse contributors to SARS-CoV-2 infections, including the mobility of individuals, we analyzed the diagnosis records of individuals with these three variants of hACE2. Our molecular dynamics simulations combined with population-based genomic data provided an atomistic understanding of the interaction between hACE2 and the spike protein of SARS-CoV-2.     

新型冠状病毒实验室检测方法研究进展

世界范围内流行的SARS-CoV-2已造成大批新型冠状病毒肺炎(COVID-19)患者,严重威胁着全人类生命健康.新型冠状病毒肺炎尚没有特效药,也没有疫苗,实验室确诊新型冠状病毒肺炎,隔离传染源,尽早治愈患者对整个疫情防控起着非常重要的作用.目前实验室检测方法有病毒分离培养、实时荧光定量PCR、环介导等温扩增技术、CRISPR/Cas技术、测序技术、基因芯片和抗原抗体检测.本文就上述几种方法做一综述,为确诊COVID-19提供参考.