Assessment of global asymptomatic SARS-CoV-2 infection and management practices from China

With ongoing research, it was found that asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was widespread in coronavirus disease 2019 (COVID-19) populations. Studies have confirmed asymptomatic patients with COVID-19 have potential infectivity, and most of the transmission occurred before symptoms appear. Asymptomatic infection rates varied widely in different countries and regions. Identifying the asymptomatic infected persons and cutting off the infection source is an effective way to prevent the spread of this disease. However, asymptomatic patients have hidden clinical symptoms, and screening based only on the clinical symptoms of COVID-19 can easily lead to a missed diagnosis. Therefore, determining asymptomatic infection patients by SARS-CoV-2 nucleic acid testing is the gold standard. A series of prevention and control measures adopted by the Chinese government, especially the “Four Early” policy, have achieved outstanding achievements, which are worth learning from by other countries.     

Antibody profile in symptomatic/asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected Saudi persons

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected persons could be symptomatic or asymptomatic. Asymptomatic and symptomatic patients can transmit SARS-CoV-2. This study aimed to study the humoral immune response in Saudis who are Covid-19 symptomatic and asymptomatic patients. We created three types of enzyme-linked immunosorbant assays (ELISAs) to reveal IgG and IgM antibodies (Abs) against SARS-CoV-2. The developed ELISAs were designed to detect Abs against SARS-CoV-2 N, S and N + S proteins. A number of Covid-19 symptomatic (1 5 3) and asymptomatic (84) RT–PCR-confirmed patient sera were used to evaluate the ELISAs and to determine the IgG and IgM antibody profile in those patients. The sensitivity and specificity of these ELISAs were evaluated using pre-Covid-19 pandemic serum samples. The results revealed the existence of anti-SARS-CoV-2 IgG and IgM Abs in Covid-19 symptomatic and asymptomatic Saudi persons. The use of SARS-CoV-2 N and S proteins in the same ELISA greatly increased the detectability of infection. In conclusion, the Covid-19 symptomatic and asymptomatic Saudi persons demonstrated both IgG and IgM antibody profile with higher titer in symptomatic patients. The use of N + S proteins as antibody capture antigens greatly increased the ELISA sensitivity.     

The seroprevalence of SARS-CoV-2 IgG antibodies among asymptomatic blood donors in Saudi Arabia

BackgroundIn late 2019, cases of severe pneumonia with unidentified etiology began to emerge in Wuhan, China, before progressively spreading first nationally and then globally.The current study sought to investigate the seroprevalence of immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among blood donors in Al-Madinah, Saudi Arabia. To our knowledge, this is the first study in Saudi Arabia to screen blood donors who were not known to be previously infected with SARS-CoV-2.MethodsThis study was a cross-sectional study to assess individuals who donated blood to the central blood bank in Al-Madinah between mid-May and mid-July 2020. An enzyme-linked immunosorbent assay (ELISA) was designed and established to detect antibodies directed against the SARS-CoV-2 spike protein in serum samples. A total of 1,212 healthy blood donors participated in this study. The donors were males and met the requirements for blood donation during the COVID-19 pandemic period in Saudi Arabia.ResultsThe SARS-CoV-2 seroprevalence among blood donors in Al-Madinah was 19.31% (n = 234/1212; 95% confidence interval: 17.12%–21.64%). No statistically significant difference was identified in seropositivity according to age. However, significant differences (p < 0.001) were identified according to ABO blood groups, with those with type A blood presenting the highest rate of seropositivity (29.18%) compared with the other blood groups (12.65% for type B, 16.36% for type AB, and 15.11% for type O).ConclusionA high prevalence of SARS-CoV-2 antibodies was detected among blood donors in Al-Madinah, which indicated a high level of exposure to the virus within the population. This further suggested that as high as one-fifth of the population may have acquired innate immunity against the virus.     

Clinical and immunological features of convalescent pediatric patients infected with the SARS-CoV-2 Omicron variant in Tianjin,China

COVID-19 has spread surprisingly fast worldwide, and new variants continue to emerge. Recently, the World Health Organization acknowledged a new mutant strain “Omicron”, with children were accounting for a growing share of COVID-19 cases compared with other mutant strains. However, the clinical and immunological characteristics of convalescent pediatric patients after Omicron infection were lacking. In this study, we comparatively analyzed the clinical data from pediatric patients with adult patients or healthy children and the effects of SARSCoV-2 vaccine on the clinical and immune characteristics in convalescent pediatric patients. Our results indicated that convalescent pediatric patients had unique clinical and immune characteristics different from those of adult patients or healthy children, and SARS-CoV-2 vaccination significantly affected on the clinical and immune characteristics and the prevention of nucleic acid re-detectable positive (RP) in convalescent patients. Our study further deepens the understanding of the impact of Omicron on the long-term health of pediatric patients and provides a valuable reference for the prevention and treatment of children infected with Omicron.     

Receptor-binding domain of SARS-CoV-2 spike protein efficiently inhibits SARS-CoV-2 infection and attachment to mouse lung

COVID-19, caused by a novel coronavirus, SARS-CoV-2, poses a serious global threat. It was first reported in 2019 in China and has now dramatically spread across the world. It is crucial to develop therapeutics to mitigate severe disease and viral spread. The receptor-binding domains (RBDs) in the spike protein of SARS-CoV and MERS-CoV have shown anti-viral activity in previous reports suggesting that this domain has high potential for development as therapeutics. To evaluate the potential antiviral activity of recombinant SARS-CoV-2 RBD proteins, we determined the RBD residues of SARS-CoV-2 using a homology search with RBD of SARS-CoV. For efficient expression and purification, the signal peptide of spike protein was identified and used to generate constructs expressing recombinant RBD proteins. Highly purified RBD protein fused with the Fc domain of human IgG showed potent anti-viral efficacy, which was better than that of a protein fused with a histidine tag. Intranasally pre-administrated RBD protein also inhibited the attachment of SARS-COV-2 to mouse lungs. These findings indicate that RBD protein could be used for the prevention and treatment of SARS-CoV-2 infection.     

Natural killer cell exhaustion in SARS-CoV-2 infection

At the end of 2019, an outbreak of a severe respiratory disease occurred in Wuhan China, and an increase in cases of unknown pneumonia was alerted. In January 2020, a new coronavirus named SARS-CoV-2 was identified as the cause. The virus spreads primarily through the respiratory tract, and lymphopenia and cytokine storms have been observed in severely ill patients. This suggests the existence of an immune dysregulation as an accompanying event during a serious illness caused by this virus. Natural killer (NK) cells are innate immune responders, critical for virus shedding and immunomodulation. Despite its importance in viral infections, the contribution of NK cells in the fight against SARS-CoV-2 has yet to be deciphered. Different studies in patients with COVID-19 suggest a significant reduction in the number and function of NK cells due to their exhaustion. In this review, we summarize the current understanding of how NK cells respond to SARS-CoV-2 infection.     

Clinical and Genetic Characteristics of Coronaviruses with Particular Emphasis on SARS-CoV-2 Virus

The rapidly spreading Coronavirus Disease 2019 (COVID-19) pandemic has led to a global health crisis and has left a deep mark on society, culture, and the global economy. Despite considerable efforts made to contain the disease, SARS-CoV-2 still poses a threat on a global scale. The current epidemiological situation caused an urgent need to understand the basic mechanisms of the virus transmission and COVID-19 severe course. This review summarizes current knowledge on clinical courses, diagnostics, treatment, and prevention of COVID-19. Moreover, we have included the latest research results on the genetic characterization of SARS-CoV-2 and genetic determinants of susceptibility and severity to infection.     

SARS-CoV-2 infection: The role of cytokines in COVID-19 disease

COVID-19 disease, caused by infection with SARS-CoV-2, is related to a series of physiopathological mechanisms that mobilize a wide variety of biomolecules, mainly immunological in nature. In the most severe cases, the prognosis can be markedly worsened by the hyperproduction of mainly proinflammatory cytokines, such as IL-1, IL-6, IL-12, IFN-γ, and TNF-α, preferentially targeting lung tissue. This study reviews published data on alterations in the expression of different cytokines in patients with COVID-19 who require admission to an intensive care unit. Data on the implication of cytokines in this disease and their effect on outcomes will support the design of more effective approaches to the management of COVID-19.     

Previous infection with SARS-CoV-2 impacts embryo morphokinetics but not clinical outcomes in a time-lapse imaging system

The goal for the present study was to investigate whether previous infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may compromise embryo morphokinetics and implantation. For that, a historical cohort study was performed in a private university-affiliated in vitro fertilization center. The study included 1628 embryos from 88 patients undergoing intracytoplasmic sperm injection (ICSI) cycles. Patients were age-matched in a 1:3 ratio to either a coronavirus disease (COVID) group, including patients with a positive SARS-CoV-2 immunoglobulin test (n = 22 patients, 386 embryos), or a control group, including patients with a negative SARS-CoV-2 immunoglobulin test (n = 66, 1242 embryos). The effect of previous infection with SARS-CoV-2 on morphokinetic events and ICSI outcomes was evaluated. Embryos derived from patients in the COVID group presented longer time to pronuclei appearance and fading, time to form two, three, four and five cells, and time to blastulation. The durations of the third cell cycle and to time to complete synchronous divisions were also significantly increased in the COVID group compared with the control group, whereas known implantation diagnosis score Day 5 ranked significantly lower in the COVID group. No differences were observed between the COVID and control groups on clinical outcomes. In conclusion, patients planning parenthood, who have recovered from COVID-19 infection, must be aware of a possible effect of the infection on embryo development potential.     

Probable Pangolin Origin of SARS-CoV-2 Associated with the COVID-19 Outbreak

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mRNA Vaccines: Possible Tools to Combat SARS-CoV-2

正Coronaviruses are large, enveloped, positive-strand RNA viruses. Several coronaviruses are pathogenic in humans,including severe acute respiratory syndrome coronavirus(SARS-CoV), Middle East respiratory syndrome coronavirus(MERS-CoV) and this novel virus, SARS-CoV-2,     

SARS-CoV-2 infection and oxidative stress: Pathophysiological insight into thrombosis and therapeutic opportunities

The current coronavirus disease 2019 (COVID-19) pandemic has presented unprecedented challenges to global health. Although the majority of COVID-19 patients exhibit mild-to-no symptoms, many patients develop severe disease and need immediate hospitalization, with most severe infections associated with a dysregulated immune response attributed to a cytokine storm. Epidemiological studies suggest that overall COVID-19 severity and morbidity correlate with underlying comorbidities, including diabetes, obesity, cardiovascular diseases, and immunosuppressive conditions. Patients with such comorbidities exhibit elevated levels of reactive oxygen species (ROS) and oxidative stress caused by an increased accumulation of angiotensin II and by activation of the NADPH oxidase pathway. Moreover, accumulating evidence suggests that oxidative stress coupled with the cytokine storm contribute to COVID-19 pathogenesis and immunopathogenesis by causing endotheliitis and endothelial cell dysfunction and by activating the blood clotting cascade that results in blood coagulation and microvascular thrombosis. In this review, we survey the mechanisms of how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces oxidative stress and the consequences of this stress on patient health. We further shed light on aspects of the host immunity that are crucial to prevent the disease during the early phase of infection. A better understanding of the disease pathophysiology as well as preventive measures aimed at lowering ROS levels may pave the way to mitigate SARS-CoV-2-induced complications and decrease mortality.     

The SARS-CoV-2 induced targeted amino acid profiling in patients at hospitalized and convalescent stage

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has induced an ongoing global health crisis. Here we utilized a combination of targeted amino acids (AAs) and clinical biochemical profiling to analyze the plasma of coronavirus disease 2019 (COVID-19) subjects at the hospitalization stage and 1-month post-infection convalescent stage, respectively, to investigate the systematic injury during COVID-19 disease progress. We found the virus-induced inflammatory status and reduced liver synthesis capacity in hospitalized patients, which manifested with increased branched-chain AAs (BCAAs), aromatic AAs (AAAs), one-carbon related metabolites, and decreased methionine. Most of these disturbances during infection recover except for the increased levels of medium-chain acylcarnitines (ACs) in the convalescent subjects, implying the existence of incomplete fatty acids oxidation during recovery periods. Our results suggested that the imbalance of the AA profiling in COVID-19 patients. The majority of disturbed AAs recovered in 1 month. The incomplete fatty acid oxidation products suggested it might take longer time for convalescent patients to get complete recovery.     

新型冠状病毒序列变异时空分析系统的设计与实现

新型冠状病毒肺炎目前已进入全球大流行状态,多个国家出现疫情爆发。美国疾病管制局期刊《新兴传染病》发表的关于新型冠状病毒的最新研究结论显示,新型冠状病毒基本传染数R0的中位数高达5.7,这意味着在未来较长时间内新型冠状病毒可能会在人群中持续传播并发生变异。在这一背景下,如何监视病毒的变异,对于冠状病毒的研究和药物研发具有重要意义。本文基于来自GISAID的病毒基因组序列数据,设计和实现了新型冠状病毒变异时空分析系统。该系统可对来自不同国家和地区的新型冠状病毒序列数进行统计,对病毒序列在不同时间、不同空间内的变异情况进行分析和可视化,同时还支持不同序列之间的差异比对。该系统可为新型冠状病毒肺炎的研究和政府的疾病控制机构的决策提供支持。     

新型冠状病毒亚单位疫苗研究进展及现状*

自新型冠状病毒肺炎在2019年年末暴发以来,如何高效防控疫情一直是紧急的全球公共安全事件。疫苗是有效阻止病毒感染人体、保护高危人群免于疾病快速进展以及遏制疫情进一步扩大的手段之一,其中亚单位疫苗的主要成分为特定的病毒抗原蛋白或多肽,通过加入疫苗佐剂提高抗原的免疫原性。由于机体仅针对重组蛋白表面的特定抗原表位进行识别并产生抗体,因此亚单位疫苗具有较高的保护能力和安全性。通过对目前已上市及处于临床阶段的各类新型冠状病毒亚单位疫苗进行梳理,介绍了各类亚单位疫苗的抗原设计策略和佐剂选择、整体保护能力及研究进展,并对亚单位疫苗的应用及技术优势进行分析,期望能为亚单位疫苗研发及全球疫情防控提供参考。     

Phenotypes and Functions of SARS-CoV-2-Reactive T Cells

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), which is an ongoing pandemic disease. SARS-CoV-2-specific CD4⁺ and CD8⁺ T-cell responses have been detected and characterized not only in COVID-19 patients and convalescents, but also unexposed individuals. Here, we review the phenotypes and functions of SARS-CoV-2-specific T cells in COVID-19 patients and the relationships between SARS-CoV-2-specific T-cell responses and COVID-19 severity. In addition, we describe the phenotypes and functions of SARS-CoV-2-specific memory T cells after recovery from COVID-19 and discuss the presence of SARS-CoV-2-reactive T cells in unexposed individuals and SARS-CoV-2-specific T-cell responses elicited by COVID-19 vaccines. A better understanding of T-cell responses is important for effective control of the current COVID-19 pandemic.