RNA recombination in a coronavirus: recombination between viral genomic RNA and transfected RNA fragments.

Mouse hepatitis virus (MHV), a coronavirus, has been shown to undergo a high frequency of RNA recombination both in tissue culture and in animal infection. So far, RNA recombination has been demonstrated only between genomic RNAs of two coinfecting viruses. To understand the mechanism of RNA recombination and to further explore the potential of RNA recombination, we studied whether recombination could occur between a replicating MHV RNA and transfected RNA fragments. We first used RNA fragments which represented the 5' end of genomic-sense sequences of MHV RNA for transfection. By using polymerase chain reaction amplification with two specific primers, we were able to detect recombinant RNAs which incorporated the transfected fragment into the 5' end of the viral RNA in the infected cells. Surprisingly, even the anti-genomic-sense RNA fragments complementary to the 5' end of MHV genomic RNA could also recombine with the MHV genomic RNAs. This observation suggests that RNA recombination can occur during both positive- and negative-strand RNA synthesis. Furthermore, the recombinant RNAs could be detected in the virion released from the infected cells even after several passages of virus in tissue culture cells, indicating that these recombinant RNAs represented functional virion RNAs. The crossover sites of these recombinants were detected throughout the transfected RNA fragments. However, when an RNA fragment with a nine-nucleotide (CUUUAUAAA) deletion immediately downstream of a pentanucleotide (UCUAA) repeat sequence in the leader RNA was transfected into MHV-infected cells, most of the recombinants between this RNA and the MHV genome contained crossover sites near this pentanucleotide repeat sequence. In contrast, when exogenous RNAs with the intact nine-nucleotide sequence were used in similar experiments, the crossover sites of recombinants in viral genomic RNA could be detected at more-downstream sites. This study demonstrated that recombination can occur between replicating MHV RNAs and RNA fragments which do not replicate, suggesting the potential of RNA recombination for genetic engineering.     

Regulation of cell death during infection by the severe acute respiratory syndrome coronavirus and other coronaviruses

Both apoptosis and necrosis have been observed in cells infected by various coronaviruses, suggesting that the regulation of cell death is important for viral replication and/or pathogenesis. Expeditious research on the severe acute respiratory syndrome (SARS) coronavirus, one of the latest discovered coronaviruses that infect humans, has provided valuable insights into the molecular aspects of cell-death regulation during infection. Apoptosis was observed in vitro, while both apoptosis and necrosis were observed in tissues obtained from SARS patients. Viral proteins that can regulate apoptosis have been identified, and many of these also have the abilities to interfere with cellular functions. Occurrence of cell death in host cells during infection by other coronaviruses, such as the mouse hepatitis virus and transmissible porcine gastroenteritis virus, has also being extensively studied. The diverse cellular responses to infection revealed the complex manner by which coronaviruses affect cellular homeostasis and modulate cell death. As a result of the complex interplay between virus and host, infection of different cell types by the same virus does not necessarily activate the same cell-death pathway. Continuing research will lead to a better understanding of the regulation of cell death during viral infection and the identification of novel antiviral targets.     

RNA recombination of murine coronaviruses: recombination between fusion-positive mouse hepatitis virus A59 and fusion-negative mouse hepatitis virus 2.

It has previously been shown that the murine coronavirus mouse hepatitis virus (MHV) undergoes RNA recombination at a relatively high frequency in both tissue culture and infected animals. Thus far, all of the recombination sites had been localized at the 5' half of the RNA genome. We have now performed a cross between MHV-2, a fusion-negative murine coronavirus, and a temperature-sensitive mutant of the A59 strain of MHV, which is fusion positive at the permissive temperature. By selecting fusion-positive viruses at the nonpermissive temperature, we isolated several recombinants containing multiple crossovers in a single genome. Some of the recombinants became fusion negative during the plaque purification. The fusion ability of the recombinants parallels the presence or absence of the A59 genomic sequences encoding peplomers. Several of the recombinants have crossovers within 3' end genes which encode viral structural proteins, N and E1. These recombination sites were not specifically selected with the selection markers used. This finding, together with results of previous recombination studies, indicates that RNA recombination can occur almost anywhere from the 5' end to the 3' end along the entire genome. The data also show that the replacement of A59 genetic sequences at the 5' end of gene C, which encodes the peplomer protein, with the fusion-negative MHV-2 sequences do not affect the fusion ability of the recombinant viruses. Thus, the crucial determinant for the fusion-inducing capability appears to reside in the more carboxyl portion of the peplomer protein.     

Relationship between selenium status,selenoproteins and COVID-19 and other inflammatory diseases: A critical review

The antioxidant effects of selenium as a component of selenoproteins has been thought to modulate host immunity and viral pathogenesis. Accordingly, the association of low dietary selenium status with inflammatory and immunodeficiency has been reported in the literature; however, the causal role of selenium deficiency in chronic inflammatory diseases and viral infection is still undefined. The COVID-19, characterized by acute respiratory syndrome and caused by the novel coronavirus 2, SARS-CoV-2, has infected millions of individuals worldwide since late 2019. The severity and mortality from COVID-19 have been associated with several factor, including age, sex and selenium deficiency. However, available data on selenium status and COVID-19 are limited, and a possible causative role for selenium deficiency in COVID-19 severity has yet to be fully addressed. In this context, we review the relationship between selenium, selenoproteins, COVID-19, immune and inflammatory responses, viral infection, and aging. Regardless of the role of selenium in immune and inflammatory responses, we emphasize that selenium supplementation should be indicated after a selenium deficiency be detected, particularly, in view of the critical role played by selenoproteins in human health. In addition, the levels of selenium should be monitored after the start of supplementation and discontinued as soon as normal levels are reached. Periodic assessment of selenium levels after supplementation is a critical issue to avoid over production of toxic metabolites of selenide because under normal conditions, selenoproteins attain saturated expression levels that limits their potential deleterious metabolic effects.     

The SARS-like coronaviruses: the role of bats and evolutionary relationships with SARS coronavirus

Bats represent an order of great evolutionary success, with elevated geographical diffusion and species diversity. This order harbors viruses of high variability which have a great possibility of acquiring the capacity of infecting other animals,including humans. Bats are the natural reservoir for several viruses genetically closely related to the SARScoronavirus which is the etiological agent of severe acute respiratory syndrome (SARS), a human epidemic which emerged in China in 2002-2003. In the last few years, it has been discovered that the association between coronaviruses and bats is a worldwide phenomenon, and it has been hypothesised that all mammalian coronaviruses were derived from ancestral viruses residing in bats. This review analyzes the role of bats as a reservoir of zoonotic viruses focusing more extensively on SARS-related coronaviruses and taking into account the role of African and European strains in the evolutionary history of these viruses.     

Immunomodulatory agents for COVID-19 treatment: possible mechanism of action and immunopathology features

Molecular and Cellular Biochemistry - The novel coronavirus pandemic has emerged as one of the significant medical-health challenges of the current century. The World Health Organization has named...     

Understanding the cross-talk between mediators of infertility and COVID-19

COVID-19 is the ongoing health emergency affecting individuals of all ages around the globe. Initially, the infection was reported to affect pulmonary structures. However, recent studies have delineated the impacts of COVID-19 on the reproductive system of both men and women. Hence, the present review aims to shed light on the distribution of SARS-CoV-2 entry factors in various reproductive organs. In addition, impacts of COVID-19 mediators like disrupted renin angiotensin system, oxidative stress, cytokine storm, fever, and the mental stress on reproductive physiology have also been discussed. For the present study, various keywords were used to search literature on PubMed, ScienceDirect, and Google Scholar databases. Articles were screened for relevancy and were studied in detail for qualitative synthesis of the review. Through our literature review, we found a multitude of effects of COVID-19 mediators on reproductive systems. Studies reported expression of receptors like ACE-2, TMPRSS2, and CD147 in the testes, epididymis, prostrate, seminal vesicles, and ovarian follicles. These proteins are known to serve as major SARS-CoV-2 entry factors. The expression of lysosomal cathepsins (CTSB/CTSL) and/ neuropilin-1 (NRP-1) are also evident in the testes, epididymis, seminal vesicles, fallopian tube, cervix, and endometrium. The binding of viral spike protein with ACE-2 was found to alter the renin-angiotensin cascade, which could invite additional infertility problems. Furthermore, COVID-19 mediated cytokine storm, oxidative stress, and elevated body temperature could be detrimental to gametogenesis, steroidogenesis, and reproductive cycles in patients. Finally, social isolation, confinement, and job insecurities have fueled mental stress and frustration that might promote glucocorticoid-mediated subnormal sperm quality in men and higher risk of miscarriage in women. Hence, the influence of COVID-19 on the alteration of reproductive health and fertility is quite apparent.     

Evolutionary history of the closely related group 2 coronaviruses: porcine hemagglutinating encephalomyelitis virus, bovine coronavirus, and human coronavirus OC43

The close genetic and antigenic relatedness among the group 2 coronaviruses human coronavirus OC43 (HCoV-OC43), bovine coronavirus (BCoV), and porcine hemagglutinating encephalomyelitis virus (PHEV) suggests that these three viruses with different host specificities diverged fairly recently. In this study, we determined the complete genomic sequence of PHEV (strain PHEV-VW572), revealing the presence of a truncated group 2-specific ns2 gene in PHEV in comparison to other group 2 coronaviruses. Using a relaxed molecular clock approach, we reconstructed the evolutionary relationships between PHEV, BCoV, and HCoV-OC43 in real-time units, which indicated relatively recent common ancestors for these species-specific coronaviruses.     

From impossible to possible: the lessons from the control of recent COVID-19 outbreaks in China

The COVID-19 pandemic has catastrophically impacted the world. Before the success in vaccination, this virus shows no sign of stop spreading. Nearly all the countries have implemented stringent approaches to slow down the transmission of the virus, but the virus still caused over 2 million deaths and the number is increasing. Therefore, preventing the virus spreading is still necessary to protect most people, especially the ones with pre-conditions. Mainland China has successfully eradicated the COVID-19 virus infection in Wuhan in 2020. After that, several small-scale outbreaks occurred in many cities in China, but none of these COVID-19 virus infections caused the widespread. In this review, we would like to give a detailed presentation of the approaches that were implemented by the China government to suppress the virus spreading by considering the unique characteristics of this virus and the paths of the virus transmission. Both the pros and cons of these strategies will also be analyzed. The experiences and lessons learned during the virus-fighting in China, expectedly, will be a useful source of reference for other regions in overcoming the threat caused by the COVID-19 virus.     

A review of COVID-19: Treatment strategies and CRISPR/Cas9 gene editing technology approaches to the coronavirus disease

The new coronavirus SARS-CoV-2 pandemic has put the world on lockdown for the first time in decades. This has wreaked havoc on the global economy, put additional burden on local and global public health resources, and, most importantly, jeopardised human health. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats, and the CRISPR associated (Cas) protein (CRISPR/Cas) was identified to have structures in E. coli. The most modern of these systems is CRISPR/Cas. Editing the genomes of plants and animals took several years and cost hundreds of thousands of dollars until the CRISPR approach was discovered in 2012. As a result, CRISPR/Cas has piqued the scientific community's attention, particularly for disease diagnosis and treatment, because it is faster, less expensive, and more precise than previous genome editing technologies. Data from gene mutations in specific patients gathered using CRISPR/Cas can aid in the identification of the best treatment strategy for each patient, as well as other research domains such as coronavirus replication in cell culture, such as SARS-CoV2. The implications of the most prevalent driver mutations, on the other hand, are often unknown, making treatment interpretation difficult. For detecting a wide range of target genes, the CRISPR/Cas categories provide highly sensitive and selective tools. Genome-wide association studies are a relatively new strategy to discovering genes involved in human disease when it comes to the next steps in genomic research. Furthermore, CRISPR/Cas provides a method for modifying non-coding portions of the genome, which will help advance whole genome libraries by speeding up the analysis of these poorly defined parts of the genome.     

Incidence and impact of cardiac arrhythmias in coronavirus disease 2019 (COVID-19): A systematic review and meta-analysis

BackgroundStudies have shown that cardiac arrhythmias may occur in up to 44% of patients with severe coronavirus disease 2019 (COVID-19) and has been associated with an increased risk of death. This systematic review and meta-analysis aimed to evaluate the incidence of cardiac arrhythmias in patients with COVID-19 and their implications on patient prognosis.MethodsWe performed a systematic literature search from PubMed, SCOPUS, Europe PMC, Cochrane Central Databases, and Google Scholar + Preprint Servers. The primary endpoint of the study was poor outcomes including mortality, severe COVID-19, and the need for ICU care.ResultsA total of 4 studies including 784 patients were analyzed. The incidence of arrhythmia in patients with COVID-19 was 19% (9–28%; I²: 91.45). Arrhythmia occurred in 48% (38–57%; I²: 48.08) of patients with poor outcome and 6% (1–12%; I²: 85.33%) of patients without poor outcome. Patients with COVID-19 experiencing arrhythmia had an increased risk of poor outcome (RR 7.96 [3.77, 16.81], p < 0.001; I²: 71.1%). The funnel-plot analysis showed an asymmetrical funnel plot with most of the studies on the right side of the effect estimate. The regression-based Egger’s test showed indication of small-study effects (p = 0.001).ConclusionCardiac arrhythmias were significantly associated with an increased risk of poor outcome in COVID-19. Arrhythmias were observed in 19% of patients with COVID-19 and in 48% of patients with COVID-19 and poor outcomes.     

Clinical trials for the treatment of coronavirus disease 2019(COVID-19): A rapid response to urgent need

正Emerging coronavirus disease 2019, known as COVID-19, is caused by the newly identified SARS-CoV-2 virus. Since the outbreak of COVID-19 in December 2019 in Wuhan (China), more than 70 thousand patients were affected. The disease resulted in 1,870 deaths by February 18, 2020,according to the National Health Commission of People′s Republic of China (http://www.nhc.gov.cn). The number of     

Stem cell therapy for COVID-19 and other respiratory diseases: Global trends of clinical trials

Respiratory diseases, including coronavirus disease 2019 and chronic obstructive pulmonary disease (COPD), are leading causes of global fatality. There are no effective and curative treatments, but supportive care only. Cell therapy is a promising therapeutic strategy for refractory and unmanageable pulmonary illnesses, as proved by accumulating preclinical studies. Stem cells consist of totipotent, pluripotent, multipotent, and unipotent cells with the potential to differentiate into cell types requested for repair. Mesenchymal stromal cells, endothelial progenitor cells, peripheral blood stem cells, and lung progenitor cells have been applied to clinical trials. To date, the safety and feasibility of stem cell and extracellular vesicles administration have been confirmed by numerous phase I/II trials in patients with COPD, acute respiratory distress syndrome, bronchial dysplasia, idiopathic pulmonary fibrosis, pulmonary artery hypertension, and silicosis. Five routes and a series of doses have been tested for tolerance and advantages of different regimes. In this review, we systematically summarize the global trends for the cell therapy of common airway and lung diseases registered for clinical trials. The future directions for both new clinical trials and preclinical studies are discussed.     

The COVID-19 pandemic and birth outcomes in 2020: The role of prenatal care and other channels

We use national birth data to assess the associations between the COVID-19 pandemic during 2020 and birth outcomes in Uruguay. Employing interrupted time series difference-in-differences techniques, we find mixed results, with some pregnancies showing increases in the likelihood of very preterm or very-low-weight births, and some others showing decreases in the incidence of moderate prematurity and moderate low birth weight. Adverse outcomes are more likely among women with low education, women with previous children, and with risk factors, such as smoking or being older than 34. We observe improvements in health at birth for children of non-smokers, women younger than 35, and women with no other children. We underscore the role of health care by showing that women in the private sector, who suffered the strongest contraction in face-to-face prenatal care use, experienced more adverse birth outcomes. Our results also suggest that the economic recession and an increased burden of childcare were behind the increases in preterm and very-low-weight births. Because pollution is an unlikely channel for the positive results, we hypothesize that for some pregnancies, the pandemic improved the intrauterine habitat by leading to a quieter and healthier lifestyle.     

新型冠状病毒肺炎对野生动物疫病立法执法与管理的启迪

进入21世纪以来, 中国爆发了SARS与新型冠状病毒肺炎两场重大传染病。研究表明这两场传染病的疫源可能是蝙蝠, 也可能还有其他中间宿主动物, 人们纷纷要求立法禁止食用野生动物。事实上, 国家已经立法禁止食用受法律保护的和非法来源的野生动物, 市场调查也未发现有蝙蝠出售。那么, SARS病毒与新型冠状病毒是如何从野生动物传到人类的? 我们应当从这两场疫病中吸取哪些教训? 除了全面禁止非法食用野生动物外, 笔者建议: (1)完善野生动物疫病立法, 填补立法空缺。修订现有法律关于野生动物疫病自然疫源地建设项目的管理条款。(2)设立常设机构, 覆盖野生动物疫病调查监测、人与野生动物接触界面检疫监管、易感人群免疫、法律与科学知识普及和疾病防治整个流行病环节, 实现野生动物疫病的早预防、早发现、早治疗, 切实保证社会公共卫生安全。(3)建立野生动物疫病的防控机制, 定期鉴别携带病原的野生动物, 加强对蝙蝠的监测, 发布野生动物疫源疫病控制红线, 加强野生动物疫病执法和预防管理。(4)完善动物生产管理、动物产品及其销售市场的检疫程序。改革人们现场宰杀动物、追求食用鲜活动物食品的习惯。     

Comparative efficacy and safety of pharmacological interventions for the treatment of COVID-19: A systematic review and network meta-analysis

BackgroundNumerous clinical trials and observational studies have investigated various pharmacological agents as potential treatment for Coronavirus Disease 2019 (COVID-19), but the results are heterogeneous and sometimes even contradictory to one another, making it difficult for clinicians to determine which treatments are truly effective.Methods and findingsWe carried out a systematic review and network meta-analysis (NMA) to systematically evaluate the comparative efficacy and safety of pharmacological interventions and the level of evidence behind each treatment regimen in different clinical settings. Both published and unpublished randomized controlled trials (RCTs) and confounding-adjusted observational studies which met our predefined eligibility criteria were collected. We included studies investigating the effect of pharmacological management of patients hospitalized for COVID-19 management. Mild patients who do not require hospitalization or have self-limiting disease courses were not eligible for our NMA. A total of 110 studies (40 RCTs and 70 observational studies) were included. PubMed, Google Scholar, MEDLINE, the Cochrane Library, medRxiv, SSRN, WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov were searched from the beginning of 2020 to August 24, 2020. Studies from Asia (41 countries, 37.2%), Europe (28 countries, 25.4%), North America (24 countries, 21.8%), South America (5 countries, 4.5%), and Middle East (6 countries, 5.4%), and additional 6 multinational studies (5.4%) were included in our analyses. The outcomes of interest were mortality, progression to severe disease (severe pneumonia, admission to intensive care unit (ICU), and/or mechanical ventilation), viral clearance rate, QT prolongation, fatal cardiac complications, and noncardiac serious adverse events. Based on RCTs, the risk of progression to severe course and mortality was significantly reduced with corticosteroids (odds ratio (OR) 0.23, 95% confidence interval (CI) 0.06 to 0.86, p = 0.032, and OR 0.78, 95% CI 0.66 to 0.91, p = 0.002, respectively) and remdesivir (OR 0.29, 95% CI 0.17 to 0.50, p < 0.001, and OR 0.62, 95% CI 0.39 to 0.98, p = 0.041, respectively) compared to standard care for moderate to severe COVID-19 patients in non-ICU; corticosteroids were also shown to reduce mortality rate (OR 0.54, 95% CI 0.40 to 0.73, p < 0.001) for critically ill patients in ICU. In analyses including observational studies, interferon-alpha (OR 0.05, 95% CI 0.01 to 0.39, p = 0.004), itolizumab (OR 0.10, 95% CI 0.01 to 0.92, p = 0.042), sofosbuvir plus daclatasvir (OR 0.26, 95% CI 0.07 to 0.88, p = 0.030), anakinra (OR 0.30, 95% CI 0.11 to 0.82, p = 0.019), tocilizumab (OR 0.43, 95% CI 0.30 to 0.60, p < 0.001), and convalescent plasma (OR 0.48, 95% CI 0.24 to 0.96, p = 0.038) were associated with reduced mortality rate in non-ICU setting, while high-dose intravenous immunoglobulin (IVIG) (OR 0.13, 95% CI 0.03 to 0.49, p = 0.003), ivermectin (OR 0.15, 95% CI 0.04 to 0.57, p = 0.005), and tocilizumab (OR 0.62, 95% CI 0.42 to 0.90, p = 0.012) were associated with reduced mortality rate in critically ill patients. Convalescent plasma was the only treatment option that was associated with improved viral clearance rate at 2 weeks compared to standard care (OR 11.39, 95% CI 3.91 to 33.18, p < 0.001). The combination of hydroxychloroquine and azithromycin was shown to be associated with increased QT prolongation incidence (OR 2.01, 95% CI 1.26 to 3.20, p = 0.003) and fatal cardiac complications in cardiac-impaired populations (OR 2.23, 95% CI 1.24 to 4.00, p = 0.007). No drug was significantly associated with increased noncardiac serious adverse events compared to standard care. The quality of evidence of collective outcomes were estimated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework. The major limitation of the present study is the overall low level of evidence that reduces the certainty of recommendations. Besides, the risk of bias (RoB) measured by RoB2 and ROBINS-I framework for individual studies was generally low to moderate. The outcomes deducted from observational studies could not infer causality and can only imply associations. The study protocol is publicly available on PROSPERO (CRD42020186527).ConclusionsIn this NMA, we found that anti-inflammatory agents (corticosteroids, tocilizumab, anakinra, and IVIG), convalescent plasma, and remdesivir were associated with improved outcomes of hospitalized COVID-19 patients. Hydroxychloroquine did not provide clinical benefits while posing cardiac safety risks when combined with azithromycin, especially in the vulnerable population. Only 29% of current evidence on pharmacological management of COVID-19 is supported by moderate or high certainty and can be translated to practice and policy; the remaining 71% are of low or very low certainty and warrant further studies to establish firm conclusions.

In this meta-analysis, Min Seo Kim and colleagues synthesise results from randomized trials and observational studies on COVID-19 treatments.     

No signature of Y chromosomal resemblance between possible descendants of the Cimbri in Denmark and Northern Italy

Two European populations are believed to be related to the ancient Germanic tribe Cimbri: one living in Northern Italy, the other living in Jutland, Denmark. The people called Cimbri are documented in the ancient Roman historical record. Arriving from the far north their movements can be tracked from successive battles with the Romans. The Cimbri finally entered Italy from the northeast and were defeated at Vercellae (present day Vercelli) in 101 BC by Gaius Marius and his professional legions. Classical sources from the first centuries AD relate the homeland of the Cimbri to the coasts around the Elb estuary (northern Germany) or specifically towards the north (Himmerland in northern Jutland). In the alpine parts of Veneto, northeast of the historical battlefield, local traditions dating back to late medieval time, identify a local population as Cimbri living in Terra dei Cimbri. They are considered the descendents of the Germanic combatants that fled the battlefield at Vercelli. As the defeated Cimbri that possibly fled to the mountains of Northern Italy most likely would have been male (warriors), the present study investigated the possible Y chromosomal diversity of the two present populations using microsatellite markers and single nucleotide polymorphisms. While Cimbri from Himmerland resembled their geographical neighbors from Denmark for the Y-chromosome markers, Cimbri from Italy were significantly differentiated both from Cimbri from Himmerland and from Danes. Therefore, we were not able to show any biological relationship for uniparentally transmitted markers.