The coronaviruses (CoVs) called the attention of the world for causing outbreaks of severe acute respiratory syndrome (SARS-CoV), in Asia in 2002-03, and respiratory disease in the Middle East (MERS-CoV), in 2012. In December 2019, yet again a new coronavirus (SARS-CoV-2) first identified in Wuhan, China, was associated with a severe respiratory infection, known today as COVID-19. This new virus is highly transmissible, and quickly spread throughout China and 30 additional countries. As result, the World Health Organization (WHO) elevated the status of the COVID-19 outbreak from emergency of international concern to pandemic on March 11, 2020. The impact of COVID-19 on public health and economy fueled a worldwide race to approve therapeutic and prophylactic agents, but so far, there are no specific antiviral drugs or vaccines available. In current scenario, the development of in vitro systems for viral mass production and for testing antiviral and vaccine candidates proves to be an urgent matter. Research groups around the world are strongly focused on this, and the susceptibility of different cell lines to SARS-CoV-2 infection has already been demonstrated by molecular techniques. However, data on the biology of SARS-CoV-2 at the ultrastructural level in these in vitro models is still scarce. In this study, we documented, by transmission electron microscopy and real-time RT-PCR, the infection of Vero-E6 cells with SARS-CoV-2 samples isolated from Brazilian patients. The infected cells presented cytopathic effects and SARS-CoV-2 particles were observed attached to the cell surface and inside cytoplasmic vesicles. The entry of the virus into cells occurred through the endocytic pathway or by fusion of the viral envelope with the cell membrane. Assembled nucleocapsids were verified inside rough endoplasmic reticulum cisterns (RER). Viral maturation seemed to occur by budding of viral particles from the RER into smooth membrane vesicles. Therefore, the susceptibility of Vero-E6 cells to SARS-CoV-2 infection and the viral pathway inside the cells were demonstrated by ultrastructural analysis.

Background In late December, 2019, patients presenting with viral pneumonia due to an unidentified microbial agent were reported in Wuhan, China. A novel coronavirus was subsequently identified as the causative pathogen, provisionally named 2019 novel coronavirus (2019-nCoV). As of Jan 26, 2020, more than 2000 cases of 2019-nCoV infection have been confirmed, most of which involved people living in or visiting Wuhan, and human-to-human transmission has been confirmed. MethodsWe did next-generation sequencing of samples from bronchoalveolar lavage fluid and cultured isolates from nine inpatients, eight of whom had visited the Huanan seafood market in Wuhan. Complete and partial 2019-nCoV genome sequences were obtained from these individuals. Viral contigs were connected using Sanger sequencing to obtain the full-length genomes, with the terminal regions determined by rapid amplification of cDNA ends. Phylogenetic analysis of these 2019-nCoV genomes and those of other coronaviruses was used to determine the evolutionary history of the virus and help infer its likely origin. Homology modelling was done to explore the likely receptor-binding properties of the virus.Findings The ten genome sequences of 2019-nCoV obtained from the nine patients were extremely similar, exhibiting more than 99·98% sequence identity. Notably, 2019-nCoV was closely related (with 88% identity) to two bat-derived severe acute respiratory syndrome (SARS)-like coronaviruses, bat-SL-CoVZC45 and bat-SL-CoVZXC21, collected in 2018 in Zhoushan, eastern China, but were more distant from SARS-CoV (about 79%) and MERS-CoV (about 50%). Phylogenetic analysis revealed that 2019-nCoV fell within the subgenus Sarbecovirus of the genus Betacoronavirus, with a relatively long branch length to its closest relatives bat-SL-CoVZC45 and bat-SL-CoVZXC21, and was genetically distinct from SARS-CoV. Notably, homology modelling revealed that 2019-nCoV had a similar receptor-binding domain structure to that of SARS-CoV, despite amino acid variation at some key residues.Interpretation 2019-nCoV is sufficiently divergent from SARS-CoV to be considered a new human-infecting betacoronavirus. Although our phylogenetic analysis suggests that bats might be the original host of this virus, an animal sold at the seafood market in Wuhan might represent an intermediate host facilitating the emergence of the virus in humans. Importantly, structural analysis suggests that 2019-nCoV might be able to bind to the angiotensinconverting enzyme 2 receptor in humans. The future evolution, adaptation, and spread of this virus warrant urgent investigation.

Objective: To compare the epidemiological and clinical characteristics of con rmed and suspected corona virus disease 2019 (COVID-19) cases via the process of "triage-screening-isolation-transfer" in the hospitals of non-epidemic areas. Methods: The general data, epidemiological history, clinical symptoms, laboratory examination, and chest computed tomography (CT) imaging characteristics of 38 patients with suspected COVID-19, admitted between January 21 and March 5, 2020, were analyzed. Results: According to the results of the novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) ribonucleic acid (RNA) testing, the patients were divided into study group (RNA positive) and control group (RNA negative). Ultimately, 8 cases were RNA-positive and diagnosed as CDVID-19, and 30 cases were negative. Approximately half of the patients in the study group returned to Chongqing from Wuhan; this number was signi cantly larger than that of the control group (P<0.05). The number of subjects in close contact with the con rmed cases with SARS-CoV-2 RNA-positive and the incidence of aggregation was signi cantly larger in the study group than in the control group (both P<0.05). The clinical symptom of the study group was mainly low fever (with or without cough). The patients with decreased white blood cells (WBC) in the study group were signi cantly more than those in the control group (P<0.05). Both group had reduced lymphocytes (Lym) but the number of patients with increased C-reactive protein (CRP) in the study group was signi cantly more than that in the control group (P<0.05). There were different degrees of chest CT abnormalities in both study and control group (P > 0.05). Conclusion: The epidemiological investigations in screening for infectious diseases is crucial. The risk of infection was high from the primary epidemic area and/or in close contact with the con rmed case. The most common form of clustering occurrence was family aggregation. CDVID-19 was mainly characterized by fever and respiratory symptoms, although asymptomatic infection may also occur. Decreased WBC, decreased Lym, and increased CRP are common characteristics but can also be combined with other respiratory tract virus infections. COVID 19 screening by chest CT alone had certain limitations in non-epidemic areas. COVID-19. Consecutively, the Coronaviridae Study Group of the International Committee on Taxonomy of Viruses renamed the virus as SARS-CoV-2, as it was homologous to the 2003 SARS coronavirus (2-5). SARS-CoV-2 has been con rmed to propagate by human-to-human transmission pattern, and the basic reproduction number (R0) is estimated to be 2.2 according to the early epidemiological survey, which is greater than that of SARS and Middle East respiratory syndrome (MERS) (6-9). The average incubation period of COVID-19 is 5-7 days and 14 days is considered as the appropriate medical observation period (6,10,13) .

Highlights d High-alcohol-producing strains of Klebsiella pneumoniae exist in humans d HiAlc Kpn is associated with NAFLD in a human cohort d Transplant of HiAlc Kpn into mice causes NAFLD d Feeding mice glucose led to detectable blood alcohol, suggesting a biomarker for NAFLD