Identification of a novel coronavirus in patients with severe acute respiratory syndrome

Glycyrrhizin, an active component of liquorice roots, and replication of SARS-associated coronavirus

The outbreak of SARS warrants the search for antiviral compounds to treat the disease. At present, no specific treatment has been identified for SARS-associated coronavirus infection. We assessed the antiviral potential of ribavirin, 6-azauridine, pyrazofurin, mycophenolic acid, and glycyrrhizin against two clinical isolates of coronavirus (FFM-1 and FFM-2) from patients with SARS admitted to the clinical centre of Frankfurt University, Germany. Of all the compounds, glycyrrhizin was the most active in inhibiting replication of the SARS-associated virus. Our findings suggest that glycyrrhizin should be assessed for treatment of SARS.

Coronavirus main proteinase (3CLpro) structure: basis for design of anti-SARS drugs

A novel coronavirus has been identified as the causative agent of severe acute respiratory syndrome (SARS). The viral main proteinase (Mpro, also called 3CLpro), which controls the activities of the coronavirus replication complex, is an attractive target for therapy. We determined crystal structures for human coronavirus (strain 229E) Mpro and for an inhibitor complex of porcine coronavirus [transmissible gastroenteritis virus (TGEV)] Mpro, and we constructed a homology model for SARS coronavirus (SARS-CoV) Mpro. The structures reveal a remarkable degree of conservation of the substrate-binding sites, which is further supported by recombinant SARS-CoV Mpro-mediated cleavage of a TGEV Mpro substrate. Molecular modeling suggests that available rhinovirus 3Cpro inhibitors may be modified to make them useful for treating SARS.

Advances in clinical diagnosis and treatment of severe acute respiratory syndrome

It has been proved that severe acute respiratory syndrome (SARS) is caused by SARS-associated coronavirus, a novel coronavirus. SARS originated in Guangdong Province, the People's Republic of China at the end of 2002. At present, it has spread to more than 33 countries or regions all over the world and affected 8 360 people and killed 764 by May 31,2003. Identification of the SARS causative agent and development of a diagnostic test are important. Detecting disease in its early stage, understanding its pathways of transmission and implementing specific prevention measures for the disease are dependent upon swift progress. Due to the efforts of the WHO-led network of laboratories testing for SARS, tests for the novel coronavirus have been developed with unprecedented speed. The genome sequence reveals that this coronavirus is only moderately related to other known coronaviruses. WHO established the definitions of suspected and confirmed and probable cases. But the laboratory tests and definitions are limited. Until now, the primary measures included isolation, ribavirin and corticosteroid therapy, mechanical ventilation, etc. Other therapies such as convalescent plasma are being explored. It is necessary to find more effective therapy. There still are many problems to be solved in the course of conquering SARS.

Severe acute respiratory syndrome and its lesions in digestive system

Severe acute respiratory syndrome (SARS) is an infectious atypical pneumonia that has recently been recognized in the patients in 32 countries and regions. This brief review summarizes some of the initial etiologic findings, pathological description, and its lesions of digestive system caused by SARS virus. It is an attempt to draw gastroenterologists and hepatologists' attention to this fatal illness, especially when it manifests itself initially as digestive symptoms.

ICU management of severe acute respiratory syndrome

BACKGROUND

Severe acute respiratory syndrome (SARS) is a contagious viral illness first recognized in late 2002. It has now been documented in 26 countries worldwide, with significant outbreaks in China, Hong Kong, Singapore, and Toronto. Research into identifying the etiological agent, evaluating modes of disease transmission, and treatment options is currently ongoing.

DISCUSSION

The disease can produce a severe bilateral pneumonia, with progressive hypoxemia. Up to 20% of patients require mechanical ventilatory support, with a fatal outcome occurring in about 5% of cases.

CONCLUSIONS

We review the current knowledge about this disease, with particular emphasis on ICU management and infection control precautions to prevent disease transmission.

Control measures for severe acute respiratory syndrome (SARS) in Taiwan

As of April 14, 2003, Taiwan had had 23 probable cases of severe acute respiratory syndrome (SARS), 19 of which were imported. Taiwan isolated all 23 patients in negative-pressure rooms; extensive personal protective equipment was used for healthcare workers and visitors. For the first 6 weeks of the SARS outbreak, recognized spread was limited to one healthcare worker and three household contacts.

[Severe acute respiratory syndrome]

In the Fall of 2002 a report from Guangdong Province in China showed the occurrence of an outbreak of atypical pneumonia. This outbreak rapidly progressed from China to Hong Kong, Singapore, Toronto, and the USA, to more than 25 countries worldwide and almost 3500 cases to date in april 2003. The clinical features associate a fever with mild respiratory symptoms which can progress to a typical acute respiratory distress syndrome requiring intensive care unit admission. Enteric forms with diarrhea were recently described in Hong Kong. The medical community responded very rapidly and united in front of this major health crisis. In a couple weeks, the agent, a new Coronavirus was isolated, therapeutic guidelines were proposed and measures to limit the outbreak diffusion were started worldwide. We summarize here the history of the outbreak, the clinical, laboratory and radiological features of SARS. April 2003 therapeutic guidelines are also reported.

Comparative full-length genome sequence analysis of 14 SARS coronavirus isolates and common mutations associated with putative origins of infection

BACKGROUND

The cause of severe acute respiratory syndrome (SARS) has been identified as a new coronavirus. Whole genome sequence analysis of various isolates might provide an indication of potential strain differences of this new virus. Moreover, mutation analysis will help to develop effective vaccines.

METHODS

We sequenced the entire SARS viral genome of cultured isolates from the index case (SIN2500) presenting in Singapore, from three primary contacts (SIN2774, SIN2748, and SIN2677), and one secondary contact (SIN2679). These sequences were compared with the isolates from Canada (TOR2), Hong Kong (CUHK-W1 and HKU39849), Hanoi (URBANI), Guangzhou (GZ01), and Beijing (BJ01, BJ02, BJ03, BJ04).

FINDINGS

We identified 129 sequence variations among the 14 isolates, with 16 recurrent variant sequences. Common variant sequences at four loci define two distinct genotypes of the SARS virus. One genotype was linked with infections originating in Hotel M in Hong Kong, the second contained isolates from Hong Kong, Guangzhou, and Beijing with no association with Hotel M (p<0.0001). Moreover, other common sequence variants further distinguished the geographical origins of the isolates, especially between Singapore and Beijing.

INTERPRETATION

Despite the recent onset of the SARS epidemic, genetic signatures are emerging that partition the worldwide SARS viral isolates into groups on the basis of contact source history and geography. These signatures can be used to trace sources of infection. In addition, a common variant associated with a non-conservative aminoacid change in the S1 region of the spike protein, suggests that immunological pressures might be starting to influence the evolution of the SARS virus in human populations.

A multicentre collaboration to investigate the cause of severe acute respiratory syndrome

Severe acute respiratory syndrome is a new disease in human beings, first recognised in late February, 2003, in Hanoi, Vietnam. The severity of the disease, combined with its rapid spread along international air-travel routes, prompted WHO to set up a network of scientists from 11 laboratories around the world to try to identify the causal agent and develop a diagnostic test. The network unites laboratories with different methods and capacities to rapidly fulfil all postulates for establishing a virus as the cause of a disease. Results are shared in real time via a secure website, on which microscopy pictures, protocols for testing, and PCR primer sequences are also posted. Findings are discussed in daily teleconferences. Progress is further facilitated through sharing between laboratories of samples and test materials. The network has identified a new coronavirus, consistently detected in samples of SARS patients from several countries, and conclusively named it as the causative agent of SARS; the strain is unlike any other known member of the genus Coronavirus. Three diagnostic tests are now available, but all have limitations.

Prophylactic and Therapeutic Effects of Small Interfering Rna Targeting Sars-Coronavirus

Objectives

To identify and characterize the siRNA duplexes that are effective for inhibition of SARS-CoV infection and replication in the non-human primate cells. This in vitro study will serve as the foundation for development of novel anti-SARS therapeutics.

Methods

48 siRNA sequences were designed for targeting regions throughout entire SARS-CoV genome RNA including open-reading frames for several key proteins. Chemically synthesized siRNA duplexes were transfected into foetal rhesus kidney (FRhK-4) cells prior to or after SARS-CoV infection. The inhibitory effects of the siRNAs were evaluated for reductions of intracellular viral genome copy number and viral titres in the cell culture medium measured by Q-RT-PCR and CPE-based titration, respectively. Four siRNA duplexes were found to achieve potent inhibition of SARS-CoV infection and replication. A prolonged prophylactic effect of siRNA duplexes with up to 90% inhibition that lasted for at least 72 h was observed. Combination of active siRNA duplexes targeting different regions of the viral genome resulted in therapeutic activity of up to 80% inhibition.

Conclusion

Chemically synthesized siRNA duplexes targeting SARS-CoV genomic RNA are potent agents for inhibition of the viral infection and replication. The location effects of siRNAs were revealed at both genome sequence and open-reading frame levels. The rapid development of siRNA-based SARS-CoV inhibitors marked a novel approach for combating newly emergent infectious diseases.

Probing the Structure of the Sars Coronavirus Using Scanning Electron Microscopy

A novel coronavirus, SARS-CoV, has been confirmed to be the aetiological agent of SARS. Transmission electron microscope (TEM) images played an important role in initial identification of the pathogen. In order to obtain greater morphological detail of SARS-CoV than could be obtained by TEM, we used ultra-high resolution scanning electron microscopy (SEM) to image the virus particles. We show here the three-dimensional appearance of SARS-CoV. Enhanced detail of the ultrastructure reveals the trimeric structure of the 10–20 nm spikes on the virion surface. These results contribute to characterization of the SARS agent and development of new antiviral strategies.

A complete sequence and comparative analysis of a SARS-associated virus (Isolate BJ01)

The genome sequence of the Severe Acute Respiratory Syndrome (SARS)-associated virus provides essential information for the identification of pathogen(s), exploration of etiology and evolution, interpretation of transmission and pathogenesis, development of diagnostics, prevention by future vaccination, and treatment by developing new drugs. We report the complete genome sequence and comparative analysis of an isolate (BJ01) of the coronavirus that has been recognized as a pathogen for SARS. The genome is 29725 nt in size and has 11 ORFs (Open Reading Frames). It is composed of a stable region encoding an RNA-dependent RNA polymerase (composed of 2 ORFs) and a variable region representing 4 CDSs (coding sequences) for viral structural genes (the S, E, M, N proteins) and 5 PUPs (putative uncharacterized proteins). Its gene order is identical to that of other known coronaviruses. The sequence alignment with all known RNA viruses places this virus as a member in the family of Coronaviridae. Thirty putative substitutions have been identified by comparative analysis of the 5 SARS-associated virus genome sequences in GenBank. Fifteen of them lead to possible amino acid changes (non-synonymous mutations) in the proteins. Three amino acid changes, with predicted alteration of physical and chemical features, have been detected in the S protein that is postulated to be involved in the immunoreactions between the virus and its host. Two amino acid changes have been detected in the M protein, which could be related to viral envelope formation. Phylogenetic analysis suggests the possibility of non-human origin of the SARS-associated viruses but provides no evidence that they are man-made. Further efforts should focus on identifying the etiology of the SARS-associated virus and ruling out conclusively the existence of other possible SARS-related pathogen(s).

SARS: what have we learned?

It's less than four months since the World Health Organization issued global warnings about a mysterious and deadly form of pneumonia. Nature's reporters pose key questions about the outbreak, and assess our preparedness to deal with future viral threats.

Bioinformatical study on the proteomics and evolution of SARS-CoV

A novel coronavirus has been identified as the causative agent of the severe acute respiratory syndrome (SARS). For all the SARS-CoV associated proteins derivated from the SARS-CoV genome, the physiochemical properties such as the molecular weight, isoelectric point and extinction coefficient of each protein were calculated. The transmembrane segments and subcellular localization (SubLocation) prediction and conserved protein motifs search against database were employed to analyze the function of SARS-CoV proteins. Also, the homology protein sequence alignment and evolutionary distance matrix calculation between SARS-CoV associated proteins and the corresponding proteins of other coronaviruses were employed to identify the classification and phylogenetic relationship between SARS-CoV and other coronaviruses. The results showed that SARS-CoV is a novel coronavirus which is different from any of the three previously known groups of coronviruses, but it is closer to Bo-CoV and MHV than to other coronaviruses. This study is in aid of experimental determination of SARS-CoV proteomics and the development of antiviral vaccine.

Reovirus, isolated from SARS patients

Beijing has been severely affected by SARS, and SARS-associated coronavirus has been confirmed as its cause. However, clinical and experimental evidence implicates the possibility of co-infection. In this report, reovirus was isolated from throat swabs of SARS patients, including the first case in Beijing and her mother. Identification with the electron microscopy revealed the characteristic features of reovirus. 24 of 38 samples from other SARS cases were found to have serologic responses to the reovirus. Primers designed for reovirus have amplified several fragments of DNA, one of which was sequenced (S2 gene fragment), which indicates it as a unique reovirus (orthoreovirus). Preliminary animal experiment showed that inoculation of the reovirus in mice caused death with atypical pneumonia. Nevertheless, the association of reovirus with SARS outbreak requires to be further investigated.