Characterizing 56 complete SARS-CoV S-gene sequences from Hong Kong

Evolution, Interspecies Transmission, and Zoonotic Significance of Animal Coronaviruses

Coronaviruses are single-stranded RNA viruses that affect humans and a wide variety of animal species, including livestock, wild animals, birds, and pets. These viruses have an affinity for different tissues, such as those of the respiratory and gastrointestinal tract of most mammals and birds and the hepatic and nervous tissues of rodents and porcine. As coronaviruses target different host cell receptors and show divergence in the sequences and motifs of their structural and accessory proteins, they are classified into groups, which may explain the evolutionary relationship between them. The interspecies transmission, zoonotic potential, and ability to mutate at a higher rate and emerge into variants of concern highlight their importance in the medical and veterinary fields. The contribution of various factors that result in their evolution will provide better insight and may help to understand the complexity of coronaviruses in the face of pandemics. In this review, important aspects of coronaviruses infecting livestock, birds, and pets, in particular, their structure and genome organization having a bearing on evolutionary and zoonotic outcomes, have been discussed.

The use of knowledge management tools in viroinformatics. Example study of a highly conserved sequence motif in Nsp3 of SARS-CoV-2 as a therapeutic target

Knowledge management tools that assist in systematic review and exploration of scientific knowledge generally are of obvious potential importance in evidence based medicine in general, but also to the design of therapeutics based on the protein subsequences and fold motifs of virus proteins as considered here. Rapid access to bundles (clusters) of related elements of knowledge gathered from diverse sources on the Internet and from growing knowledge repositories seem particularly helpful when exploring less obvious therapeutic targets in viruses (for which knowledge new to the researcher is important), and when using the following concept. Subsequences of amino acid residue sequences of proteins that are conserved across strains and species are (a) more likely to be important targets and (b) less likely to exhibit escape mutations that would make them resistant to vaccines and therapeutic agents. However, the terms "conserved" and even "highly conserved" used by authors are matters of degree, depending on how distant from SARS-CoV-2 they wished to go in comparing other sequences. The binding site to the human ACE2 protein as virus receptor and human antibody CR3022 binding site on the spike glycoprotein are rather variable by the criteria used in the present and preceding studies. To look for more strongly conserved targets, open reading frames of SARS-CoV-2 were examined for extremely highly conserved regions, meaning recognizable across many viruses and organisms. Most prominent is a motif found in SARS-CoV-2 non-structural protein 3 (Nsp3). It relates to a fold called type called the macro domain and has remarkably wide distribution across organisms including humans with significant homologies involving three especially conserved subsequences (a) VVVNAANVYLKHGGGVAGALNK, (b) LHVVGPNVNKG, and (c) PLLSAGIFG. Careful study of the variations of these and of the more variable sequences between and around them might provide a finer "scalpel" to ensure inhibition of a vital function of the virus without impairing the functions of related host macro domains.

Molecular Testing in Emerging Infectious Diseases

It was widely believed in the late 1960s that infectious diseases had been conquered by vaccines and antibiotics and humans were no longer under threat by microbial pathogens. Yet, since that time more than 60 pathogens have been discovered that can cause serious emerging infectious diseases. Molecular methods have played critical roles in the discovery, monitoring, and clinical diagnostics of emerging pathogens. In this chapter, we present well-recognized emerging pathogens. We provide examples of the utility of molecular assays in research and clinical care of emerging infectious diseases. We also discuss some theoretical and practical limitations of molecular tests and the future prospects of expanding molecular diagnostics for emerging pathogens based on new advances of knowledge and technologies.

Evolution of SARS Coronavirus and the Relevance of Modern Molecular Epidemiology

The severe acute respiratory syndrome (SARS) is the first major zoonotic infectious disease of the 21st Century. The disease, originally termed “atypical pneumonia,” was first recognized in November 2002 in Guangdong Province, China, which spread rapidly to 26 countries within 5 months and eventually led to 8096 human infection cases and 774 deaths. A previously unrecognized coronavirus, named SARS coronavirus (SARS-CoV), was later identified as the causative agent of SARS. Subsequent investigation indicated that the source of the human infections originated most likely from infected wildlife animals traded in the live animal markets, with masked palm civets considered the most prominent and important carrier. Large-scale culling of civets appeared to be effective in preventing further outbreaks in the region. Subsequent epidemiological studies showed that civets are intermediate host of SARS-CoV and bats are the likely natural reservoir of SARS-CoV and a large number of SARS-like coronaviruses (SL-CoVs). Detailed analysis of the massive SARS-CoV genomic sequence data indicated that SARS-CoV experienced a strong selection pressure during different outbreak phases in humans as well as interspecies transmission from animals to humans. The spike glycoprotein (S) of SARS-CoV plays a key role in virus–host interaction and hence is a key determinant of interspecies transmission. It has been shown that minor changes of amino acid (aa) residues in the S protein could lead to dramatic changes in virus susceptibility in animal and human hosts. This chapter focuses on the genetics and evolution of SARS-CoVs and SL-CoVs in humans, civets, and bats. The events of SARS outbreaks and the accompanying response activities highlight the importance of modern molecular epidemiology in disease investigation and the urgent need to broaden the screening and investigation of unknown viruses in wildlife animals.

Phages bearing affinity peptides to severe acute respiratory syndromes-associated coronavirus differentiate this virus from other viruses

BACKGROUND

Transmission of SARS-associated coronavirus (SARS-CoV) is now well controlled, nevertheless, it is important to develop effective methods to identify this virus from other pathogens.

OBJECTIVES

The purpose of this study was to identify potential ligands and develop a novel diagnostic test to SARS-CoV using phage display technology.

STUDY DESIGN

The SARS-CoV spike 1 (S1) protein containing the receptor binding region (RBD) was used as an immobilized target followed by incubation with a 12-mer phage display random peptide library. After four rounds of biopanning, 10 monoclonal phages with specific binding activity to the S1-RBD protein were obtained and subjected to binding and diagnostic assays.

RESULTS

DNA sequencing showed that two phage displayed peptides HHKTWHPPVMHL (phage-H) and SQWHPRSASYPM (phage-S) that were specific ligands to the S1 protein. Moreover, the selected phage-H and phage-S were capable of differentiating SARS-CoV from other coronaviruses in indirect enzyme-linked immunosorbent assays.

CONCLUSION

The peptides identified in this study are useful reagents for detection of SARS-CoV.

Evolution of SARS Coronavirus and the Relevance of Modern Molecular Epidemiology

This chapter discusses the evolution of severe acute respiratory syndrome (SARS) coronavirus and the relevance of modern molecular epidemiology. The first case was reported in China in November 2002 and led to a disastrous worldwide pandemic. An international SARS network was established by WHO to rapidly identify the causative agent. In March 2003, the SARS coronavirus was identified. The majority of the early cases were limited to the Guangdong province of China, which have a unique dietary tradition favoring freshly slaughtered game meat; therefore, studies were conducted in those markets for evidence of SARS-CoV. Antibodies against SARS-CoV were detected in masked palm civets. By using serological and PCR surveillance, it was discovered that SARS-like CoV or SL-CoVs were present in different horseshoe bats in the genus Rhinolophus and that they are the likely natural reservoir hosts of bat SL-CoVs. There are more than 60 different horseshoe species around the world, and one or more of them may serve as the natural reservoir of SARS-CoV and/or its progenitor virus(es). It is therefore likely that another outbreak could occur on a similar scale as that of the SARS-CoV outbreaks but our response to a future outbreak caused by any bat-borne coronavirus will be much more effective. SARS is an example demonstrating the evolution of an animal virus into a human pathogen responsible for one of the most severe global pandemic. It is paramount that from now we include active surveillance of wild animals as part of an integrated infectious disease prevention and control strategy.

Use of phylogenetics in the molecular epidemiology and evolutionary studies of viral infections

Since DNA sequencing techniques first became available almost 30 years ago, the amount of nucleic acid sequence data has increased enormously. Phylogenetics, which is widely applied to compare and analyze such data, is particularly useful for the analysis of genes from rapidly evolving viruses. It has been used extensively to describe the molecular epidemiology and transmission of the human immunodeficiency virus (HIV), the origins and subsequent evolution of the severe acute respiratory syndrome (SARS)-associated coronavirus (SCoV), and, more recently, the evolving epidemiology of avian influenza as well as seasonal and pandemic human influenza viruses. Recent advances in phylogenetic methods can infer more in-depth information about the patterns of virus emergence, adding to the conventional approaches in viral epidemiology. Examples of this information include estimations (with confidence limits) of the actual time of the origin of a new viral strain or its emergence in a new species, viral recombination and reassortment events, the rate of population size change in a viral epidemic, and how the virus spreads and evolves within a specific population and geographical region. Such sequence-derived information obtained from the phylogenetic tree can assist in the design and implementation of public health and therapeutic interventions. However, application of many of these advanced phylogenetic methods are currently limited to specialized phylogeneticists and statisticians, mainly because of their mathematical basis and their dependence on the use of a large number of computer programs. This review attempts to bridge this gap by presenting conceptual, technical, and practical aspects of applying phylogenetic methods in studies of influenza, HIV, and SCoV. It aims to provide, with minimal mathematics and statistics, a practical overview of how phylogenetic methods can be incorporated into virological studies by clinical and laboratory specialists.

Phylogenetic perspectives on the epidemiology and origins of SARS and SARS-like coronaviruses

Severe Acute Respiratory Syndrome (SARS) is a respiratory disease caused by a zoonotic coronavirus (CoV) named SARS-CoV (SCoV), which rapidly swept the globe after its emergence in rural China during late 2002. The origins of SCoV have been mysterious and controversial, until the recent discovery of SARS-like CoV (SLCoV) in bats and the proposal of bats as the natural reservior of the Coronaviridae family. In this article, we focused on discussing how phylogenetics contributed to our understanding towards the emergence and transmission of SCoV. We first reviewed the epidemiology of SCoV from a phylogenetic perspective and discussed the controversies over its phylogenetic origins. Then, we summarized the phylogenetic findings in relation to its zoonotic origins and the proposed inter-species viral transmission events. Finally, we also discussed how the discoveries of SCoV and SLCoV expanded our knowledge on the evolution of the Coronaviridae family as well as its implications on the possible future re-emergence of SCoV.