Molecular diagnosis of severe acute respiratory syndrome: the state of the art

Diagnostic Techniques for COVID-19: A Mini-review of Early Diagnostic Methods

The outbreak of severe pneumonia at the end of 2019 was proved to be caused by the SARS-CoV-2 virus spreading out the world. And COVID-19 spread rapidly through a terrible transmission way by human-to-human, which led to many suspected cases waiting to be diagnosed and huge daily samples needed to be tested by an effective and rapid detection method. With an increasing number of COVID-19 infections, medical pressure is severe. Therefore, more efficient and accurate diagnosis methods were keen urgently established. In this review, we summarized several methods that can rapidly and sensitively identify COVID-19; some of them are widely used as the diagnostic techniques for SARS-CoV-2 in various countries, some diagnostic technologies refer to SARS (Severe Acute Respiratory Syndrome) or/and MERS (Middle East Respiratory Syndrome) detection, which may provide potential diagnosis ideas.

Coronavirus Detection in the Clinical Microbiology Laboratory: Are We Ready for Identifying and Diagnosing a Novel Virus?

Endemic species of coronavirus (HCoV-OC43, HCoV-229E, HCoV-NL63, and HCoV-HKU1) are frequent causes of upper respiratory tract infections. Three highly pathogenic coronaviruses have been associated with outbreaks and epidemics and have challenged clinical microbiology laboratories to quickly develop assays for diagnosis. Their initial characterization was achieved by molecular methods. With the great advance in metagenomic whole-genome sequencing directly from clinical specimens, diagnosis of novel coronaviruses could be quickly implemented into the workflow of managing cases of pneumonia of unknown cause, which will markedly affect the time of the initial characterization and accelerate the initiation of outbreak control measures.

Laboratory diagnosis of emerging human coronavirus infections - the state of the art

The three unprecedented outbreaks of emerging human coronavirus (HCoV) infections at the beginning of the twenty-first century have highlighted the necessity for readily available, accurate and fast diagnostic testing methods. The laboratory diagnostic methods for human coronavirus infections have evolved substantially, with the development of novel assays as well as the availability of updated tests for emerging ones. Newer laboratory methods are fast, highly sensitive and specific, and are gradually replacing the conventional gold standards. This presentation reviews the current laboratory methods available for testing coronaviruses by focusing on the coronavirus disease 2019 (COVID-19) outbreak going on in Wuhan. Viral pneumonias typically do not result in the production of purulent sputum. Thus, a nasopharyngeal swab is usually the collection method used to obtain a specimen for testing. Nasopharyngeal specimens may miss some infections; a deeper specimen may need to be obtained by bronchoscopy. Alternatively, repeated testing can be used because over time, the likelihood of the SARS-CoV-2 being present in the nasopharynx increases. Several integrated, random-access, point-of-care molecular devices are currently under development for fast and accurate diagnosis of SARS-CoV-2 infections. These assays are simple, fast and safe and can be used in the local hospitals and clinics bearing the burden of identifying and treating patients.

Laboratory diagnosis of novel corona virus (2019-nCoV)-present and the future

Background

In December 2019 a novel coronavirus SARS-CoV-2 emerged in the Hunan seafood market in Wuhan, China, and soon became a global health problem. Since its outbreak, SARS-CoV-2 has had a major impact on clinical diagnostic laboratories. The scientific community has quickly risen to the occasion and reports of new developments have arrived at an unprecedented scale. At present, there is a growing list of over 400 SARC-CoV-2 diagnostic tests either in development or approved for clinical use. This presentation reviews the current laboratory methods available for testing COVID- 19 in microbiology laboratories and also provides an insight into the future diagnostics approaches.

Methods

Proper respiratory specimen collected at the appropriate time and from the right anatomical site is critical in the accurate and timely diagnosis of SARSCoV2. While oropharyngeal and nasopharyngeal swabs are recommended for the detection of early infection, other lower respiratory tract specimens like the sputum and bronchoalveolar lavage are used for late detection and monitoring of patients with severe COVID-19 pneumonia.

Results and Conclusion

Real-time RT-PCR based molecular assay remains the test of choice for the etiological diagnosis of SARS-CoV-2 while serological tests are being introduced as supplementary tools. Finally, there is an urgent need for scaling up the diagnostic capacity by the introduction of reliable and accurate point-of-care tests which will assist in effective control of this outbreak. These assays can be used in the local hospitals and clinics bearing the burden of identifying and treating patients.

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At present, there is a growing list of over 400 SARC-CoV-2 diagnostic tests either in development or approved for clinical use.

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Real-time RT-PCR based molecular assay remains the test of choice for the etiological diagnosis of SARS-CoV-2.

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Oropharyngeal and nasopharyngeal swabs are recommended for the detection of early infection.

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Lower respiratory tract specimens can be used for late detection and monitoring of patients with severe COVID-19 pneumonia.

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There is an urgent need for scaling up the diagnostic capacity by the introduction of reliable POC tests.

The New Coronavirus (SARS-CoV-2): A Comprehensive Review on Immunity and the Application of Bioinformatics and Molecular Modeling to the Discovery of Potential Anti-SARS-CoV-2 Agents

On March 11, 2020, the World Health Organization (WHO) officially declared the outbreak caused by the new coronavirus (SARS-CoV-2) a pandemic. The rapid spread of the disease surprised the scientific and medical community. Based on the latest reports, news, and scientific articles published, there is no doubt that the coronavirus has overloaded health systems globally. Practical actions against the recent emergence and rapid expansion of the SARS-CoV-2 require the development and use of tools for discovering new molecular anti-SARS-CoV-2 targets. Thus, this review presents bioinformatics and molecular modeling strategies that aim to assist in the discovery of potential anti-SARS-CoV-2 agents. Besides, we reviewed the relationship between SARS-CoV-2 and innate immunity, since understanding the structures involved in this infection can contribute to the development of new therapeutic targets. Bioinformatics is a technology that assists researchers in coping with diseases by investigating genetic sequencing and seeking structural models of potential molecular targets present in SARS-CoV2. The details provided in this review provide future points of consideration in the field of virology and medical sciences that will contribute to clarifying potential therapeutic targets for anti-SARS-CoV-2 and for understanding the molecular mechanisms responsible for the pathogenesis and virulence of SARS-CoV-2.

The diagnosis of SARS-CoV2 pneumonia: A review of laboratory and radiological testing results

The rapid emergence of coronavirus disease 2019 (COVID‐19) has necessitated the implementation of diverse pandemic control strategies throughout the world. To effectively control the spread of this disease, it is essential that it be diagnosed at an early stage so that patients can be reliably quarantined such that disease spread will be slowed. At present, the diagnosis of this infectious form of coronavirus pneumonia is largely dependent upon a combination of laboratory testing and imaging analyses of variable diagnostic efficacy. In the present report, we reviewed prior literature pertaining to the diagnosis of different forms of pneumonia caused by coronaviruses (severe acute respiratory syndrome [SARS], Middle East respiratory syndrome, and SARS‐CoV‐2) and assessed two different potential diagnostic approaches. We ultimately found that computed tomography was associated with a higher rate of diagnostic accuracy than was a real‐time quantitative polymerase chain reaction‐based approach (P = .0041), and chest radiography (P = .0100). Even so, it is important that clinicians utilize a combination of laboratory and radiological testing where possible to ensure that this virus is reliably and quickly detected such that it may be treated and patients may be isolated in a timely fashion, thereby effectively curbing the further progression of this pandemic.

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CT scan could be a better diagnosis method for COVID‐19 than RT‐PCR (P = .0041).

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The diagnosis rate of CT scan is higher than chest radiography (P = .0100).

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Combination diagnosis should be the main approach for disease control.

Layer-By-Layer Nanocoating of Antiviral Polysaccharides on Surfaces to Prevent Coronavirus Infections

In 2020, the world is being ravaged by the coronavirus, SARS-CoV-2, which causes a severe respiratory disease, Covid-19. Hundreds of thousands of people have succumbed to the disease. Efforts at curing the disease are aimed at finding a vaccine and/or developing antiviral drugs. Despite these efforts, the WHO warned that the virus might never be eradicated. Countries around the world have instated non-pharmaceutical interventions such as social distancing and wearing of masks in public to curb the spreading of the disease. Antiviral polysaccharides provide the ideal opportunity to combat the pathogen via pharmacotherapeutic applications. However, a layer-by-layer nanocoating approach is also envisioned to coat surfaces to which humans are exposed that could harbor pathogenic coronaviruses. By coating masks, clothing, and work surfaces in wet markets among others, these antiviral polysaccharides can ensure passive prevention of the spreading of the virus. It poses a so-called "eradicate-in-place" measure against the virus. Antiviral polysaccharides also provide a green chemistry pathway to virus eradication since these molecules are primarily of biological origin and can be modified by minimal synthetic approaches. They are biocompatible as well as biodegradable. This surface passivation approach could provide a powerful measure against the spreading of coronaviruses.

The diagnosis of pandemic coronavirus pneumonia: A review of radiology examination and laboratory test

Since the outbreak of novel coronavirus disease 2019 (COVID-19), epidemic prevention strategies have been implemented worldwide. For the sake of controlling the infectious coronavirus pneumonia, early diagnosis and quarantine play an imperative role. Currently, the mainstream diagnostic methods are imaging and laboratory diagnosis, which differ in their efficacy of diagnosis. To compare the detection rate, we reviewed numerous literature on pneumonia caused by coronaviruses (SARS, MERS, and SARS-CoV-2) and analyzed two different ways of diagnosis. The results showed that the detection rate of computed tomography (CT) diagnosis was significantly higher than that of real-time quantitative polymerase chain reaction (qPCR) (P = 0.00697). Still, clinicians should combine radiology and laboratory methods to achieve a higher detection rate, so that instant isolation and treatment could be effectively conducted to curb the rampant spread of the epidemic.

Evidence and possible mechanisms of rare maternal-fetal transmission of SARS-CoV-2

While SARS-CoV-2 infection has spread rapidly worldwide, data remains scarce about the natural history of infection in pregnant women and the risk of mother-to-fetal transmission. Current data indicates that viral RNA levels in maternal blood are low and there is no evidence of placental infection with SARS-CoV-2. Published reports to date suggest that perinatal transmission of SARSCoV- 2 can occur but is rare. Among 179 newborns tested for SARS-CoV2 at birth from mothers with COVID-19, transmission was suspected in 8 cases, 5 with positive nasopharyngeal SARS-CoV-2 RT-PCR and 3 with SARS-CoV-2 IgM. However, these cases arise from maternal infection close to childbirth and there are no information about exposition during first or second trimester of pregnancy. Welldesigned prospective cohort studies with rigorous judgement criteria are needed to determine the incidence and risk factors for perinatal transmission of SARS-CoV-2.

Pathogenic viruses: Molecular detection and characterization

Pathogenic viruses are viruses that can infect and replicate within human cells and cause diseases. The continuous emergence and re-emergence of pathogenic viruses has become a major threat to public health. Whenever pathogenic viruses emerge, their rapid detection is critical to enable implementation of specific control measures and the limitation of virus spread. Further molecular characterization to better understand these viruses is required for the development of diagnostic tests and countermeasures. Advances in molecular biology techniques have revolutionized the procedures for detection and characterization of pathogenic viruses. The development of PCR-based techniques together with DNA sequencing technology, have provided highly sensitive and specific methods to determine virus circulation. Pathogenic viruses potentially having global catastrophic consequences may emerge in regions where capacity for their detection and characterization is limited. Development of a local capacity to rapidly identify new viruses is therefore critical. This article reviews the molecular biology of pathogenic viruses and the basic principles of molecular techniques commonly used for their detection and characterization. The principles of good laboratory practices for handling pathogenic viruses are also discussed. This review aims at providing researchers and laboratory personnel with an overview of the molecular biology of pathogenic viruses and the principles of molecular techniques and good laboratory practices commonly implemented for their detection and characterization.

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The continous emergence and re-emergence of pathogenic viruses has become a major threat to public health.

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PCR-based techniques together with DNA sequencing technology have provided highly sensitive and specific methods to determine virus circulation.

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Southeast Asia is considered to be vulnerable to potential outbreaks of pathogenic viruses. A number of pathogenic viruses have been reported to circulate in this region. The 2019 novel coronavirus has also been identified in Southeast Asia.

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Development of local capacity to rapidly identify new viruses is very important.

The scanning electron microscope in microbiology and diagnosis of infectious disease

Despite being an excellent tool for investigating ultrastructure, scanning electron microscopy (SEM) is less frequently used than transmission electron microscopy for microbes such as viruses or bacteria. Here we describe rapid methods that allow SEM imaging of fully hydrated, unfixed microbes without using conventional sample preparation methods. We demonstrate improved ultrastructural preservation, with greatly reduced dehydration and shrinkage, for specimens including bacteria and viruses such as Ebola virus using infiltration with ionic liquid on conducting filter substrates for SEM.

Viral glycoproteins: biological role and application in diagnosis

The viruses that infect humans cause a huge global disease burden and produce immense challenge towards healthcare system. Glycoproteins are one of the major components of human pathogenic viruses. They have been demonstrated to have important role(s) in infection and immunity. Concomitantly high titres of antibodies against these antigenic viral glycoproteins have paved the way for development of novel diagnostics. Availability of appropriate biomarkers is necessary for advance diagnosis of infectious diseases especially in case of outbreaks. As human mobilization has increased manifold nowadays, dissemination of infectious agents became quicker that paves the need of rapid diagnostic system. In case of viral infection it is an emergency as virus spreads and mutates very fast. This review encircles the vast arena of viral glycoproteins, their importance in health and disease and their diagnostic applications.

Differential expression of serum/plasma proteins in various infectious diseases: specific or nonspecific signatures

Apart from direct detection of the infecting organisms or biomarker of the pathogen itself, surrogate host markers are also useful for sensitive and early diagnosis of pathogenic infections. Early detection of pathogenic infections, discrimination among closely related diseases with overlapping clinical manifestations, and monitoring of disease progression can be achieved by analyzing blood biomarkers. Therefore, over the last decade large numbers of proteomics studies have been conducted to identify differentially expressed human serum/plasma proteins in different infectious diseases with the intent of discovering novel potential diagnostic/prognostic biomarkers. However, in-depth review of the literature indicates that many reported biomarkers are altered in the same way in multiple infectious diseases, regardless of the type of infection. This might be a consequence of generic acute phase reactions, while the uniquely modulated candidates in different pathogenic infections could be indicators of some specific responses. In this review article, we will provide a comprehensive analysis of differentially expressed serum/plasma proteins in various infectious diseases and categorize the protein markers associated with generic or specific responses. The challenges associated with the discovery, validation, and translational phases of serum/plasma biomarker establishment are also discussed.

Molecular Virology

This chapter describes common viral pathogens in humans with emphasis on the molecular diagnosis. Each section includes molecular characteristics, clinical presentation, and commonly used diagnostic methods (both conventional and molecular). Commercially available molecular diagnostic kits are preferentially described. Recommendations and guidelines (if available) for result interpretation and clinical approach are also included. For detailed methods, please refer to the chapter “Methodology and Instrumentation” in this book.

Molecular diagnosis of respiratory virus infections

The appearance of eight new respiratory viruses, including the SARS coronavirus in 2003 and swine-origin influenza A/H1N1 in 2009, in the human population in the past nine years has tested the ability of virology laboratories to develop diagnostic tests to identify these viruses. Nucleic acid based amplification tests (NATs) for respiratory viruses were first introduced two decades ago and today are utilized for the detection of both conventional and emerging viruses. These tests are more sensitive than other diagnostic approaches, including virus isolation in cell culture, shell vial culture (SVC), antigen detection by direct fluorescent antibody (DFA) staining, and rapid enzyme immunoassay (EIA), and now form the backbone of clinical virology laboratory testing around the world. NATs not only provide fast, accurate and sensitive detection of respiratory viruses in clinical specimens but also have increased our understanding of the epidemiology of both new emerging viruses such as the pandemic H1N1 influenza virus of 2009, and conventional viruses such as the common cold viruses, including rhinovirus and coronavirus. Multiplex polymerase chain reaction (PCR) assays introduced in the last five years detect up to 19 different viruses in a single test. Several multiplex PCR tests are now commercially available and tests are working their way into clinical laboratories. The final chapter in the evolution of respiratory virus diagnostics has been the addition of allelic discrimination and detection of single nucleotide polymorphisms associated with antiviral resistance. These assays are now being multiplexed with primary detection and subtyping assays, especially in the case of influenza virus. These resistance assays, together with viral load assays, will enable clinical laboratories to provide physicians with new and important information for optimal treatment of respiratory virus infections.

Nucleic acid amplification-based diagnosis of respiratory virus infections

The appearance of eight new respiratory viruses in the human population in the past 9 years, including two new pandemics (SARS coronavirus in 2003 and swine-origin influenza A/H1N1 in 2009), has tested the ability of virology laboratories to develop diagnostic tests to identify these viruses. Nucleic acid amplification tests (NATs) that first appeared two decades ago have been developed for both conventional and emerging viruses and now form the backbone of the clinical laboratory. NATs provide fast, accurate and sensitive detection of respiratory viruses and have significantly increased our understanding of the epidemiology of these viruses. Multiplex PCR assays have been introduced recently and several commercial tests are now available. The final chapter in the evolution of respiratory virus diagnostics will be the addition of allelic discrimination and detection of single nucleotide polymorphisms associated with antiviral resistance to multiplex assays. These resistance assays together with new viral load tests will enable clinical laboratories to provide physicians with important information for optimal treatment of patients.

Molecular Detection of Multiple Respiratory Viruses

This chapter discusses the molecular detection of multiple respiratory viruses. Respiratory infections are very common. They are responsible for significant morbidity and mortality and are costly in terms of lost time from work, inappropriate use of antibiotics, and lengthy hospital stays. Laboratory detection of causative agents can influence treatment and allow appropriate infection control measures, potentially saving time and money, promoting quicker recovery for the patient, and lowering the risk of nosocomial transmission of the organism. Molecular testing may be the most sensitive method of detecting respiratory viruses. These methods have been shown to detect multiple viruses in a single sample more often than any of the other methods described and, in addition, can detect viruses that are difficult or impossible to grow. The detection of nonviable organisms may provide additional insight into disease but provides its own challenges in terms of determining clinical significance of positive results. Like many areas of clinical medicine and microbiology, the increasing use of molecular diagnostics for detection of respiratory viruses raises many new questions for the laboratory and the clinical diagnostician, but also promises many benefits as these methods become increasingly available for routine use.

Development of an enzyme-linked immunosorbent assay-based test with a cocktail of nucleocapsid and spike proteins for detection of severe acute respiratory syndrome-associated coronavirus-specific antibody

A new enzyme-linked immunosorbent assay (ELISA)-based immunoglobulin G (IgG)-plus-IgM antibody detection test for severe acute respiratory syndrome (SARS) has been developed by using a cocktail of four recombinant polypeptides as the antigen. These recombinant fragments were designed as parts of two different structural proteins from SARS-associated coronavirus (SARS-CoV). One recombinant polypeptide, S251-683, was designed as part of the spike glycoprotein, and the other three polypeptides comprised almost the whole nucleocapsid protein, avoiding the last 25 C-terminal amino acids. Immunization with a cocktail of these four polypeptides yielded a specific polyclonal antibody that is able to recognize SARS-CoV-infected cells by an immunofluorescence assay. This polypeptide cocktail was also used to set up an ELISA-based IgG-plus-IgM antibody detection test, which showed 99% specificity and 90% sensitivity upon evaluation using sera from 100 healthy negative controls and 20 SARS patients. Separate immunoreactivity assays with each recombinant polypeptide demonstrated that a combination of N and S protein fragments was more suitable than the individual peptides for developing a serological assay for SARS-CoV.

Emerging pathogens: challenges and successes of molecular diagnostics

More than 50 emerging and reemerging pathogens have been identified during the last 40 years. Until 1992 when the Institute of Medicine issued a report that defined emerging infectious diseases, medicine had been complacent about such infectious diseases despite the alarm bells of infections with human immunodeficiency virus. Molecular tools have proven useful in discovering and characterizing emerging viruses and bacteria such as Sin Nombre virus (hantaviral pulmonary syndrome), hepatitis C virus, Bartonella henselae (cat scratch disease, bacillary angiomatosis), and Anaplasma phagocytophilum (human granulocytotropic anaplasmosis). The feasibility of applying molecular diagnostics to dangerous, fastidious, and uncultivated agents for which conventional tests do not yield timely diagnoses has achieved proof of concept for many agents, but widespread use of cost-effective, validated commercial assays has yet to occur. This review presents representative emerging viral respiratory infections, hemorrhagic fevers, and hepatitides, as well as bacterial and parasitic zoonotic, gastrointestinal, and pulmonary infections. Agent characteristics, epidemiology, clinical manifestations, and diagnostic methods are tabulated for another 22 emerging viruses and five emerging bacteria. The ongoing challenge to the field of molecular diagnostics is to apply contemporary knowledge to facilitate agent diagnosis as well as to further discoveries of novel pathogens.

Evolution of genomes, host shifts and the geographic spread of SARS-CoV and related coronaviruses

Severe acute respiratory syndrome (SARS) is a novel human illness caused by a previously unrecognized coronavirus (CoV) termed SARS-CoV. There are conflicting reports on the animal reservoir of SARS-CoV. Many of the groups that argue carnivores are the original reservoir of SARS-CoV use a phylogeny to support their argument. However, the phylogenies in these studies often lack outgroup and rooting criteria necessary to determine the origins of SARS-CoV. Recently, SARS-CoV has been isolated from various species of Chiroptera from China (e.g., Rhinolophus sinicus) thus leading to reconsideration of the original reservoir of SARS-CoV. We evaluated the hypothesis that SARS-CoV isolated from Chiroptera are the original zoonotic source for SARS-CoV by sampling SARS-CoV and non-SARS-CoV from diverse hosts including Chiroptera, as well as carnivores, artiodactyls, rodents, birds and humans. Regardless of alignment parameters, optimality criteria, or isolate sampling, the resulting phylogenies clearly show that the SARS-CoV was transmitted to small carnivores well after the epidemic of SARS in humans that began in late 2002. The SARS-CoV isolates from small carnivores in Shenzhen markets form a terminal clade that emerged recently from within the radiation of human SARS-CoV. There is evidence of subsequent exchange of SARS-CoV between humans and carnivores. In addition SARS-CoV was transmitted independently from humans to farmed pigs (Sus scrofa). The position of SARS-CoV isolates from Chiroptera are basal to the SARS-CoV clade isolated from humans and carnivores. Although sequence data indicate that Chiroptera are a good candidate for the original reservoir of SARS-CoV, the structural biology of the spike protein of SARS-CoV isolated from Chiroptera suggests that these viruses are not able to interact with the human variant of the receptor of SARS-CoV, angiotensin-converting enzyme 2 (ACE2). In SARS-CoV we study, both visually and statistically, labile genomic fragments and, putative key mutations of the spike protein that may be associated with host shifts. We display host shifts and candidate mutations on trees projected in virtual globes depicting the spread of SARS-CoV. These results suggest that more sampling of coronaviruses from diverse hosts, especially Chiroptera, carnivores and primates, will be required to understand the genomic and biochemical evolution of coronaviruses, including SARS-CoV. © The Willi Hennig Society 2008.

Molecular diagnostic methods in pneumonia

PURPOSE OF REVIEW

Molecular techniques offer the promise of improving diagnosis of lower respiratory tract infections. This review focuses on currently used molecular diagnostic techniques for various types of pneumonia and highlights potential future applications of this technology.

RECENT FINDINGS

Lower respiratory tract infections result in a high degree of morbidity and mortality, but a definitive microbiologic diagnosis is often not obtained by traditional culture or serologic methods. In addition, culture of certain organisms may be difficult or require extended periods of time. Molecular techniques have the potential to improve diagnostic yield and decrease time to pathogen identification. These techniques are also helpful in the determination of drug sensitivity and the understanding of transmission and outbreaks. Most currently used techniques employ some variation of the polymerase chain reaction. Limitations include high costs, the need for specialized equipment, and problems with false-positive and -negative results.

SUMMARY

Molecular diagnosis of pneumonia has the potential to improve identification of pathogens in patients with suspected lower respiratory tract infection. Limitations of molecular techniques currently prevent their widespread use, but future developments will likely lead to inclusion of these tests in routine diagnostic evaluations.

Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)

Severe acute respiratory syndrome (SARS) is caused by a coronavirus (CoV), SARSCoV. SARS-CoV belongs to the family Coronaviridae, which are enveloped RNA viruses in the order Nidovirales. Global research efforts are continuing to increase the understanding of the virus, the pathogenesis of the disease it causes (SARS), and the “heterogeneity of individual infectiousness” as well as shedding light on how to prepare for other emerging viral diseases. Promising drugs and vaccines have been identified. The milestones achieved have resulted from a truly international effort. Molecular studies dissected the adaptation of this virus as it jumped from an intermediary animal, the civet, to humans, thus providing valuable insights into processes of molecular emergence.