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1.
Viruses ; 14(5)2022 04 21.
Article in English | MEDLINE | ID: covidwho-1822442

ABSTRACT

A canine coronavirus (CCoV) has now been reported from two independent human samples from Malaysia (respiratory, collected in 2017-2018; CCoV-HuPn-2018) and Haiti (urine, collected in 2017); these two viruses were nearly genetically identical. In an effort to identify any novel adaptations associated with this apparent shift in tropism we carried out detailed evolutionary analyses of the spike gene of this virus in the context of related Alphacoronavirus 1 species. The spike 0-domain retains homology to CCoV2b (enteric infections) and Transmissible Gastroenteritis Virus (TGEV; enteric and respiratory). This domain is subject to relaxed selection pressure and an increased rate of molecular evolution. It contains unique amino acid substitutions, including within a region important for sialic acid binding and pathogenesis in TGEV. Overall, the spike gene is extensively recombinant, with a feline coronavirus type II strain serving a prominent role in the recombinant history of the virus. Molecular divergence time for a segment of the gene where temporal signal could be determined, was estimated at around 60 years ago. We hypothesize that the virus had an enteric origin, but that it may be losing that particular tropism, possibly because of mutations in the sialic acid binding region of the spike 0-domain.


Subject(s)
Coronavirus, Canine , Animals , Cats , Dogs , N-Acetylneuraminic Acid , Spike Glycoprotein, Coronavirus/genetics , Tropism , Zoonoses
2.
Comp Med ; 71(5): 442-450, 2021 10 01.
Article in English | MEDLINE | ID: covidwho-1464198

ABSTRACT

With a presumed origin in bats, the COVID-19 pandemic has been a major source of morbidity and mortality in the hu- man population, and the causative agent, SARS-CoV-2, aligns most closely at the genome level with the bat coronaviruses RaBtCoV4991/RaTG13 and RmYN02. The ability of bats to provide reservoirs of numerous viruses in addition to coronaviruses remains an active area of research. Unique aspects of the physiology of the chiropteran immune system may contribute to the ability of bats to serve as viral reservoirs. The coronavirus spike protein plays important roles in viral pathogenesis and the immune response. Although much attention has focused on the spike receptor-binding domain, a unique aspect of SARS-CoV-2 as compared with its closest relatives is the presence of a furin cleavage site in the S1-S2 region of the spike protein. Proteolytic activation is likely an important feature that allows SARS-CoV-2-and other coronaviruses-to overcome the species barriers and thus cause human disease. The diversity of bat species limits the ability to draw broad conclusions about viral pathogenesis, but comparisons across species and with reference to humans and other susceptible mammals may guide future research in this regard.


Subject(s)
COVID-19 , Chiroptera , Animals , Genome, Viral , Humans , Pandemics , Phylogeny , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/genetics
3.
Methods Mol Biol ; 2099: 21-37, 2020.
Article in English | MEDLINE | ID: covidwho-1292545

ABSTRACT

The coronavirus spike envelope glycoprotein is an essential viral component that mediates virus entry events. Biochemical assessment of the spike protein is critical for understanding structure-function relationships and the roles of the protein in the viral life cycle. Coronavirus spike proteins are typically proteolytically processed and activated by host cell enzymes such as trypsin-like proteases, cathepsins, or proprotein-convertases. Analysis of coronavirus spike proteins by western blot allows the visualization and assessment of proteolytic processing by endogenous or exogenous proteases. Here, we present a method based on western blot analysis to investigate spike protein proteolytic cleavage by transient transfection of HEK-293 T cells allowing expression of the spike protein of the highly pathogenic Middle East respiratory syndrome coronavirus in the presence or absence of a cellular trypsin-like transmembrane serine protease, matriptase. Such analysis enables the characterization of cleavage patterns produced by a host protease on a coronavirus spike glycoprotein.


Subject(s)
Coronavirus Infections/virology , Middle East Respiratory Syndrome Coronavirus/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Blotting, Western , Cell Line , Humans , Middle East Respiratory Syndrome Coronavirus/pathogenicity , Protein Processing, Post-Translational , Proteolysis , Serine Endopeptidases/metabolism , Virus Internalization
4.
One Health ; 13: 100282, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1275604

ABSTRACT

Bats and rodents comprise two of the world's largest orders of mammals and the order Chiroptera (bats) has been implicated as a major reservoir of coronaviruses in nature and a source of zoonotic transfer to humans. However, the order Rodentia (rodents) also harbors coronaviruses, with two human coronaviruses (HCoV-OC43 and HCoV-HKU1) considered to have rodent origins. The coronavirus spike protein mediates viral entry and is a major determinant of viral tropism; importantly, the spike protein is activated by host cell proteases at two distinct sites, designated as S1/S2 and S2'. SARS-CoV-2, which is considered to be of bat origin, contains a cleavage site for the protease furin at S1/S2, absent from the rest of the currently known betacoronavirus lineage 2b coronaviruses (Sarbecoviruses). This cleavage site is thought to be critical to its replication and pathogenesis, with a notable link to virus transmission. Here, we examine the spike protein across coronaviruses identified in both bat and rodent species and address the role of furin as an activating protease. Utilizing two publicly available furin prediction algorithms (ProP and PiTou) and based on spike sequences reported in GenBank, we show that the S1/S2 furin cleavage site is typically not present in bat virus spike proteins but is common in rodent-associated sequences, and suggest this may have implications for zoonotic transfer. We provide a phylogenetic history of the Embecoviruses (betacoronavirus lineage 2a), including context for the use of furin as an activating protease for the viral spike protein. From a One Health perspective, continued rodent surveillance should be an important consideration in uncovering novel circulating coronaviruses.

5.
Curr Opin Virol ; 47: 113-120, 2021 04.
Article in English | MEDLINE | ID: covidwho-1120446

ABSTRACT

Because of the COVID-19 pandemic, the novel coronavirus SARS-CoV-2 has risen to shape scientific research during 2020, with its spike (S) protein being a predominant focus. The S protein is likely the most complicated of all viral glycoproteins and is a key factor in immunological responses and virus pathogenesis. It is also the driving force dictating virus entry mechanisms, which are highly 'plastic' for coronaviruses, allowing a plethora of options for different virus variants and strains in different cell types. Here we review coronavirus entry as a foundation for current work on SARS-CoV-2. We focus on the post-receptor binding events and cellular pathways that direct the membrane fusion events necessary for genome delivery, including S proteolytic priming and activation. We also address aspects of the entry process important for virus evolution and therapeutic development.


Subject(s)
COVID-19/etiology , SARS-CoV-2/physiology , Virus Internalization , COVID-19/drug therapy , COVID-19/transmission , Humans , Signal Transduction/physiology , Spike Glycoprotein, Coronavirus/physiology , Virus Internalization/drug effects
6.
mBio ; 12(1)2021 01 19.
Article in English | MEDLINE | ID: covidwho-1066820

ABSTRACT

Among the animal superfamily Musteloidea, which includes those commonly known as mustelids, naturally occurring and species-specific alphacoronavirus infections have been observed in both mink (Mustela vison / Neovison vison) and domestic ferrets (Mustela putorius furo). Ferret systemic coronavirus (FRSCV), in particular, has been associated with a rare but fatal systemic disease. In recent months, it has become apparent that both minks and ferrets are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a betacoronavirus and the cause of the coronavirus disease 2019 (COVID-19) pandemic. Several mink farms have experienced SARS-CoV-2 outbreaks, and experimental models have demonstrated susceptibility of ferrets to SARS-CoV-2. The potential for pet ferrets to become infected with SARS-CoV-2, however, remains elusive. During the 2002-2003 SARS epidemic, it was also apparent that ferrets were susceptible to SARS-CoV and could be utilized in vaccine development. From a comparative standpoint, understanding the relationships between different infections and disease pathogenesis in the animal superfamily Musteloidea may help elucidate viral infection and transmission mechanisms, as well as treatment and prevention strategies for coronaviruses.


Subject(s)
Caniformia/virology , Coronavirus Infections/veterinary , Coronavirus/classification , Animals , COVID-19/veterinary , COVID-19/virology , Coronavirus/isolation & purification , Coronavirus Infections/transmission , Coronavirus Infections/virology , Disease Outbreaks/veterinary , Disease Susceptibility , Farms , Phylogeny , SARS-CoV-2/isolation & purification , Species Specificity
7.
FEMS Microbiol Rev ; 45(3)2021 05 05.
Article in English | MEDLINE | ID: covidwho-894587

ABSTRACT

Coronaviruses are a group of viruses causing disease in a wide range of animals, and humans. Since 2002, the successive emergence of bat-borne severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), swine acute diarrhea syndrome coronavirus (SADS-CoV) and SARS-CoV-2 has reinforced efforts in uncovering the molecular and evolutionary mechanisms governing coronavirus cell tropism and interspecies transmission. Decades of studies have led to the discovery of a broad set of carbohydrate and protein receptors for many animal and human coronaviruses. As the main determinant of coronavirus entry, the spike protein binds to these receptors and mediates membrane fusion. Prone to mutations and recombination, spike evolution has been studied extensively. The interactions between spike proteins and their receptors are often complex and despite many advances in the field, there remains many unresolved questions concerning coronavirus tropism modification and cross-species transmission, potentially leading to delays in outbreak responses. The emergence of SARS-CoV-2 underscores the need to address these outstanding issues in order to better anticipate new outbreaks. In this review, we discuss the latest advances in the field of coronavirus receptors emphasizing on the molecular and evolutionary processes that underlie coronavirus receptor usage and host range expansion.


Subject(s)
Coronavirus Infections/metabolism , Coronavirus Infections/virology , Coronavirus/classification , Coronavirus/physiology , Host-Pathogen Interactions , Receptors, Coronavirus/metabolism , Animals , Biodiversity , COVID-19/metabolism , COVID-19/virology , Genotype , Host Specificity , Humans , Phylogeny , Receptors, Coronavirus/chemistry , Receptors, Coronavirus/classification , SARS-CoV-2/classification , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Viral Tropism
8.
ArXiv; 2020.
Preprint | ArXiv | ID: ppcovidwho-480

ABSTRACT

The 2019 novel coronavirus (2019-nCoV) is currently causing a widespread outbreak centered on Hubeprovince, China and is a major public health concern. Taxonomically 2019-nCoV is closely related to SARS-CoV and SARS-related bat coronaviruses, and it appears to share a common receptor with SARS-CoV (ACE-2). Here, we perform structural modeling of the 2019-nCoV spike glycoprotein. Our data provide support for the similar receptor utilization between 2019-nCoV and SARS-CoV, despite a relatively low amino acid similarity in the receptor binding module. Compared to SARS-CoV, we identify an extended structural loocontaining basic amino acids at the interface of the receptor binding (S1) and fusion (S2) domains, which we predict to be proteolytically-sensitive. We suggest this looconfers fusion activation and entry properties more in line with MERS-CoV and other coronaviruses, and that the presence of this structural looin 2019-nCoV may affect virus stability and transmission.

9.
Viruses ; 12(1)2020 01 10.
Article in English | MEDLINE | ID: covidwho-783748

ABSTRACT

Feline coronavirus (FCoV) is a complex viral agent that causes a variety of clinical manifestations in cats, commonly known as feline infectious peritonitis (FIP). It is recognized that FCoV can occur in two different serotypes. However, differences in the S protein are much more than serological or antigenic variants, resulting in the effective presence of two distinct viruses. Here, we review the distinct differences in the S proteins of these viruses, which are likely to translate into distinct biological outcomes. We introduce a new concept related to the non-taxonomical classification and differentiation among FCoVs by analyzing and comparing the genetic, structural, and functional characteristics of FCoV and the FCoV S protein among the two serotypes and FCoV biotypes. Based on our analysis, we suggest that our understanding of FIP needs to consider whether the presence of these two distinct viruses has implications in clinical settings.


Subject(s)
Coronavirus, Feline/genetics , Feline Infectious Peritonitis/virology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Animals , Cats , Coronavirus, Feline/metabolism , Coronavirus, Feline/pathogenicity , Feline Infectious Peritonitis/metabolism , Membrane Fusion , Models, Molecular , Receptors, Virus/metabolism , Serogroup , Species Specificity , Spike Glycoprotein, Coronavirus/genetics
10.
Vet Microbiol ; 247: 108777, 2020 Aug.
Article in English | MEDLINE | ID: covidwho-733593

ABSTRACT

Coronaviruses (CoVs) cause disease in a range of agricultural and companion animal species, and can be important causes of zoonotic infections. In humans, several coronaviruses circulate seasonally. Recently, a novel zoonotic CoV named SARS-CoV-2 emerged from a bat reservoir, resulting in the COVID-19 pandemic. With a focus on felines, we review here the evidence for SARS-CoV-2 infection in cats, ferrets and dogs, describe the relationship between SARS-CoV-2 and the natural coronaviruses known to infect these species, and provide a rationale for the relative susceptibility of these species to SARS-CoV-2 through comparative analysis of the ACE-2 receptor.


Subject(s)
Cat Diseases/virology , Coronavirus Infections/veterinary , Dog Diseases/virology , Evolution, Molecular , Pandemics/veterinary , Pneumonia, Viral/veterinary , Zoonoses/transmission , Angiotensin-Converting Enzyme 2 , Animals , Betacoronavirus , COVID-19 , Cats/virology , Dogs/virology , Ferrets/virology , Humans , Peptidyl-Dipeptidase A/metabolism , Receptors, Coronavirus , Receptors, Virus/genetics , SARS-CoV-2 , Zoonoses/virology
11.
iScience ; 23(6): 101212, 2020 Jun 26.
Article in English | MEDLINE | ID: covidwho-401209

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 19 (COVID-19) has rapidly spread to the entire world within a few months. The origin of SARS-CoV-2 has been related to the lineage B Betacoronavirus SARS-CoV and SARS-related coronaviruses found in bats. Early characterizations of the SARS-CoV-2 genome revealed the existence of a distinct four amino acid insert within the spike (S) protein (underlined, SPRRAR↓S), at the S1/S2 site located at the interface between the S1 receptor binding subunit and the S2 fusion subunit. Notably, this insert appears to be a distinguishing feature among SARS-related sequences and introduces a potential cleavage site for the protease furin. Here, we investigate the potential role of this novel S1/S2 cleavage site and present direct biochemical evidence for proteolytic processing by a variety of proteases. We discuss these findings in the context of the origin of SARS-CoV-2, viral stability, and transmission.

12.
J Mol Biol ; 432(10): 3309-3325, 2020 05 01.
Article in English | MEDLINE | ID: covidwho-72124

ABSTRACT

The 2019 novel coronavirus (2019-nCoV/SARS-CoV-2) originally arose as part of a major outbreak of respiratory disease centered on Hubei province, China. It is now a global pandemic and is a major public health concern. Taxonomically, SARS-CoV-2 was shown to be a Betacoronavirus (lineage B) closely related to SARS-CoV and SARS-related bat coronaviruses, and it has been reported to share a common receptor with SARS-CoV (ACE-2). Subsequently, betacoronaviruses from pangolins were identified as close relatives to SARS-CoV-2. Here, we perform structural modeling of the SARS-CoV-2 spike glycoprotein. Our data provide support for the similar receptor utilization between SARS-CoV-2 and SARS-CoV, despite a relatively low amino acid similarity in the receptor binding module. Compared to SARS-CoV and all other coronaviruses in Betacoronavirus lineage B, we identify an extended structural loop containing basic amino acids at the interface of the receptor binding (S1) and fusion (S2) domains. We suggest this loop confers fusion activation and entry properties more in line with betacoronaviruses in lineages A and C, and be a key component in the evolution of SARS-CoV-2 with this structural loop affecting virus stability and transmission.


Subject(s)
Betacoronavirus/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Amino Acid Sequence , Animals , Betacoronavirus/genetics , COVID-19 , Chiroptera/virology , Coronavirus Infections/veterinary , Coronavirus Infections/virology , Eutheria , Humans , Models, Molecular , Pandemics , Phylogeny , Pneumonia, Viral/virology , Proteolysis , SARS Virus/chemistry , SARS-CoV-2 , Sequence Alignment
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