Canine Respiratory Coronavirus, Bovine Coronavirus, and Human Coronavirus OC43: Receptors and Attachment Factors

Seasonal human coronaviruses OC43, 229E, and NL63 induce cell surface modulation of entry receptors and display host cell-specific viral replication kinetics

The emergence of the COVID-19 pandemic prompted an increased interest in seasonal human coronaviruses. OC43, 229E, NL63, and HKU1 are endemic seasonal coronaviruses that cause the common cold and are associated with generally mild respiratory symptoms. In this study, we identified cell lines that exhibited cytopathic effects (CPE) upon infection by three of these coronaviruses and characterized their viral replication kinetics and the effect of infection on host surface receptor expression. We found that NL63 produced CPE in LLC-MK2 cells, while OC43 produced CPE in MRC-5, HCT-8, and WI-38 cell lines, while 229E produced CPE in MRC-5 and WI-38 by day 3 post-infection. We observed a sharp increase in nucleocapsid and spike viral RNA (vRNA) from day 3 to day 5 post-infection for all viruses; however, the abundance and the proportion of vRNA copies measured in the supernatants and cell lysates of infected cells varied considerably depending on the virus-host cell pair. Importantly, we observed modulation of coronavirus entry and attachment receptors upon infection. Infection with 229E and OC43 led to a downregulation of CD13 and GD3, respectively. In contrast, infection with NL63 and OC43 leads to an increase in ACE2 expression. Attempts to block entry of NL63 using either soluble ACE2 or anti-ACE2 monoclonal antibodies demonstrated the potential of these strategies to greatly reduce infection. Overall, our results enable a better understanding of seasonal coronaviruses infection kinetics in permissive cell lines and reveal entry receptor modulation that may have implications in facilitating co-infections with multiple coronaviruses in humans.IMPORTANCESeasonal human coronavirus is an important cause of the common cold associated with generally mild upper respiratory tract infections that can result in respiratory complications for some individuals. There are no vaccines available for these viruses, with only limited antiviral therapeutic options to treat the most severe cases. A better understanding of how these viruses interact with host cells is essential to identify new strategies to prevent infection-related complications. By analyzing viral replication kinetics in different permissive cell lines, we find that cell-dependent host factors influence how viral genes are expressed and virus particles released. We also analyzed entry receptor expression on infected cells and found that these can be up- or down-modulated depending on the infecting coronavirus. Our findings raise concerns over the possibility of infection enhancement upon co-infection by some coronaviruses, which may facilitate genetic recombination and the emergence of new variants and strains.

Prevalence and Evolutionary Characteristics of Bovine Coronavirus in China

Bovine coronavirus (BCoV), bovine rotavirus, bovine viral diarrhea virus, and bovine astrovirus are the most common intestinal pathogenic viruses causing diarrhea in cattle. We collected 1646 bovine fecal samples from January 2020 to August 2023. BCoV was the major pathogen detected, with a positive rate of 34.02% (560/1646). Of the 670 diarrheal samples and 976 asymptomatic samples, 209 and 351 were BCoV-positive, respectively. Studying the relevance of diarrhea associated with BCoV has shown that the onset of diarrheal symptoms post-infection is strongly correlated with the cattle's age and may also be related to the breed. We amplified and sequenced the hemagglutinin esterase (HE), spike protein, and whole genomes of the partially positive samples and obtained six complete HE sequences, seven complete spike sequences, and six whole genomes. Molecular characterization revealed that six strains were branched Chinese strains, Japanese strains, and partial American strains from the GⅡb subgroup. Strains HBSJZ2202 and JSYZ2209 had four amino acid insertions on HE. We also analyzed ORF1a and found disparities across various regions within GIIb, which were positioned on separate branches within the phylogenetic tree. This work provides data for further investigating the epidemiology of BCoV and for understanding and analyzing BCoV distribution and dynamics.

Evolution of the coronavirus spike protein in the full-length genome and defective viral genome under diverse selection pressures

How coronaviruses evolve by altering the structures of their full-length genome and defective viral genome (DVG) under dynamic selection pressures has not been studied. In this study, we aimed to experimentally identify the dynamic evolutionary patterns of the S protein sequence in the full-length genome and DVG under diverse selection pressures, including persistence, innate immunity and antiviral drugs. The evolutionary features of the S protein sequence in the full-length genome and in the DVG under diverse selection pressures are as follows: (i) the number of nucleotide (nt) mutations does not necessarily increase with the number of selection pressures; (ii) certain types of selection pressure(s) can lead to specific nt mutations; (iii) the mutated nt sequence can be reverted to the wild-type nt sequence under the certain type of selection pressure(s); (iv) the DVG can also undergo mutations and evolve independently of the full-length genome; and (v) DVG species are regulated during evolution under diverse selection pressures. The various evolutionary patterns of the S protein sequence in the full-length genome and DVG identified in this study may contribute to coronaviral fitness under diverse selection pressures.

N-linked glycoproteins and host proteases are involved in swine acute diarrhea syndrome coronavirus entry

IMPORTANCE

Gaining insight into the cell-entry mechanisms of swine acute diarrhea syndrome coronavirus (SADS-CoV) is critical for investigating potential cross-species infections. Here, we demonstrated that pretreatment of host cells with tunicamycin decreased SADS-CoV attachment efficiency, indicating that N-linked glycosylation of host cells was involved in SADS-CoV entry. Common N-linked sugars Neu5Gc and Neu5Ac did not interact with the SADS-CoV S1 protein, suggesting that these molecules were not involved in SADS-CoV entry. Additionally, various host proteases participated in SADS-CoV entry into diverse cells with different efficiencies. Our findings suggested that SADS-CoV may exploit multiple pathways to enter cells, providing insights into intervention strategies targeting the cell entry of this virus.

Canine respiratory coronavirus in Thailand undergoes mutation and evidences a potential putative parent for genetic recombination

Canine respiratory coronavirus (CRCoV) is associated with canine infectious respiratory disease complex. Although its detection has been reported worldwide, the genomic characteristics and evolutionary patterns of this virus remain poorly defined. In this study, 21 CRCoV sequences obtained from dogs in Thailand during two episodes (2013-2015, group A; 2021-2022, group B) were characterized and analyzed. The genomic characteristics of Thai CRCoVs changed from 2013 to 2022 and showed a distinct phylogenetic cluster. Phylogenetic analysis of the spike (S) genes divided the analyzed CRCoV strains into five clades. The full-length genome characterization revealed that all Thai CRCoVs possessed a nonsense mutation within the nonstructural gene located between the S and envelope genes, leading to a truncated putative nonstructural protein. Group B Thai CRCoV strains represented the signature nonsynonymous mutations in the S gene that was not identified in group A Thai CRCoVs, suggesting the ongoing evolutionary process of Thai CRCoVs. Although no evidence of recombination of Thai CRCoV strains was found, our analysis identified one Thai CRCoV strain as a potential parent virus for a CRCoV strain found in the United States. Selective pressure analysis of the hypervariable S region indicated that the CRCoV had undergone purifying selection during evolution. Evolutionary analysis suggested that the CRCoV was emerged in 1992 and was first introduced in Thailand in 2004, sharing a common ancestor with Korean CRCoV strains. These findings regarding the genetic characterization and evolutionary analysis of CRCoVs add to the understanding of CRCoVs. IMPORTANCE Knowledge of genomic characterization of the CRCoV is still limited and its evolution remains poorly investigated. We, therefore, investigated the full-length genome of CRCoV in Thailand for the first time and analyzed the evolutionary dynamic of CRCoV. Genomic characterization of Thai CRCoV strains revealed that they possess unique genome structures and have undergone nonsynonymous mutations, which have not been reported in previously described CRCoV strains. Our work suggests that the Thai CRCoVs were not undergone mutation through genetic recombination for their evolution. However, one Thai CRCoV strain PP158_THA_2015 was found to be a potential parent virus for the CRCoV strains found in the United States. This study provides an understanding of the genomic characterization and highlights the signature mutations and ongoing evolutionary process of CRCoV that could be crucial for monitoring in the future.

Coronaviruses: Troubling Crown of the Animal Kingdom

The existence of coronaviruses has been known for many years. These viruses cause significant disease that primarily seems to affect agricultural species. Human coronavirus disease due to the 2002 outbreak of Severe Acute Respiratory Syndrome and the 2012 outbreak of Middle East Respiratory Syndrome made headlines; however, these outbreaks were controlled, and public concern quickly faded. This complacency ended in late 2019 when alarms were raised about a mysterious virus responsible for numerous illnesses and deaths in China. As we now know, this novel disease called Coronavirus Disease 2019 (COVID-19) was caused by Severe acute respiratory syndrome-related-coronavirus-2 (SARS-CoV-2) and rapidly became a worldwide pandemic. Luckily, decades of research into animal coronaviruses hastened our understanding of the genetics, structure, transmission, and pathogenesis of these viruses. Coronaviruses infect a wide range of wild and domestic animals, with significant economic impact in several agricultural species. Their large genome, low dependency on host cellular proteins, and frequent recombination allow coronaviruses to successfully cross species barriers and adapt to different hosts including humans. The study of the animal diseases provides an understanding of the virus biology and pathogenesis and has assisted in the rapid development of the SARS-CoV-2 vaccines. Here, we briefly review the classification, origin, etiology, transmission mechanisms, pathogenesis, clinical signs, diagnosis, treatment, and prevention strategies, including available vaccines, for coronaviruses that affect domestic, farm, laboratory, and wild animal species. We also briefly describe the coronaviruses that affect humans. Expanding our knowledge of this complex group of viruses will better prepare us to design strategies to prevent and/or minimize the impact of future coronavirus outbreaks.

Porcine deltacoronavirus uses heparan sulfate as an attachment receptor

Porcine deltacoronavirus (PDCoV) is a newly emerging swine enteropathogenic coronavirus with extensive tissue tropism and cross-species transmission potential. Heparan sulfate (HS) is a complex polysaccharide ubiquitously expressed on cell surfaces and the extracellular matrix and acts as an attachment factor for many viruses. However, whether PDCoV uses HS as an attachment receptor is unclear. In this study, we found that treatment with heparin sodium or heparinase Ⅱ significantly inhibited PDCoV binding and infection among LLC-PK1 and IPI-2I cells. Attenuation of HS sulfuration by sodium chlorate also impeded PDCoV binding and infection. Moreover, we demonstrated that HS functioned independently of amino peptidase N (APN), a functional PDCoV receptor, in PDCoV infection. Molecular docking revealed that the S1 subunit of the PDCoV spike protein might be a putative region for HS binding. Taken together, these results firstly confirmed that HS is an attachment receptor for PDCoV infection, providing new insight into better understanding the mechanisms of PDCoV-host interactions.

Review of the impact of COVID-19 on male reproduction, and its implications on assisted reproductive technology services

The announcement in 2019 of a new coronavirus disease that quickly became a major pandemic, is an exceptional challenge to healthcare systems never seen before. Such a public health emergency can largely influence various aspects of people’s health as well as reproductive outcome. IVF specialists should be vigilant, monitoring the situation whilst contributing by sharing novel evidence to counsel patients, both pregnant women and would-be mothers. Coronavirus infection might adversely affect pregnant women and their offspring. Consequently, this review paper aims to analyse its potential risks for reproductive health, as well as potential effects of the virus on gamete function and embryo development. In addition, reopening fertility clinics poses several concerns that need immediate addressing, such as the effect of severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) on reproductive cells and also the potential risk of cross-contamination and viral transmission. Therefore, this manuscript summarizes what is currently known about the effect of the SARS-CoV-2 infection on medically assisted reproductive treatments and its effect on reproductive health and pregnancy.

Microneedle Delivery of an Adjuvanted Microparticulate Vaccine Induces High Antibody Levels in Mice Vaccinated against Coronavirus

This ‘proof-of-concept’ study aimed to test the microparticulate vaccine delivery system and a transdermal vaccine administration strategy using dissolving microneedles (MN). For this purpose, we formulated poly(lactic-co-glycolic) acid (PLGA) microparticles (MP) encapsulating the inactivated canine coronavirus (iCCoV), as a model antigen, along with adjuvant MP encapsulating Alhydrogel^® and AddaVax. We characterized the vaccine MP for size, surface charge, morphology, and encapsulation efficiency. Further, we evaluated the in vitro immunogenicity, cytotoxicity, and antigen-presentation of vaccine/adjuvant MP in murine dendritic cells (DCs). Additionally, we tested the in vivo immunogenicity of the MP vaccine in mice through MN administration. We evaluated the serum IgG, IgA, IgG1, and IgG2a responses using an enzyme-linked immunosorbent assay. The results indicate that the particulate form of the vaccine is more immunogenic than the antigen suspension in vitro. We found the vaccine/adjuvant MP to be non-cytotoxic to DCs. The expression of antigen-presenting molecules, MHC I/II, and their costimulatory molecules, CD80/40, increased with the addition of the adjuvants. Moreover, the results suggest that the MP vaccine is cross presented by the DCs. In vivo, the adjuvanted MP vaccine induced increased antibody levels in mice following vaccination and will further be assessed for its cell-mediated responses.

PDSTP Is the First Drug in Class to Treat Coronavirus Infection

The results of a comprehensive study are presented on the development and creation of an original small PDSTP molecule, able to prevent the SARS-CoV-2 coronavirus infection from binding to the host cell. The PDSTP molecule was designed to electrostatically interact with heparan sulfate proteoglycans on the cell surface, and coronaviruses, particularly SARS-CoV-2, use this mechanism as the first stage of interaction with the cell. By blocking this process, it is possible to stop the life cycle of the virus, thus leading to its death. The drug candidate PDSTP, with its unique mechanism of action, is characterized by a very low toxicity and a high safety profile and demonstrates good efficacy in animal experiments.

The green tea catechin EGCG provides proof-of-concept for a pan-coronavirus attachment inhibitor

The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has emphasized the serious threat to human health posed by emerging coronaviruses. Effective broadly-acting antiviral countermeasures are urgently needed to prepare for future emerging CoVs, as vaccine development is not compatible with a rapid response to a newly emerging virus. The green tea catechin, epigallocatechin gallate (EGCG), has broad-spectrum antiviral activity, although its mechanisms against coronavirus (CoV) infection have remained unclear. Here, we show that EGCG prevents human and murine CoV infection and blocks the entry of lentiviral particles pseudotyped with spike proteins from bat or highly pathogenic CoVs, including SARS-CoV-2 variants of concern, in lung epithelial cells. Mechanistically, EGCG treatment reduces CoV attachment to target cell surfaces by interfering with attachment to cell-surface glycans. Heparan sulfate proteoglycans are a required attachment factor for SARS-CoV-2 and are shown here to be important in endemic HCoV-OC43 infection. We show that EGCG can compete with heparin, a heparan sulfate analog, for virion binding. Our results highlight heparan sulfate as a conserved cell attachment factor for CoVs, and demonstrate the potential for the development of pan-coronavirus attachment inhibitors, which may be useful to protect against future emerging CoVs.

Routine Decontamination of Surfaces Relevant to Working Dogs: Neutralization of Superficial Coronavirus Contamination

Given the increased deployment of working dogs to settings with pathogenic biological agents, a safe, effective, and logistically feasible surface decontamination protocol is essential to protect both the animals and their human handlers. Our group previously found that superficial contamination on surfaces relevant to the working dog community, including leashes and toys, could be significantly reduced using a standardized wiping protocol with various cleansing products. To expand upon this work, we analyzed the ability of this protocol to decontaminate surface-deposited bovine coronavirus, which was used as a BSL2 surrogate for SARS-CoV-2. Unsurprisingly, the physical characteristics of a given surface, including porosity and texture, had a significant effect on the ability to recover viable virus remaining on the surface post treatment. After correcting for these differences, however, wiping with 70% isopropyl alcohol (IPA) and 0.5% chlorhexidine performed best, reducing viral titers by >3 log on plastic bumper toys and nylon collars, and by >2 log on rubber toys and tennis balls. Leather leashes and Velcro proved more difficult to decontaminate, but both still showed significant loss of viral contamination following wiping with IPA or chlorhexidine. This work (i) validates the utility of a simple protocol for the neutralization of viruses on several surfaces, (ii) identifies materials that are more difficult to decontaminate, which should, thus, be considered for removal from field use, and (iii) highlights the need for further development of protocols testing porous or textured surfaces.

Potent universal beta-coronavirus therapeutic activity mediated by direct respiratory administration of a Spike S2 domain-specific human neutralizing monoclonal antibody

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) marks the third novel β-coronavirus to cause significant human mortality in the last two decades. Although vaccines are available, too few have been administered worldwide to keep the virus in check and to prevent mutations leading to immune escape. To determine if antibodies could be identified with universal coronavirus activity, plasma from convalescent subjects was screened for IgG against a stabilized pre-fusion SARS-CoV-2 spike S2 domain, which is highly conserved between human β-coronavirus. From these subjects, several S2-specific human monoclonal antibodies (hmAbs) were developed that neutralized SARS-CoV-2 with recognition of all variants of concern (VoC) tested (Beta, Gamma, Delta, Epsilon, and Omicron). The hmAb 1249A8 emerged as the most potent and broad hmAb, able to recognize all human β-coronavirus and neutralize SARS-CoV and MERS-CoV. 1249A8 demonstrated significant prophylactic activity in K18 hACE2 mice infected with SARS-CoV-2 lineage A and lineage B Beta, and Omicron VoC. 1249A8 delivered as a single 4 mg/kg intranasal (i.n.) dose to hamsters 12 hours following infection with SARS-CoV-2 Delta protected them from weight loss, with therapeutic activity further enhanced when combined with 1213H7, an S1-specific neutralizing hmAb. As little as 2 mg/kg of 1249A8 i.n. dose 12 hours following infection with SARS-CoV Urbani strain, protected hamsters from weight loss and significantly reduced upper and lower respiratory viral burden. These results indicate in vivo cooperativity between S1 and S2 specific neutralizing hmAbs and that potent universal coronavirus neutralizing mAbs with therapeutic potential can be induced in humans and can guide universal coronavirus vaccine development.

Advances in Bovine Coronavirus Epidemiology

Bovine coronavirus (BCoV) is a causative agent of enteric and respiratory disease in cattle. BCoV has also been reported to cause a variety of animal diseases and is closely related to human coronaviruses, which has attracted extensive attention from both cattle farmers and researchers. However, there are few comprehensive epidemiological reviews, and key information regarding the effect of S-gene differences on tissue tendency and potential cross-species transmission remain unclear. In this review, we summarize BCoV epidemiology, including the transmission, infection-associated factors, co-infection, pathogenicity, genetic evolution, and potential cross-species transmission. Furthermore, the potential two-receptor binding motif system for BCoV entry and the association between BCoV and SARS-CoV-2 are also discussed in this review. Our aim is to provide valuable information for the prevention and treatment of BCoV infection throughout the world.

A glucose-like metabolite deficient in diabetes inhibits cellular entry of SARS-CoV-2

The severity and mortality of COVID-19 are associated with pre-existing medical comorbidities such as diabetes mellitus. However, the underlying causes for increased susceptibility to viral infection in patients with diabetes is not fully understood. Here we identify several small-molecule metabolites from human blood with effective antiviral activity against SARS-CoV-2, one of which, 1,5-anhydro-D-glucitol (1,5-AG), is associated with diabetes mellitus. The serum 1,5-AG level is significantly lower in patients with diabetes. In vitro, the level of SARS-CoV-2 replication is higher in the presence of serum from patients with diabetes than from healthy individuals and this is counteracted by supplementation of 1,5-AG to the serum from patients. Diabetic (db/db) mice undergo SARS-CoV-2 infection accompanied by much higher viral loads and more severe respiratory tissue damage when compared to wild-type mice. Sustained supplementation of 1,5-AG in diabetic mice reduces SARS-CoV-2 loads and disease severity to similar levels in nondiabetic mice. Mechanistically, 1,5-AG directly binds the S2 subunit of the SARS-CoV-2 spike protein, thereby interrupting spike-mediated virus-host membrane fusion. Our results reveal a mechanism that contributes to COVID-19 pathogenesis in the diabetic population and suggest that 1,5-AG supplementation may be beneficial to diabetic patients against severe COVID-19.

Bovine coronavirus in the lower respiratory tract of cattle with respiratory disease

Bovine coronavirus (BCoV) is a known cause of enteric disease in cattle; however, its role in bovine respiratory disease (BRD) is poorly understood, with a dearth of evidence of the detection of the virus in respiratory tract lesions. We coupled histologic evaluation of tracheal and lower airway tissues from 104 calves with BRD in which BCoV was detected in the lungs via PCR followed by direct detection of BCoV by immunohistochemistry and an RNA in situ hybridization assay (ISH; RNAscope technology). RNAscope ISH detected BCoV in respiratory epithelium in more cases than did IHC. Using both methods of direct detection, tracheal epithelial attenuation and identification of the virus within lesions were observed commonly. Our results confirm a role of BCoV in respiratory tract infection and pathology, and show that the virus likely plays a role in the development of BRD.

Mucins Inhibit Coronavirus Infection in a Glycan-Dependent Manner

Mucins are a diverse and heterogeneous family of glycoproteins that comprise the bulk of mucus and the epithelial glycocalyx. Mucins are intimately involved in viral transmission. Mucin and virus laden particles can be expelled from the mouth and nose to later infect others. Viruses must also penetrate the mucus layer before cell entry and replication. The role of mucins and their molecular structure have not been well-characterized in coronavirus transmission studies. Laboratory studies predicting high rates of fomite transmission have not translated to real-world infections, and mucins may be one culprit. Here, we probed both surface and direct contact transmission scenarios for their dependence on mucins and their structure. We utilized disease-causing, bovine-derived, human coronavirus OC43. We found that bovine mucins could inhibit the infection of live cells in a concentration- and glycan-dependent manner. The effects were observed in both mock fomite and direct contact transmission experiments and were not dependent upon surface material or time-on-surface. However, the effects were abrogated by removal of the glycans or in a cross-species infection scenario where bovine mucin could not inhibit the infection of a murine coronavirus. Together, our data indicate that the mucin molecular structure plays a complex and important role in host defense.

Potent universal-coronavirus therapeutic activity mediated by direct respiratory administration of a Spike S2 domain-specific human neutralizing monoclonal antibody

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) marks the third novel β-coronavirus to cause significant human mortality in the last two decades. Although vaccines are available, too few have been administered worldwide to keep the virus in check and to prevent mutations leading to immune escape. To determine if antibodies could be identified with universal coronavirus activity, plasma from convalescent subjects was screened for IgG against a stabilized pre-fusion SARS-CoV-2 spike S2 domain, which is highly conserved between human β-coronavirus. From these subjects, several S2-specific human monoclonal antibodies (hmAbs) were developed that neutralized SARS-CoV-2 with recognition of all variants of concern (VoC) tested (Beta, Gamma, Delta, Epsilon, and Omicron). The hmAb 1249A8 emerged as the most potent and broad hmAb, able to recognize all human β-coronavirus and neutralize SARS-CoV and MERS-CoV. 1249A8 demonstrated significant prophylactic activity in K18 hACE2 mice infected with SARS-CoV-2 lineage A and lineage B Beta, and Omicron VoC. 1249A8 delivered as a single 4 mg/kg intranasal (i.n.) dose to hamsters 12 hours following infection with SARS-CoV-2 Delta protected them from weight loss, with therapeutic activity further enhanced when combined with 1213H7, an S1-specific neutralizing hmAb. As little as 2 mg/kg of 1249A8 i.n. dose 12 hours following infection with SARS-CoV Urbani strain, protected hamsters from weight loss and significantly reduced upper and lower respiratory viral burden. These results indicate in vivo cooperativity between S1 and S2 specific neutralizing hmAbs and that potent universal coronavirus neutralizing mAbs with therapeutic potential can be induced in humans and can guide universal coronavirus vaccine development.

High-Sulfated Glycosaminoglycans Prevent Coronavirus Replication

Coronaviruses (CoVs) are common among humans and many animals, causing respiratory or gastrointestinal diseases. Currently, only a few antiviral drugs against CoVs are available. Especially for SARS-CoV-2, new compounds for treatment of COVID-19 are urgently needed. In this study, we characterize the antiviral effects of two high-sulfated glycosaminoglycan (GAG) derivatives against SARS-CoV-2 and bovine coronaviruses (BCoV), which are both members of the Betacoronavirus genus. The investigated compounds are based on hyaluronan (HA) and chondroitin sulfate (CS) and exhibit a strong inhibitory effect against both CoVs. Yield assays were performed using BCoV-infected PT cells in the presence and absence of the compounds. While the high-sulfated HA (sHA3) led to an inhibition of viral growth early after infection, high-sulfated CS (sCS3) had a slightly smaller effect. Time of addition assays, where sHA3 and sCS3 were added to PT cells before, during or after infection, demonstrated an inhibitory effect during all phases of infection, whereas sHA3 showed a stronger effect even after virus absorbance. Furthermore, attachment analyses with prechilled PT cells revealed that virus attachment is not blocked. In addition, sHA3 and sCS3 inactivated BCoV by stable binding. Analysis by quantitative real-time RT PCR underlines the high potency of the inhibitors against BCoV, as well as B.1-lineage, Alpha and Beta SARS-CoV-2 viruses. Taken together, these results demonstrated that the two high-sulfated GAG derivatives exhibit low cytotoxicity and represent promising candidates for an anti-CoV therapy.

Known Cellular and Receptor Interactions of Animal and Human Coronaviruses: A Review

This article aims to review all currently known interactions between animal and human coronaviruses and their cellular receptors. Over the past 20 years, three novel coronaviruses have emerged that have caused severe disease in humans, including SARS-CoV-2 (severe acute respiratory syndrome virus 2); therefore, a deeper understanding of coronavirus host-cell interactions is essential. Receptor-binding is the first stage in coronavirus entry prior to replication and can be altered by minor changes within the spike protein-the coronavirus surface glycoprotein responsible for the recognition of cell-surface receptors. The recognition of receptors by coronaviruses is also a major determinant in infection, tropism, and pathogenesis and acts as a key target for host-immune surveillance and other potential intervention strategies. We aim to highlight the need for a continued in-depth understanding of this subject area following on from the SARS-CoV-2 pandemic, with the possibility for more zoonotic transmission events. We also acknowledge the need for more targeted research towards glycan-coronavirus interactions as zoonotic spillover events from animals to humans, following an alteration in glycan-binding capability, have been well-documented for other viruses such as Influenza A.

SARS-CoV-2 Mutations and their Viral Variants

Mutations in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occur spontaneously during replication. Thousands of mutations have accumulated and continue to since the emergence of the virus. As novel mutations continue appearing at the scene, naturally, new variants are increasingly observed. Since the first occurrence of the SARS-CoV-2 infection, a wide variety of drug compounds affecting the binding sites of the virus have begun to be studied. As the drug and vaccine trials are continuing, it is of utmost importance to take into consideration the SARS-CoV-2 mutations and their respective frequencies since these data could lead the way to multi-drug combinations. The lack of effective therapeutic and preventive strategies against human coronaviruses (hCoVs) necessitates research that is of interest to the clinical applications. The reason why the mutations in glycoprotein S lead to vaccine escape is related to the location of the mutation and the affinity of the protein. At the same time, it can be said that variations should occur in areas such as the receptor-binding domain (RBD), and vaccines and antiviral drugs should be formulated by targeting more than one viral protein. In this review, a literature survey in the scope of the increasing SARS-CoV-2 mutations and the viral variations is conducted. In the light of current knowledge, the various disguises of the mutant SARS-CoV-2 forms and their apparent differences from the original strain are examined as they could possibly aid in finding the most appropriate therapeutic approaches.

Hyperglycemia and Angiotensin-Converting Enzyme 2 in Pulmonary Function in the Context of SARS-CoV-2 Infection

Since the appearance of the severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003 in China, diabetes mellitus (DM) and hyperglycemia in patients infected with SARS-CoV, represent independent predictors of mortality. Therefore, metabolic control has played a major role in the prognosis of these patients. In the current pandemic of coronavirus disease 19 (COVID-19), multiple studies have shown that DM is one of the main comorbidities associated with COVID-19 and higher risk of complications and death. The incidence and prevalence of COVID-19 complications and death related with hyperglycemia in patients with or without DM are high. There are many hypotheses related with worse prognosis and death related to COVID-19 and/or hyperglycemia. However, the information about the interplay between hyperglycemia and angiotensin-converting enzyme 2 (ACE2), the critical receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in the context of SARS-CoV-2 infection, is almost null, but there is enough information to consider the possible participation of hyperglycemia in the glycation of this protein, unleashing a pool of reactions leading to acute respiratory distress syndrome and death in patients with COVID-19. In this document we investigated the current evidence related with ACE2 as a key element within the pathophysiological mechanism related with hyperglycemia extrapolating it to context of SARS-CoV-2 infection and its relationship with worse prognosis and death for COVID-19.

One Health: EAACI Position Paper on coronaviruses at the human-animal interface, with a specific focus on comparative and zoonotic aspects of SARS-CoV-2

The latest outbreak of a coronavirus disease in 2019 (COVID‐19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), evolved into a worldwide pandemic with massive effects on health, quality of life, and economy. Given the short period of time since the outbreak, there are several knowledge gaps on the comparative and zoonotic aspects of this new virus. Within the One Health concept, the current EAACI position paper dwells into the current knowledge on SARS‐CoV‐2’s receptors, symptoms, transmission routes for human and animals living in close vicinity to each other, usefulness of animal models to study this disease and management options to avoid intra‐ and interspecies transmission. Similar pandemics might appear unexpectedly and more frequently in the near future due to climate change, consumption of exotic foods and drinks, globe‐trotter travel possibilities, the growing world population, the decreasing production space, declining room for wildlife and free‐ranging animals, and the changed lifestyle including living very close to animals. Therefore, both the society and the health authorities need to be aware and well prepared for similar future situations, and research needs to focus on prevention and fast development of treatment options (medications, vaccines).

Two novel human coronavirus OC43 genotypes circulating in hospitalized children with pneumonia in China

HCoV-OC43 is one of the mildly pathogenic coronaviruses with high infection rates in common population. Here, 43 HCoV-OC43 related cases with pneumonia were reported, corresponding genomes of HCoV-OC43 were obtained. Phylogenetic analyses based on complete genome, orf1ab and spike genes revealed that two novel genotypes of HCoV-OC43 have emerged in China. Obvious recombinant events also can be detected in the analysis of the evolutionary dynamics of novel HCoV-OC43 genotypes. Estimated divergence time analysis indicated that the two novel genotypes had apparently independent evolutionary routes. Efforts should be conducted for further investigation of genomic diversity and evolution analysis of mildly pathogenic coronaviruses.

Zoonotic spillover of SARS-CoV-2: mink-adapted virus in humans

Objectives

This work aimed to analyse possible zoonotic spill-over of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We report the spill-over of mink-adapted SARS-CoV-2 from farmed mink to humans after adaptation that lasted at least 3 months.

Methods

Next-generation sequencing and a bioinformatic approach were applied to analyse the data.

Results

In an isolate obtained from an asymptomatic patient testing positive for SARS-CoV-2, we found four distinguishing mutations in the S gene that gave rise to the mink-adapted variant (G75V, M177T, Y453F, and C1247F) and others.

Conclusions

Zoonotic spill-over of SARS-CoV-2 can occur from mink to human.

Interactions between Cryptosporidium parvum and bovine corona virus during sequential and simultaneous infection of HCT-8 cells

Neonatal diarrhoea in calves is one of the major health problems in the cattle industry. Although co-infections are often associated with greater severity of disease, there is limited information on any impact on the pathogens themselves. Herein, we studied Cryptosporidium parvum and bovine coronavirus (BCoV) in human HCT-8 cells, inoculated either sequentially or simultaneously, to investigate any influence from the co-infections. Quantitative results from (RT)-qPCR showed that prior inoculation with either of the two pathogens had no influence on the other. However, the results from simultaneous co-inoculation showed that entry of viral particles was higher when C. parvum sporozoites were present, although elevated virus copy numbers were no longer evident after 24 h. The attachment of BCoV to the sporozoites was probably due to specific binding, as investigations with bovine norovirus or equine herpes virus-1 showed no attachment between sporozoites and these viruses. Flow cytometry results at 72 h post inoculation revealed that C. parvum and BCoV infected 1-11% and 10-20% of the HCT-8 cells, respectively, with only 0.04% of individual cells showing double infections. The results from confocal microscopy corroborated those results, showing an increase in foci of infection from 24-72 h post inoculation for both pathogens, but with few double infected cells.

Epidemiological survey and genetic diversity of bovine coronavirus in Northeast China

In 2020, to trace the prevalence and evolution of bovine coronavirus (BCoV) in China, a total of 1383 samples (1016 fecal samples and 367 nasal swab samples) were collected from 1016 cattle exhibiting diarrhea symptoms on dairy farms and beef cattle farms in Heilongjiang Province, Northeast China. All samples were subjected to reverse transcription-polymerase chain reaction (RT-PCR) detection of the BCoV N gene, followed by an analysis of its epidemiology and genetic evolution. The results indicated that of the 1016 diarrhea-affected cattle, 15.45% (157/1016) were positive for BCoV, in which positive rates of the fecal and nasal swab samples were 12.20% (124/1016) and 21.53% (79/367), respectively. Of the 367 cattle whose nasal swab samples were collected, the BCoV positive rate of the corresponding fecal samples was 15.26% (56/367). BCoV infection was significantly associated with age, farming pattern, cattle type, farm latitude, sample type, and clinical symptom (p < 0.05). Of the 203 BCoV-positive samples, 20 spike (S) genes were successfully sequenced. The 20 identified BCoV strains shared nucleotide homologies of 97.7-100.0%, and their N-terminal domain of S1 subunit (S1-NTD: residues 15-298) differed genetically from the reference strains of South Korea and Europe. The 20 identified BCoV strains were clustered in the Asia-North America group (GII group) in the global strain-based phylogenetic tree and formed three clades in the Chinese strain-based phylogenetic tree. The HLJ/HH-10/2020 strain was clustered into the Europe group (GI group) in the S1-NTD-based phylogenetic tree, exhibiting N¹⁴⁶/I, D¹⁴⁸/G, and L¹⁵⁴/F mutations that affect the S protein structure. Of the identified BCoV strains, one potential recombination event occurred between the HLJ/HH-20/2020 and HLJ/HH-10/2020 strains, which led to the generation of the recombinant BCV-AKS-01 strain. A selective pressure analysis on the S protein revealed one positively selected site (Asn⁵⁰⁹) among the 20 identified BCoV strains located inside the putative receptor binding domain (residues 326-540). These data provide a greater understanding of the epidemiology and evolution of BCoV in China.

Cell entry by SARS-CoV-2

Severe acute respiratory syndrome virus 2 (SARS-CoV-2) invades host cells by interacting with receptors/coreceptors, as well as with other cofactors, via its spike (S) protein that further mediates fusion between viral and cellular membranes. The host membrane protein, angiotensin-converting enzyme 2 (ACE2), is the major receptor for SARS-CoV-2 and is a crucial determinant for cross-species transmission. In addition, some auxiliary receptors and cofactors are also involved that expand the host/tissue tropism of SARS-CoV-2. After receptor engagement, specific proteases are required that cleave the S protein and trigger its fusogenic activity. Here we discuss the recent advances in understanding the molecular events during SARS-CoV-2 entry which will contribute to developing vaccines and therapeutics.

Cell Entry of Animal Coronaviruses

Coronaviruses (CoVs) are a group of enveloped positive-sense RNA viruses and can cause deadly diseases in animals and humans. Cell entry is the first and essential step of successful virus infection and can be divided into two ongoing steps: cell binding and membrane fusion. Over the past two decades, stimulated by the global outbreak of SARS-CoV and pandemic of SARS-CoV-2, numerous efforts have been made in the CoV research. As a result, significant progress has been achieved in our understanding of the cell entry process. Here, we review the current knowledge of this essential process, including the viral and host components involved in cell binding and membrane fusion, molecular mechanisms of their interactions, and the sites of virus entry. We highlight the recent findings of host restriction factors that inhibit CoVs entry. This knowledge not only enhances our understanding of the cell entry process, pathogenesis, tissue tropism, host range, and interspecies-transmission of CoVs but also provides a theoretical basis to design effective preventive and therapeutic strategies to control CoVs infection.

Aortic Thrombosis and Acute Limb Ischemia Secondary to COVID Hypercoagulability

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or coronavirus disease 2019 (COVID-19), first identified in December 2019 in Wuhan, China, has rapidly spread worldwide, is now a public health emergency, and has been declared a pandemic. While SARS-CoV-2 is known to cause significant pulmonary disease, ranging from pneumonia to acute respiratory distress syndrome (ARDS), various extrapulmonary manifestations of COVID-19 have also been reported. Growing evidence suggests that COVID-19 leads to a hypercoagulable state leading to micro and macro-vascular angiopathies. We present a case of an 80-year-old male without a previous history of prothrombotic disorders who developed descending aortic thrombosis, approximately 40% stenosis, at the level of the diaphragmatic hiatus and acute limb ischemia secondary to COVID-19 requiring emergent surgical intervention. After 12 days of persistent ischemic left lower extremity imaging despite thrombectomy, bypass, and therapeutic heparin, the patient's limb was deemed non-salvageable and underwent left above-knee amputation. Transthoracic echocardiogram revealed normal left ventricular function, moderate pulmonary hypertension, and no evidence of atrial septal defect, aortic root abnormalities, or intraventricular thrombi. Evaluation of autoimmune and inflammatory vasculitis was negative. While further study into the prothrombotic nature of this condition still needs to be pursued, the thromboembolic risk of COVID-19 represents an urgent need for appropriate anticoagulation for venous thrombosis. Arterial thrombosis requires other kinds of management to avoid the severe adverse effects of emboli and related ischemia. This current case highlights the need for randomized control trials testing different prophylactic strategies. Further evidence is also required for the role of amputation surgery when initial interventions for revascularization fail to restore blood flow.

Effectiveness of germicidal ultraviolet light to inactivate coronaviruses on personal protective equipment to reduce nosocomial transmission

OBJECTIVE

To circumvent the need for rationing personal protective equipment (PPE), we explored whether germicidal ultraviolet light (GUV) could be used to inactivate human coronaviruses on PPE, enabling safe reuse.

DESIGN

We performed a laboratory study to assess the ability of 2 commercially available portable GUV devices to inactivate 2 common cold coronaviruses (HCoV-229E and HCoV-OC43) and severe acute respiratory syndrome coronavirus virus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), on the surface of whole N95 respirators and coupons cut from those respirators. We experimentally contaminated N95 respirators with coronavirus cultures and then assessed viral inactivation after GUV exposure by plaque assay, the median tissue culture infectious dose (TCID50) assay, and quantitative reverse-transcriptase polymerase chain reaction (RT-PCR).

RESULTS

We found that GUV could efficiently inactivate coronaviruses on the surface of N95 masks, with an average reduction in viral titers of 5-log for HCoV-229E, 3-log for HCoV-OC43, and 5-log for SARS-CoV-2. In addition, the GUV susceptibility of HCoV-229E was similar on coupons and whole N95 respirators.

CONCLUSIONS

We demonstrate that diverse human coronaviruses, including SARS-CoV-2, are susceptible to GUV inactivation, and 2 scalable portable GUV devices were effective in inactivating coronaviruses on N95 respirators. Thus, GUV treatment with commercially scalable devices may be an effective method to decontaminate PPE, allowing their safe reuse.

Heparan Sulfate Proteoglycans in Viral Infection and Treatment: A Special Focus on SARS-CoV-2

Heparan sulfate proteoglycans (HSPGs) encompass a group of glycoproteins composed of unbranched negatively charged heparan sulfate (HS) chains covalently attached to a core protein. The complex HSPG biosynthetic machinery generates an extraordinary structural variety of HS chains that enable them to bind a plethora of ligands, including growth factors, morphogens, cytokines, chemokines, enzymes, matrix proteins, and bacterial and viral pathogens. These interactions translate into key regulatory activity of HSPGs on a wide range of cellular processes such as receptor activation and signaling, cytoskeleton assembly, extracellular matrix remodeling, endocytosis, cell-cell crosstalk, and others. Due to their ubiquitous expression within tissues and their large functional repertoire, HSPGs are involved in many physiopathological processes; thus, they have emerged as valuable targets for the therapy of many human diseases. Among their functions, HSPGs assist many viruses in invading host cells at various steps of their life cycle. Viruses utilize HSPGs for the attachment to the host cell, internalization, intracellular trafficking, egress, and spread. Recently, HSPG involvement in the pathogenesis of SARS-CoV-2 infection has been established. Here, we summarize the current knowledge on the molecular mechanisms underlying HSPG/SARS-CoV-2 interaction and downstream effects, and we provide an overview of the HSPG-based therapeutic strategies that could be used to combat such a fearsome virus.

Role of host factors in SARS-CoV-2 entry

The zoonotic transmission of highly pathogenic coronaviruses into the human population is a pressing concern highlighted by the ongoing SARS-CoV-2 pandemic. Recent work has helped to illuminate much about the mechanisms of SARS-CoV-2 entry into the cell, which determines host- and tissue-specific tropism, pathogenicity, and zoonotic transmission. Here we discuss current findings on the factors governing SARS-CoV-2 entry. We first reviewed key features of the viral spike protein (S) mediating fusion of the viral envelope and host cell membrane through binding to the SARS-CoV-2 receptor, angiotensin-converting enzyme 2. We then examined the roles of host proteases including transmembrane protease serine 2 and cathepsins in processing S for virus entry and the impact of this processing on endosomal and plasma membrane virus entry routes. We further discussed recent work on several host cofactors that enhance SARS-CoV-2 entry including Neuropilin-1, CD147, phosphatidylserine receptors, heparan sulfate proteoglycans, sialic acids, and C-type lectins. Finally, we discussed two key host restriction factors, i.e., interferon-induced transmembrane proteins and lymphocyte antigen 6 complex locus E, which can disrupt SARS-CoV-2 entry. The features of SARS-CoV-2 are presented in the context of other human coronaviruses, highlighting unique aspects. In addition, we identify the gaps in understanding of SARS-CoV-2 entry that will need to be addressed by future studies.

Network-based virus-host interaction prediction with application to SARS-CoV-2

COVID-19, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has quickly become a global health crisis since the first report of infection in December of 2019. However, the infection spectrum of SARS-CoV-2 and its comprehensive protein-level interactions with hosts remain unclear. There is a massive amount of underutilized data and knowledge about RNA viruses highly relevant to SARS-CoV-2 and proteins of their hosts. More in-depth and more comprehensive analyses of that knowledge and data can shed new light on the molecular mechanisms underlying the COVID-19 pandemic and reveal potential risks. In this work, we constructed a multi-layer virus-host interaction network to incorporate these data and knowledge. We developed a machine-learning-based method to predict virus-host interactions at both protein and organism levels. Our approach revealed five potential infection targets of SARS-CoV-2 and 19 highly possible interactions between SARS-CoV-2 proteins and human proteins in the innate immune pathway.

Amachawadi R, Dash AP, Yadav MP, Prasad KS, P S, Jain AS, Shivamallu C. COVID-19 PANDEMIC: A SYSTEMATIC REVIEW ON THE CORONAVIRUSES OF ANIMALS AND SARS-CoV-2

Coronaviruses (CoVs), classified into four genera, viz., alpha-, beta-, gamma-, and Delta- CoV, represent an important group of diverse transboundary pathogens that can infect a variety of mammalian and avian species including humans, animals, poultry, and non-poultry birds. CoVs primarily infect lung and gut epithelial cells, besides monocytes and macrophages. CoVs have high mutation rates causing changes in host specificity, tissue tropism, and mode of virus excretion and transmissions. The recent CoV zoonoses are SARS, MERS, and COVID-19 that are caused by the transmission of beta-CoVs of bats to humans. Recently, reverse zoonoses of the COVID-19 virus have been detected in dogs, tigers, and minks. Beta-CoV strains also infect bovine (BCoV) and canine species (CRCoV); both these beta-CoVs might have originated from a common ancestor. Despite the high genetic similarity between BCoV, CRCoV, and HCoV-OC43, these differ in species specificity. Alpha-CoV strains infect canine (CCoV), feline (FIPV), swine (TGEV and PEDV), and humans (HCoV229E and NL63). Six coronavirus species are known to infect and cause disease in pigs, seven in human beings, and two in dogs. The high mutation rate in CoVs is attributed to error-prone 3′-5′ exoribonuclease (NSP 14), and genetic recombination to template shift by the polymerase. The present compilation describes the important features of the CoVs and diseases caused in humans, animals, and birds that are essential in surveillance of diverse pool of CoVs circulating in nature, and monitoring interspecies transmission, zoonoses, and reverse zoonoses.

Bovine Coronavirus and the Associated Diseases

Coronaviruses (CoVs) possess the largest and most complex RNA genome (up to 32 kb) that encodes for 16 non-structural proteins regulating RNA synthesis and modification. Coronaviruses are known to infect a wide range of mammalian and avian species causing remarkably diverse disease syndromes. Variable tissue tropism and the ability to easily cross interspecies barriers are the well-known characteristics of certain CoVs. The 21st century epidemics of severe acute respiratory CoV (SARS-CoV), Middle East respiratory CoV and the ongoing SARS-CoV-2 pandemic further highlight these characteristics and emphasize the relevance of CoVs to the global public health. Bovine CoVs (BCoVs) are betacoronaviruses associated with neonatal calf diarrhea, and with winter dysentery and shipping fever in older cattle. Of interest, no distinct genetic or antigenic markers have been identified in BCoVs associated with these distinct clinical syndromes. In contrast, like other CoVs, BCoVs exist as quasispecies. Besides cattle, BCoVs and bovine-like CoVs were identified in various domestic and wild ruminant species (water buffalo, sheep, goat, dromedary camel, llama, alpaca, deer, wild cattle, antelopes, giraffes, and wild goats), dogs and humans. Surprisingly, bovine-like CoVs also cannot be reliably distinguished from BCoVs using comparative genomics. Additionally, there are historical examples of zoonotic transmission of BCoVs. This article will discuss BCoV pathogenesis, epidemiology, interspecies transmission, immune responses, vaccines, and diagnostics.

New Acaciin-Loaded Self-Assembled Nanofibers as MPro Inhibitors Against BCV as a Surrogate Model for SARS-CoV-2

BACKGROUND

SARS-COVID-2 has recently been one of the most life-threatening problems which urgently needs new therapeutic antiviral agents, especially those of herbal origin.

PURPOSE

The study aimed to load acaciin (ACA) into the new self-assembled nanofibers (NFs) followed by investigating their possible antiviral effect against bovine coronavirus (BCV) as a surrogate model for SARS-COV-2.

METHODS

ACA was identified using 1H-NMR and DEPT-Q 13C-NMR spectroscopy, the molecular docking study was performed using Autodock 4 and a modification of the traditional solvent injection method was applied for the synthesis of the biodegradable NFs. Different characterization techniques were used to inspect the formation of the NFs, which is followed by antiviral investigation against BCV as well as MTT assay using MDBK cells.

RESULTS

Core/shell NFs, ranging between 80-330 nm with tiny thorn-like branches, were formed which attained an enhanced encapsulation efficiency (97.5 ± 0.53%, P<0.05) and a dual controlled release (a burst release of 65% at 1 h and a sustained release up to >24 h). The antiviral investigation of the formed NFs revealed a significant inhibition of 98.88 ± 0.16% (P<0.05) with IC50 of 12.6 µM against BCV cells.

CONCLUSION

The results introduced a new, time/cost-saving strategy for the synthesis of biodegradable NFs without the need for electric current or hazardous cross-linking agents. Moreover, it provided an innovative avenue for the discovery of drugs of herbal origin for the fight against SARS-CoV-2 infection.

Respiratory RNA Viruses: How to Be Prepared for an Encounter with New Pandemic Virus Strains

The characteristics of the biology of influenza viruses and coronavirus that determine the implementation of the infectious process are presented. With provision for pathogenesis of infection possible effects of serine proteinase inhibitors, heparin, and inhibitors of heparan sulfate receptors in the prevention of cell contamination by viruses are examined. It has been determined that chelators of metals of variable valency and antioxidants should be used for the reduction of replicative activity of viruses and anti-inflammatory therapy. The possibility of a pH-dependent impairment of glycosylation of cellular and viral proteins was traced for chloroquine and its derivatives. The use of low-toxicity drugs as part of adjunct therapy increases the effectiveness of synthetic antiviral drugs and interferons and ensures the safety of baseline therapy.

Could Naturally Occurring Coronaviral Diseases in Animals Serve as Models for COVID-19? A Review Focusing on the Bovine Model

The current pandemic of COVID-19 has highlighted the importance of basic studies on coronaviruses (CoVs) in general, and severe acute respiratory syndrome CoV type 2 (SARS-CoV-2) in particular. CoVs have for long been studied in veterinary medicine, due to their impact on animal health and welfare, production, and economy. Several animal models using coronaviral disease in the natural host have been suggested. In this review, different animal models are discussed, with the main focus on bovine CoV (BCoV). BCoV is endemic in the cattle population worldwide and has been known and studied for several decades. SARS-CoV-2 and BCoV are both betacoronaviruses, where BCoV is highly similar to human coronavirus (HCoV) OC43, encompassing the same virus species (Betacoronavirus 1). BCoV causes respiratory and gastrointestinal disease in young and adult cattle. This review summarizes the current knowledge of the similarities and dissimilarities between BCoV and SARS-CoV-2, as well as discussing the usage of BCoV as a model for human CoVs, including SARS-CoV-2.

Kallikrein 13 serves as a priming protease during infection by the human coronavirus HKU1

Unlike SARS-CoV-2, the human coronavirus HKU1 normally causes relatively mild respiratory tract infections; however, it shares with SARS-CoV-2 the mechanism of using its surface spike (S) protein to enter target cells. Because the host receptor for HCoV-HKU1 is unknown, efforts to study the virus in cell culture systems have proved difficult. Milewska et al. found that knockout of the protease kallikrein 13 (KLK13) in human airway epithelial cells blocked their infection by HCoV-HKU1, that overexpression of KLK13 in nonpermissive cells enabled their infection by the virus, and that KLK13 cleaved the viral S protein. Together, these findings suggest that KLK13 is a priming enzyme for viral entry and may help to establish cell lines that can facilitate further investigation of the mechanism of viral pathogenesis.

Human coronavirus HKU1 (HCoV-HKU1) is associated with respiratory disease and is prevalent worldwide, but an in vitro model for viral replication is lacking. An interaction between the coronaviral spike (S) protein and its receptor is the primary determinant of tissue and host specificity; however, viral entry is a complex process requiring the concerted action of multiple cellular elements. Here, we found that the protease kallikrein 13 (KLK13) was required for the infection of human respiratory epithelial cells and was sufficient to mediate the entry of HCoV-HKU1 into nonpermissive RD cells. We also demonstrated the cleavage of the HCoV-HKU1 S protein by KLK13 in the S1/S2 region, suggesting that KLK13 is the priming enzyme for this virus. Together, these data suggest that protease distribution and specificity determine the tissue and cell specificity of the virus and may also regulate interspecies transmission.

Drawing Comparisons between SARS-CoV-2 and the Animal Coronaviruses

The COVID-19 pandemic, caused by a novel zoonotic coronavirus (CoV), SARS-CoV-2, has infected 46,182 million people, resulting in 1,197,026 deaths (as of 1 November 2020), with devastating and far-reaching impacts on economies and societies worldwide. The complex origin, extended human-to-human transmission, pathogenesis, host immune responses, and various clinical presentations of SARS-CoV-2 have presented serious challenges in understanding and combating the pandemic situation. Human CoVs gained attention only after the SARS-CoV outbreak of 2002-2003. On the other hand, animal CoVs have been studied extensively for many decades, providing a plethora of important information on their genetic diversity, transmission, tissue tropism and pathology, host immunity, and therapeutic and prophylactic strategies, some of which have striking resemblance to those seen with SARS-CoV-2. Moreover, the evolution of human CoVs, including SARS-CoV-2, is intermingled with those of animal CoVs. In this comprehensive review, attempts have been made to compare the current knowledge on evolution, transmission, pathogenesis, immunopathology, therapeutics, and prophylaxis of SARS-CoV-2 with those of various animal CoVs. Information on animal CoVs might enhance our understanding of SARS-CoV-2, and accordingly, benefit the development of effective control and prevention strategies against COVID-19.

Coronavirus Infection of the Central Nervous System: Animal Models in the Time of COVID-19

Naturally occurring coronaviral infections have been studied for several decades in the context of companion and production animals, and central nervous system involvement is a common finding, particularly in cats with feline infectious peritonitis (FIP). These companion and production animal coronaviruses have many similarities to recent human pandemic-associated coronaviruses such as SARS-CoV, MERS-CoV, and SARS-CoV2 (COVID-19). Neurological involvement is being increasingly recognized as an important clinical presentation in human COVID-19 patients, often associated with para-infectious processes, and potentially with direct infection within the CNS. Recent breakthroughs in the treatment of coronaviral infections in cats, including neurological FIP, have utilized antiviral drugs similar to those currently in human COVID-19 clinical trials. Differences in specific coronavirus and host factors are reflected in major variations in incidence and mechanisms of CNS coronaviral infection and pathology between species; however, broad lessons relating to treatment of coronavirus infection present within the CNS may be informative across species.

The past, present and future of RNA respiratory viruses: influenza and coronaviruses

Influenza virus and coronaviruses continue to cause pandemics across the globe. We now have a greater understanding of their functions. Unfortunately, the number of drugs in our armory to defend us against them is inadequate. This may require us to think about what mechanisms to address. Here, we review the biological properties of these viruses, their genetic evolution and antiviral therapies that can be used or have been attempted. We will describe several classes of drugs such as serine protease inhibitors, heparin, heparan sulfate receptor inhibitors, chelating agents, immunomodulators and many others. We also briefly describe some of the drug repurposing efforts that have taken place in an effort to rapidly identify molecules to treat patients with COVID-19. While we put a heavy emphasis on the past and present efforts, we also provide some thoughts about what we need to do to prepare for respiratory viral threats in the future.

Male Fertility and the COVID-19 Pandemic: Systematic Review of the Literature

PURPOSE

Since its discovery in December 2019, the novel coronavirus SARS-CoV-2 has spread globally, causing the current COVID-19 (coronavirus disease-19) pandemic. As there is an increase of infections in the male population, concerns have emerged about the potential impact of COVID-19 on male reproductive organs and male fertility. Therefore, this study systematically investigates the current evidence of SARS-CoV-2 impact on male reproduction and pregnancy outcomes, discussing them in light of the evidence published on other coronaviruses.

MATERIALS AND METHODS

Literature search was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 24 original articles were included for the analysis, investigating the effects of the infection on semen parameters, male reproductive hormones, and pregnancy outcomes. Further, a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis was conducted based on the available evidence linking the virus with male reproduction and conception.

RESULTS

Although there is limited data, viral mRNA has been identified in semen of infected men, with some evidence of altered seminal parameters. Low testosterone and dihydrotestosterone with raised luteinizing hormone has been reported as well as preterm delivery in pregnant women; however, data regarding vertical transmission remains contradictory and inconclusive.

CONCLUSIONS

The recent literature provides evidence that male gonads may be potentially vulnerable to SARS-CoV-2 infection, recommending caution to pregnant women and couples planning natural pregnancy or assisted reproduction.

Coronavirus Infections in Companion Animals: Virology, Epidemiology, Clinical and Pathologic Features

Coronaviruses are enveloped RNA viruses capable of causing respiratory, enteric, or systemic diseases in a variety of mammalian hosts that vary in clinical severity from subclinical to fatal. The host range and tissue tropism are largely determined by the coronaviral spike protein, which initiates cellular infection by promoting fusion of the viral and host cell membranes. Companion animal coronaviruses responsible for causing enteric infection include feline enteric coronavirus, ferret enteric coronavirus, canine enteric coronavirus, equine coronavirus, and alpaca enteric coronavirus, while canine respiratory coronavirus and alpaca respiratory coronavirus result in respiratory infection. Ferret systemic coronavirus and feline infectious peritonitis virus, a mutated feline enteric coronavirus, can lead to lethal immuno-inflammatory systemic disease. Recent human viral pandemics, including severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and most recently, COVID-19, all thought to originate from bat coronaviruses, demonstrate the zoonotic potential of coronaviruses and their potential to have devastating impacts. A better understanding of the coronaviruses of companion animals, their capacity for cross-species transmission, and the sharing of genetic information may facilitate improved prevention and control strategies for future emerging zoonotic coronaviruses. This article reviews the clinical, epidemiologic, virologic, and pathologic characteristics of nine important coronaviruses of companion animals.

Animal coronaviruses and SARS-CoV-2

COVID-19 is a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It has rapidly spread to 216 countries and territories since first outbreak in December of 2019, posing a substantial economic losses and extraordinary threats to the public health worldwide. Although bats have been suggested as the natural host of SARS-CoV-2, transmission chains of this virus, role of animals during cross-species transmission, and future concerns remain unclear. Diverse animal coronaviruses have extensively been studied since the discovery of avian coronavirus in 1930s. The current article comprehensively reviews and discusses the current understanding about animal coronaviruses and SARS-CoV-2 for their emergence, transmission, zoonotic potential, alteration of tissue/host tropism, evolution, status of vaccines and surveillance. This study aims at providing guidance for control of COVID-19 and preventative strategies for possible future outbreaks of zoonotic coronavirus via cross-species transmission.

Evidence for SARS-CoV-2 Infection of Animal Hosts

COVID-19 is the first known pandemic caused by a coronavirus, SARS-CoV-2, which is the third virus in the family Coronaviridae to cause fatal infections in humans after SARS-CoV and MERS-CoV. Animals are involved in the COVID-19 pandemic. This review summarizes the role of animals as reservoirs, natural hosts and experimental models. SARS-CoV-2 originated from animal reservoir, most likely bats and/or pangolins. Anthroponotic transmission has been reported in cats, dogs, tigers, lions and minks. As of now, there is no a strong evidence for natural animal-to-human transmission or sustained animal-to-animal transmission of SARS-CoV-2. Experimental infections conducted by several research groups have shown that monkeys, hamsters, ferrets, cats, tree shrews, transgenic mice and fruit bats were permissive, while dogs, pigs and poultry were resistant. There is an urgent need to understand the zoonotic potential of different viruses in animals, particularly in bats, before they transmit to humans. Vaccines or antivirals against SARS-CoV-2 should be evaluated not only for humans, but also for the protection of companion animals (particularly cats) and susceptible zoo and farm animals.

Coronaviridae-Old friends, new enemy!

Coronaviridae is a family of single‐stranded positive enveloped RNA viruses. This article aimed to review the history of these viruses in the last 60 years since their discovery to understand what lessons can be learned from the past. A review of the PubMed database was carried out, describing taxonomy, classification, virology, genetic recombination, host adaptation, and main symptoms related to each type of virus. SARS‐CoV‐2 is responsible for the ongoing global pandemic, and SARS‐CoV and MERS‐CoV were responsible for causing severe respiratory illness and regional epidemics in the past while the four other strains of CoVs (229‐E OC43, NL63, and HKU1) circulate worldwide and normally only cause mild upper respiratory tract infections. Given the enormous diversity of coronavirus viruses in wildlife and their continuous evolution and adaptation to humans, future outbreaks would undoubtedly occur. Restricting or banning all trade in wild animals in wet markets would be a necessary measure to reduce future zoonotic infections.

The Biology of Lactoferrin, an Iron-Binding Protein That Can Help Defend Against Viruses and Bacteria

Lactoferrin is a nutrient classically found in mammalian milk. It binds iron and is transferred via a variety of receptors into and between cells, serum, bile, and cerebrospinal fluid. It has important immunological properties, and is both antibacterial and antiviral. In particular, there is evidence that it can bind to at least some of the receptors used by coronaviruses and thereby block their entry. Of importance are Heparan Sulfate Proteoglycans (HSPGs) and the host receptor angiotensin-converting enzyme 2 (ACE2), as based on other activities lactoferrin might prevent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from attaching to the host cells. Lactoferrin (and more specifically enteric-coated LF because of increased bioavailability) may consequently be of preventive and therapeutic value during the present COVID-19 pandemic.

Acute limb ischemia in patients with COVID-19 pneumonia

Objective

The aim of our study was to determine the incidence, characteristics, and clinical outcomes of patients with the novel coronavirus (COVID-19) infection who had presented with and been treated for acute limb ischemia (ALI) during the 2020 coronavirus pandemic.

Methods

We performed a single-center, observational cohort study. The data from all patients who had tested positive for COVID-19 and had presented with ALI requiring urgent operative treatment were collected in a prospectively maintained database. For the present series, successful revascularization of the treated arterial segment was defined as the absence of early (<30 days) re-occlusion or major amputation or death within 24 hours. The primary outcomes were successful revascularization, early (≤30 days) and late (≥30 days) survival, postoperative (≤30 days) complications, and limb salvage.

Results

We evaluated the data from 20 patients with ALI who were positive for COVID-19. For the period from January to March, the incidence rate of patients presenting with ALI in 2020 was significantly greater than that for the same months in 2019 (23 of 141 [16.3%] vs 3 of 163 [1.8%]; P < .001)]. Of the 20 included patients, 18 were men (90%) and two were women (10%). Their mean age was 75 ± 9 years (range, 62-95 years). All 20 patients already had a diagnosis of COVID-19 pneumonia. Operative treatment was performed in 17 patients (85%). Revascularization was successful in 12 of the 17 (70.6%). Although successful revascularization was not significantly associated with the postoperative use of intravenous heparin (64.7% vs 83.3%; P = .622), no patient who had received intravenous heparin required reintervention. Of the 20 patients, eight (40%) had died in the hospital. The patients who had died were significantly older (81 ± 10 years vs 71 ± 5 years; P = .008). The use of continuous postoperative systemic heparin infusion was significantly associated with survival (0% vs 57.1%; P = .042).

Conclusions

In our preliminary experience, the incidence of ALI has significantly increased during the COVID-19 pandemic in the Italian Lombardy region. Successful revascularization was lower than expected, which we believed was due to a virus-related hypercoagulable state. The use of prolonged systemic heparin might improve surgical treatment efficacy, limb salvage, and overall survival.