SARS-CoV-2-Mediated Lung Edema and Replication Are Diminished by Cystic Fibrosis Transmembrane Conductance Regulator Modulators

Identification of potential antiviral compounds from Egyptian Red Sea soft corals against Middle East respiratory syndrome coronavirus

The ongoing threat of Middle East respiratory syndrome coronavirus (MERS-CoV) underscores the importance of developing effective antiviral treatments. Current research was conducted to identify potential antiviral compounds from soft corals: Sinularia leptoclados, Sarcophyton ehrenbergi, Nephthea sp., Sarcophyton glaucum and Sarcophyton regulare. The antiviral activities of soft corals extracts were evaluated against MERS-CoV. Gas chromatography-mass spectrometry (GC-MS) was used to identify bioactive compounds. The molecular docking was performed to examine the identified compounds for their binding potentials towards three pathogenic factors of MERS-CoV: main protease, spike and non-structural protein 16/10 complex. The methanolic extract of soft coral Sarcophyton regulare exhibited the most promising activity with 50% inhibitory concentration (IC50) of 4.29 µg/ml and selective index (SI) of 112.2. Among the identified compounds in the active fraction, the molecular docking showed that two fatty acid esters: hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester and octadecanoic acid, 2-hydroxy-1 (hydroxymethyl) ethyl ester had promising docking scores.

Interaction between SARS-CoV PBM and Cellular PDZ Domains Leading to Virus Virulence

The interaction between SARS-CoV PDZ-binding motifs (PBMs) and cellular PDZs is responsible for virus virulence. The PBM sequence present in the 3a and envelope (E) proteins of SARS-CoV can potentially bind to over 400 cellular proteins containing PDZ domains. The role of SARS-CoV 3a and E proteins was studied. SARS-CoVs, in which 3a-PBM and E-PMB have been deleted (3a-PBM-/E-PBM-), reduced their titer around one logarithmic unit but still were viable. In addition, the absence of the E-PBM and the replacement of 3a-PBM with that of E did not allow the rescue of SARS-CoV. E protein PBM was necessary for virulence, activating p38-MAPK through the interaction with Syntenin-1 PDZ domain. However, the presence or absence of the homologous motif in the 3a protein, which does not bind to Syntenin-1, did not affect virus pathogenicity. Mutagenesis analysis and in silico modeling were performed to study the extension of the PBM of the SARS-CoV E protein. Alanine and glycine scanning was performed revealing a pair of amino acids necessary for optimum virus replication. The binding of E protein with the PDZ2 domain of the Syntenin-1 homodimer induced conformational changes in both PDZ domains 1 and 2 of the dimer.

Genetic variants in ATP2B2 as risk factors for mortality in patients unrelated but not associated with families with severe COVID-19

Introduction

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of Coronavirus Disease 2019 (COVID-19). The disease has a wide range of clinical manifestations, from asymptomatic to severe. Ancestral contribution, sex, immune response, and genetic factors influence the presentation of the disease. The objective of the present study was to validate these genetic variants in patients with severe COVID-19 who died and in survivor patients. Methods: Single nucleotide variants (SNVs) in six genes: ATPase plasma membrane Ca2+ transporting 2 (ATP2B2), transmembrane serine protease 2 (TMPRSS2), dedicator of cytokinesis 2 (DOCK2), (interferon alpha and beta receptor subunit 2) IFNAR2, tumor necrosis factor receptor superfamily, member 1A (TNFRSF1A), and tumor necrosis factor receptor superfamily, member 1B (TNFRSF1B), were explored in two groups: the first consisted of severe COVID-19-related patients (familial cases from 58 families, n = 130), and the second group of unrelated severe COVID-19 patients (n = 1045). In each study group, death was evaluated as the outcome.

Results

In non-related patients with severe COVID-19, carriers of GG genotype (rs2289274) in the ATP2B2 gene showed a high-risk probability of non-surviving (OR = 1.43). Survival analysis to 75 days indicates that carriers of GG have a higher risk than GA or AA genotypes (p = 0.0059). The haplotype GG (rs2289273-rs2289274) in ATP2B2 was found to be associated with a high risk of death in severe non-related COVID-19 patients. No significant associations were found between severe COVID-19-related patients and SNVs in ATP2B2, TMPRSS2, DOCK2, IFNAR2, TNFRSF1A, or TNFRSF1B.

Conclusions

Unrelated patients with severe COVID-19 that carry the GG genotype (rs2289274) in ATP2B2 showed a high death risk. Survival analysis to 75 days indicates that carriers of GG have a higher risk of non-survival compared to GA or AA genotypes.

Comparative Pathogenesis of Severe Acute Respiratory Syndrome Coronaviruses

Over the last two decades the world has witnessed the global spread of two genetically related highly pathogenic coronaviruses, severe acute respiratory syndrome coronavirus (SARS-CoV) and SARS-CoV-2. However, the impact of these outbreaks differed significantly with respect to the hospitalizations and fatalities seen worldwide. While many studies have been performed recently on SARS-CoV-2, a comparative pathogenesis analysis with SARS-CoV may further provide critical insights into the mechanisms of disease that drive coronavirus-induced respiratory disease. In this review, we comprehensively describe clinical and experimental observations related to transmission and pathogenesis of SARS-CoV-2 in comparison with SARS-CoV, focusing on human, animal, and in vitro studies. By deciphering the similarities and disparities of SARS-CoV and SARS-CoV-2, in terms of transmission and pathogenesis mechanisms, we offer insights into the divergent characteristics of these two viruses. This information may also be relevant to assessing potential novel introductions of genetically related highly pathogenic coronaviruses.

SARS-CoV-2 ORF3a Protein as a Therapeutic Target against COVID-19 and Long-Term Post-Infection Effects

The COVID-19 pandemic caused by SARS-CoV-2 has posed unparalleled challenges due to its rapid transmission, ability to mutate, high mortality and morbidity, and enduring health complications. Vaccines have exhibited effectiveness, but their efficacy diminishes over time while new variants continue to emerge. Antiviral medications offer a viable alternative, but their success has been inconsistent. Therefore, there remains an ongoing need to identify innovative antiviral drugs for treating COVID-19 and its post-infection complications. The ORF3a (open reading frame 3a) protein found in SARS-CoV-2, represents a promising target for antiviral treatment due to its multifaceted role in viral pathogenesis, cytokine storms, disease severity, and mortality. ORF3a contributes significantly to viral pathogenesis by facilitating viral assembly and release, essential processes in the viral life cycle, while also suppressing the body's antiviral responses, thus aiding viral replication. ORF3a also has been implicated in triggering excessive inflammation, characterized by NF-κB-mediated cytokine production, ultimately leading to apoptotic cell death and tissue damage in the lungs, kidneys, and the central nervous system. Additionally, ORF3a triggers the activation of the NLRP3 inflammasome, inciting a cytokine storm, which is a major contributor to the severity of the disease and subsequent mortality. As with the spike protein, ORF3a also undergoes mutations, and certain mutant variants correlate with heightened disease severity in COVID-19. These mutations may influence viral replication and host cellular inflammatory responses. While establishing a direct link between ORF3a and mortality is difficult, its involvement in promoting inflammation and exacerbating disease severity likely contributes to higher mortality rates in severe COVID-19 cases. This review offers a comprehensive and detailed exploration of ORF3a's potential as an innovative antiviral drug target. Additionally, we outline potential strategies for discovering and developing ORF3a inhibitor drugs to counteract its harmful effects, alleviate tissue damage, and reduce the severity of COVID-19 and its lingering complications.

The impact of SARS-CoV-2 infection in patients with cystic fibrosis undergoing CFTR channel modulators treatment: a literature review

Several risk factors for Coronavirus-2019 (COVID-19) disease have been highlighted in clinical evidence. Among the various risk factors are advanced age, metabolic illness such as diabetes, heart disease, and diseases of the respiratory system. Cystic Fibrosis (CF) is a rare disease with autosomal recessive transmission, characterised by a lack of synthesis of the CFTR channel protein, and multi-organ clinical symptoms mainly affecting the respiratory tract with recurrent pulmonary exacerbations. In view of the pathophysiological mechanisms, CF disease should be in theory considered a risk factor for SARS-CoV2 or severe COVID-19. However, recent clinical evidence seems to point in the opposite direction, suggesting that CF could be a protective factor against severe COVID-19. Possibly, the lack of presence or function of the CFTR channel protein could be linked to the expression of the membrane glycoprotein ACE-2, a key enzyme for the endocellular penetration of SARS-CoV-2 and related to the pathophysiology of COVID-19 disease. Furthermore, CFTR channel modulating agents could indirectly influence the expression of ACE-2, playing an important role in restoring the proper functioning of mucociliary clearance and the pulmonary microbiome in the host response to SARS-CoV-2 infection. In this review, the authors attempt to shed light on these important associations of issues that are not yet fully elucidated.

Distinct motifs in the E protein are required for SARS-CoV-2 virus particle formation and lysosomal deacidification in host cells

IMPORTANCE

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), the virus responsible for coronavirus disease 2019 (COVID-19), has caused a global public health crisis. The E protein, a structural protein found in this virus particle, is also known to be a viroporin. As such, it forms oligomeric ion channels or pores in the host cell membrane. However, the relationship between these two functions is poorly understood. In this study, we showed that the roles of E protein in virus particle and viroporin formation are distinct. This study contributes to the development of drugs that inhibit SARS-CoV-2 virus particle formation. Additionally, we designed a highly sensitive and high-throughput virus-like particle detection system using the HiBiT tag, which is a useful tool for studying the release of SARS-CoV-2.

Cell type dependent stability and virulence of a recombinant SARS-CoV-2, and engineering of a propagation deficient RNA replicon to analyze virus RNA synthesis

Engineering of reverse genetics systems for newly emerged viruses allows viral genome manipulation, being an essential tool for the study of virus life cycle, virus-host interactions and pathogenesis, as well as for the development of effective antiviral strategies. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emergent human coronavirus that has caused the coronavirus disease (COVID-19) pandemic. The engineering of a full-length infectious cDNA clone and a fluorescent replicon of SARS-CoV-2 Wuhan-Hu-1, using a bacterial artificial chromosome, is reported. Viral growth and genetic stability in eleven cell lines were analyzed, showing that both VeroE6 cells overexpressing transmembrane serin protease 2 (TMPRSS2) and human lung derived cells resulted in the optimization of a cell system to preserve SARS-CoV-2 genetic stability. The recombinant SARS-CoV-2 virus and a point mutant expressing the D614G spike protein variant were virulent in a mouse model. The RNA replicon was propagation-defective, allowing its use in BSL-2 conditions to analyze viral RNA synthesis. The SARS-CoV-2 reverse genetics systems developed constitute a useful tool for studying the molecular biology of the virus, the development of genetically defined vaccines and to establish systems for antiviral compounds screening.

The Envelope (E) Protein of SARS-CoV-2 as a Pharmacological Target

The COVID-19 pandemic caused by the SARS-CoV-2 virus is still a global health concern. Several spike (S) protein-based vaccines have been developed that efficiently protect the human population against severe forms of COVID-19. However, some SARS-CoV-2 variants of concern (VOCs) have emerged that evade the protective effect of vaccine-induced antibodies. Therefore, efficient and specific antiviral treatments to control COVID-19 are indispensable. To date, two drugs have been approved for mild COVID-19 treatment; nevertheless, more drugs, preferably broad-spectrum and ready-to-use therapeutic agents for new pandemics, are needed. Here, I discuss the PDZ-dependent protein-protein interactions of the viral E protein with host proteins as attractive alternatives for the development of antivirals against coronavirus.

Host Response of Syrian Hamster to SARS-CoV-2 Infection including Differences with Humans and between Sexes

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the importance of having proper tools and models to study the pathophysiology of emerging infectious diseases to test therapeutic protocols, assess changes in viral phenotypes, and evaluate the effects of viral evolution. This study provided a comprehensive characterization of the Syrian hamster (Mesocricetus auratus) as an animal model for SARS-CoV-2 infection using different approaches (description of clinical signs, viral load, receptor profiling, and host immune response) and targeting four different organs (lungs, intestine, brain, and PBMCs). Our data showed that both male and female hamsters were susceptible to the infection and developed a disease similar to the one observed in patients with COVID-19 that included moderate to severe pulmonary lesions, inflammation, and recruitment of the immune system in the lungs and at the systemic level. However, all animals recovered within 14 days without developing the severe pathology seen in humans, and none of them died. We found faint evidence for intestinal and neurological tropism associated with the absence of lesions and a minimal host response in intestines and brains, which highlighted another crucial difference with the multiorgan impairment of severe COVID-19. When comparing male and female hamsters, we observed that males sustained higher viral RNA shedding and replication in the lungs, suffered from more severe symptoms and histopathological lesions, and triggered higher pulmonary inflammation. Overall, these data confirmed the Syrian hamster as a suitable model for mild to moderate COVID-19 and reflected sex-related differences in the response against the virus observed in humans.