Molecular dynamics analysis of N-acetyl-D-glucosamine against specific SARS-CoV-2's pathogenicity factors.

The causative agent of the pandemic identified as SARS-CoV-2 leads to a severe respiratory illness similar to SARS and MERS with fever, cough, and shortness of breath symptoms and severe cases that can often be fatal. In our study, we report our findings based on molecular docking analysis which could be the new effective way for controlling the SARS-CoV-2 virus and additionally, another manipulative possibilities involving the mimicking of immune system as occurred during the bacterial cell recognition system. For this purpose, we performed molecular docking using computational biology techniques on several SARS-CoV-2 proteins that are responsible for its pathogenicity against N-acetyl-D-glucosamine. A similar molecular dynamics analysis has been carried out on both SARS-CoV-2 and anti-Staphylococcus aureus neutralizing antibodies to establish the potential of N-acetyl-D-glucosamine which likely induces the immune response against the virus. The results of molecular dynamic analysis have confirmed that SARS-CoV-2 spike receptor-binding domain (PDB: 6M0J), RNA-binding domain of nucleocapsid phosphoprotein (PDB: 6WKP), refusion SARS-CoV-2 S ectodomain trimer (PDB: 6X79), and main protease 3clpro at room temperature (PDB: 7JVZ) could bind with N-acetyl-D-glucosamine that these proteins play an important role in SARS-CoV-2's infection and evade the immune system. Moreover, our molecular docking analysis has supported a strong protein-ligand interaction of N-acetyl-D-glucosamine with these selected proteins. Furthermore, computational analysis against the D614G mutant of the virus has shown that N-acetyl-D-glucosamine affinity and its binding potential were not affected by the mutations occurring in the virus' receptor binding domain. The analysis on the affinity of N-acetyl-D-glucosamine towards human antibodies has shown that it could potentially bind to both SARS-CoV-2 proteins and antibodies based on our predictive modelling work. Our results confirmed that N-acetyl-D-glucosamine holds the potential to inhibit several SARS-CoV-2 proteins as well as induce an immune response against the virus in the host.

Pathogenic perspective of missense mutations of ORF3a protein of SARS-CoV-2.

One of the most important proteins for COVID-19 pathogenesis in SARS-CoV-2 is the ORF3a which is the largest accessory protein among others coded by the SARS-CoV-2 genome. The major roles of the protein include virulence, infectivity, ion channel activity, morphogenesis, and virus release. The coronavirus, SARS-CoV-2 is mutating rapidly, therefore, critical study of mutations in ORF3a is certainly important from the pathogenic perspective. Here, a sum of 175 non-synonymous mutations in the ORF3a of SARS-CoV-2 were identified from 7194 complete genomes of SARS-CoV-2 available from NCBI database. Effects of these mutations on structural stability, and functions of ORF3a were also studied. Broadly, three different classes of mutations, such as neutral, disease, and mixed (neutral and disease) types of mutations were observed. Consecutive phenomena of mutations in ORF3a protein were studied based on the timeline of detection of the mutations. Considering the amino acid compositions of the ORF3a protein, twenty clusters were detected using the K-means clustering method. The present findings on 175 novel mutations of ORF3a proteins will extend our knowledge on ORF3a, a vital accessory protein in SARS-CoV-2, to enlighten the pathogenicity of this life-threatening virus.

SARS-CoV-2-specific virulence factors in COVID-19.

The paucity of knowledge about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific virulence factors has greatly hampered the therapeutic management of patients with coronavirus disease 2019 (COVID-19). Recently, a cluster of studies appeared, which presented empirical evidence for SARS-CoV-2-specific virulence factors that can explain key elements of COVID-19 pathology. These studies unravel multiple structural and nonstructural specifics of SARS-CoV-2, such as a unique FURIN cleavage site, papain-like protease (SCoV2-PLpro), ORF3b and nonstructural proteins, and dynamic conformational changes in the structure of spike protein during host cell fusion, which give it an edge in infectivity and virulence over previous coronaviruses causing pandemics. Investigators provided robust evidence that SARS-CoV-2-specific virulence factors may have an impact on viral infectivity and transmissibility and disease severity as well as the development of immunity against the infection, including response to the vaccines. In this article, we are presenting a summarized account of the newly reported studies.

Novel Immunoglobulin Domain Proteins Provide Insights into Evolution and Pathogenesis of SARS-CoV-2-Related Viruses.

A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was recently identified as the causative agent for the coronavirus disease 2019 (COVID-19) outbreak that has generated a global health crisis. We use a combination of genomic analysis and sensitive profile-based sequence and structure analysis to understand the potential pathogenesis determinants of this virus. As a result, we identify several fast-evolving genomic regions that might be at the interface of virus-host interactions, corresponding to the receptor binding domain of the Spike protein, the three tandem Macro fold domains in ORF1a, and the uncharacterized protein ORF8. Further, we show that ORF8 and several other proteins from alpha- and beta-CoVs belong to novel families of immunoglobulin (Ig) proteins. Among them, ORF8 is distinguished by being rapidly evolving, possessing a unique insert, and having a hypervariable position among SARS-CoV-2 genomes in its predicted ligand-binding groove. We also uncover numerous Ig domain proteins from several unrelated metazoan viruses, which are distinct in sequence and structure but share comparable architectures to those of the CoV Ig domain proteins. Hence, we propose that SARS-CoV-2 ORF8 and other previously unidentified CoV Ig domain proteins fall under the umbrella of a widespread strategy of deployment of Ig domain proteins in animal viruses as pathogenicity factors that modulate host immunity. The rapid evolution of the ORF8 Ig domain proteins points to a potential evolutionary arms race between viruses and hosts, likely arising from immune pressure, and suggests a role in transmission between distinct host species.IMPORTANCE The ongoing COVID-19 pandemic strongly emphasizes the need for a more complete understanding of the biology and pathogenesis of its causative agent SARS-CoV-2. Despite intense scrutiny, several proteins encoded by the genomes of SARS-CoV-2 and other SARS-like coronaviruses remain enigmatic. Moreover, the high infectivity and severity of SARS-CoV-2 in certain individuals make wet-lab studies currently challenging. In this study, we used a series of computational strategies to identify several fast-evolving regions of SARS-CoV-2 proteins which are potentially under host immune pressure. Most notably, the hitherto-uncharacterized protein encoded by ORF8 is one of them. Using sensitive sequence and structural analysis methods, we show that ORF8 and several other proteins from alpha- and beta-coronavirus comprise novel families of immunoglobulin domain proteins, which might function as potential immune modulators to delay or attenuate the host immune response against the viruses.