Molecular features similarities between SARS-CoV-2, SARS, MERS and key human genes could favour the viral infections and trigger collateral effects

Flow cytometric analysis of the SARS coronavirus 2 antibodies in human plasma

COVID-19 is an infectious disease caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2). Anti-SARS-CoV-2 antibodies can provide information on patient immunity, identify asymptomatic patients, and track the spread of COVID-19. Efforts have been made to develop methods to detect anti-SARS-CoV-2 antibodies in humans. Here, we describe a flow cytometric assay for the simultaneous detection of anti-SARS-CoV-2 IgG and IgM in human plasma. To assess the antibody response against the different SARS-CoV-2 structural proteins, five viral recombinant proteins, including spike protein subunit 1 (S1), N-terminal domain of S1 (S1A), spike receptor-binding domain (RBD), spike protein subunit 2 (S2), and nucleocapsid protein (N), were generated. A comparison of the antibody profiles detected by the assay with plasma from 100 healthy blood donors collected prior to the COVID-19 pandemic and plasma from 100 virologically confirmed COVID-19 patients demonstrated a clear discrimination between the two groups. Among the COVID-19 patients, the antibody responses for the viral proteins, as determined by their prevalence, were anti-RBD IgG = anti-N IgG > anti-S1 IgG > anti-S1A IgG > anti-S2 IgG, and anti-RBD IgM > anti-S1 IgM > anti-N IgM > anti-S2 IgM. The prevalence of anti-SARS-CoV-2 IgG and IgM was not associated with sex, age, race, days after the onset of symptoms, or severity of illness, except for a higher prevalence of anti-S2 IgG being observed in men than in women. The levels of anti-RBD IgG were higher in patients 65 years and older and in patients who had severe symptoms. Similarly, patients who had severe symptoms exhibited higher levels of anti-S1 and anti-S1A IgG than patients who had mild or moderate symptoms. The levels of anti-RBD IgM tended to be higher in men but did not differ among age, race, days after the onset of symptoms, or severity of illness. Our study indicates that the flow cytometric assay, especially using RBD as target antigen, can be used to detect simultaneously anti-SARS-CoV-2 IgG and IgM antibodies in human plasma.

Establishment of a Yeast Two-Hybrid-Based High-Throughput Screening Model for Selection of SARS-CoV-2 Spike-ACE2 Interaction Inhibitors

The recent coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has exerted considerable impact on global health. To prepare for rapidly mutating viruses and for the forthcoming pandemic, effective therapies targeting the critical stages of the viral life cycle need to be developed. Viruses are dependent on the interaction between the receptor-binding domain (RBD) of the viral Spike (S) protein (S-RBD) and the angiotensin-converting enzyme 2 (ACE2) receptor to efficiently establish infection and the following replicate. Targeting this interaction provides a promising strategy to inhibit the entry process of the virus, which in turn has both preventive and therapeutic effects. In this study, we developed a robust and straightforward assay based on the Yeast-Two Hybrid system (Y2H) for identifying inhibitors targeting the S-RBD-ACE2 interaction of SARS-CoV-2. Through high-throughput screening, two compounds were identified as potential entry inhibitors. Among them, IMB-1C was superior in terms of pseudovirus entry inhibition and toxicity. It could bind to both ACE2 and S-RBD and induce conformational change in the S-RBD+ACE2 complex. This is the first study to verify the feasibility of utilizing the Y2H system to discover potent SARS-CoV-2 inhibitors targeting the receptor recognition stage. This approach may also be applied in the discovery of other virus receptor recognition inhibitors.

Genomic analysis of severe COVID-19 considering or not asthma comorbidity: GWAS insights from the BQC19 cohort

BACKGROUND

The severity of COVID-19 is influenced by various factors including the presence of respiratory diseases. Studies have indicated a potential relationship between asthma and COVID-19 severity.

OBJECTIVE

This study aimed to conduct a genome-wide association study (GWAS) to identify genetic and clinical variants associated with the severity of COVID-19, both among patients with and without asthma.

METHODS

We analyzed data from 2131 samples sourced from the Biobanque québécoise de la COVID-19 (BQC19), with 1499 samples from patients who tested positive for COVID-19. Among these, 1110 exhibited mild-to-moderate symptoms, 389 had severe symptoms, and 58 had asthma. We conducted a comparative analysis of clinical data from individuals in these three groups and GWAS using a logistic regression model. Phenotypic data analysis resulted in the refined covariates integrated into logistic models for genetic studies.

RESULTS

Considering a significance threshold of 1 × 10-6, seven genetic variants were associated with severe COVID-19. These variants were located proximal to five genes: sodium voltage-gated channel alpha subunit 1 (SCN10A), desmoplakin (DSP), RP1 axonemal microtubule associated (RP1), IGF like family member 1 (IGFL1), and docking protein 5 (DOK5). The GWAS comparing individuals with severe COVID-19 with asthma to those without asthma revealed four genetic variants in transmembrane protein with EGF like and two follistatin like domains 2 (TMEFF2) and huntingtin interacting protein-1 (HIP1) genes.

CONCLUSION

This study provides significant insights into the genetic profiles of patients with severe forms of the disease, whether accompanied by asthma or not. These findings enhance our comprehension of the genetic factors that affect COVID-19 severity.

KEY MESSAGES

Seven genetic variants were associated with the severe form of COVID-19; Four genetic variants were associated with the severe form of COVID-19 in individuals with comorbid asthma; These findings help define the genetic component of the severe form of COVID-19 in relation to asthma as a comorbidity.

Flow injection analysis coupled with photoelectrochemical immunoassay for simultaneous detection of anti-SARS-CoV-2-spike and anti-SARS-CoV-2-nucleocapsid antibodies in serum samples

A thin-layer flow cell of low internal volume (12 μL) is incorporated in a flow injection analysis (FIA) system for simultaneous and real-time photoelectrochemical (PEC) immunoassay of anti-SARS-CoV-2 spike 1 (S1) and anti-SARS-CoV-2 nucleocapsid (N) antibodies. Covalent linkage of S1 and N proteins to two separate polyethylene glycol (PEG)-covered gold nanoparticles (AuNPs)/TiO2 nanotube array (NTA) electrodes affords 10 consecutive analyses with surface regenerations in between. An indium tin oxide (ITO) allows visible light to impinge onto the two electrodes. The detection limits for anti-S1 and anti-N antibodies were estimated to be 177 and 97 ng mL-1, respectively. Such values compare well with those achieved with other reported methods and satisfy the requirement for screening convalescent patients with low antibody levels. Additionally, our method exhibits excellent intra-batch (RSD = 1.3%), inter-batch (RSD = 3.4%), intra-day (RSD = 1.0%), and inter-day (RSD = 1.6%) reproducibility. The obviation of an enzyme label and continuous analysis markedly decreased the assay cost and duration, rendering this method cost-effective. The excellent anti-fouling property of PEG enables accuracy validation by comparing our PEC immunoassays of patient sera to those of ELISA. In addition, the simultaneous detection of two antibodies holds great potential in disease diagnosis and immunity studies.

Understanding the role of conserved proline and serine residues in the SARS-CoV-2 spike cleavage sites in the virus entry, fusion, and infectivity

The spike (S) glycoprotein of the SARS-CoV-2 virus binds to the host cell receptor and promotes the virus's entry into the target host cell. This interaction is primed by host cell proteases like furin and TMPRSS2, which act at the S1/S2 and S2´ cleavage sites, respectively. Both cleavage sites have serine or proline residues flanking either the single or polybasic region and were found to be conserved in coronaviruses. Unravelling the effects of these conserved residues on the virus entry and infectivity might facilitate the development of novel therapeutics. Here, we have investigated the role of the conserved serine and proline residues in the SARS-CoV-2 spike mediated entry, fusogenicity, and viral infectivity by using the HIV-1/spike-based pseudovirus system. A conserved serine residue mutation to alanine (S2´S-A) at the S2´ cleavage site resulted in the complete loss of spike cleavage. Exogenous treatment with trypsin or overexpression of TMPRSS2 protease could not rescue the loss of spike cleavage and biological activity. The S2´S-A mutant showed no significant responses against E-64d, TMPRSS2 or other relevant inhibitors. Taken together, serine at the S2´ site in the spike protein was indispensable for spike protein cleavage and virus infectivity. Thus, novel interventions targeting the conserved serine at the S2´ cleavage site should be explored to reduce severe disease caused by SARS-CoV-2-and novel emerging variants.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03749-y.

COVID infection in 4 steps: Thermodynamic considerations reveal how viral mucosal diffusion, target receptor affinity and furin cleavage act in concert to drive the nature and degree of infection in human COVID-19 disease

We have developed a mechanistic model of SARS-CoV-2 and SARS-CoV infection, exploring the relationship between the viral diffusion in the mucosa and viral affinity for the angiotensin converting enzyme 2 (ACE2) target. Utilising the structural similarity of SARS-CoV and SARS-CoV-2 and a shared viral target receptor (ACE2), but a dramatic difference in upper or lower respiratory tract infectivity, we were able to generate insights into the linkage of mucosal diffusion and target receptor affinity in determining the pathophysiological pathways of these two viruses. Our analysis reveals that for SARS-CoV-2 the higher affinity of ACE2 binding, the faster and more complete the mucosal diffusion in its transport from the upper airway to the region of the ACE2 target on the epithelium. This diffusional process is essential for the presentation of this virus to the furin catalysed highly efficient entry and infection process in the upper respiratory tract epithelial cells. A failure of SARS-CoV to follow this path is associated with lower respiratory tract infection and decreased infectivity. Thus, our analysis supports the view that through tropism SARS-CoV-2 has evolved a highly efficient membrane entry process that can act in concert with a high binding affinity of this virus and its variants for its ACE2 which in turn promotes enhanced movement of the virus from airway to epithelium. In this way ongoing mutations yielding higher affinities of SARS-CoV-2 for the ACE2 target becomes the basis for higher upper respiratory tract infectivity and greater viral spread. It is concluded that SARS-CoV-2 is constrained in the extent of its activities by the fundamental laws of physics and thermodynamics. Laws that describe diffusion and molecular binding. Moreover it can be speculated that the very earliest contact of this virus with the human mucosa defines the pathogenesis of this infection.

A hypothesis on designing strategy of effective RdRp inhibitors for the treatment of SARS-CoV-2

Vaccines are used as one of the major weapons for the eradication of pandemic. However, the rise of different variants of the SARS-CoV-2 virus is creating doubts regarding the end of the pandemic. Hence, there is an urgent need to develop more drug candidates which can be useful for the treatment of COVID-19. In the present research for the scientific hypothesis, emphasis was given on the direct antiviral therapy available for the treatment of COVID-19. In lieu of this, the available molecular targets which include Severe Acute Respiratory Syndrome Chymotrypsin-like Protease (SARS-3CLpro), Papain-Like Cysteine Protease (PLpro), and RNA-Dependent RNA Polymerase (RdRp) were explored. As per the current scientific reports and literature, among all the available molecular targets, RNA-Dependent RNA Polymerase (RdRp) was found to be a crucial molecular target for the treatment of COVID-19. Most of the inhibitors which are reported against this target consisted of the free amine group and carbonyl group which might be playing an important role in the binding interaction with the RdRp protein. Among all the reported RdRp inhibitors, remdesivir, favipiravir, and molnupiravir were found to be the most promising drugs against COVID-19. Overall, the structural features of this RNA-Dependent RNA Polymerase (RdRp) inhibitors proved the importance of pyrrolo-triazine and pyrimidine scaffolds. Previous computational models of these drug molecules indicated that substitution with the polar functional group, hydrogen bond donor, and electronegative atoms on these scaffolds may increase the activity against the RdRp protein. Hence, in line with the proposed hypothesis, in the present research work for the evaluation of the hypothesis, new molecules were designed from the pyrrolo-triazine and pyrimidine scaffolds. Further, molecular docking and MD simulation studies were performed with these designed molecules. All these designed molecules (DM-1, DM-2, and DM-3) showed the results as per the proposed hypothesis. Among all the designed molecules, DM-1 showed promising results against the RdRp protein of SARS-CoV-2. In the future, these structural features can be used for the development of new RdRp inhibitors with improved activity. Also, in the future lead compound DM-1 can be explored against the RdRp protein for the treatment of COVID-19.

Mutations in SARS-CoV-2 structural proteins: a global analysis

BACKGROUND

Emergence of new variants mainly variants of concerns (VOC) is caused by mutations in main structural proteins of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Therefore, we aimed to investigate the mutations among structural proteins of SARS-CoV-2 globally.

METHODS

We analyzed samples of amino-acid sequences (AASs) for envelope (E), membrane (M), nucleocapsid (N), and spike (S) proteins from the declaration of the coronavirus 2019 (COVID-19) as pandemic to January 2022. The presence and location of mutations were then investigated by aligning the sequences to the reference sequence and categorizing them based on frequency and continent. Finally, the related human genes with the viral structural genes were discovered, and their interactions were reported.

RESULTS

The results indicated that the most relative mutations among the E, M, N, and S AASs occurred in the regions of 7 to 14, 66 to 88, 164 to 205, and 508 to 635 AAs, respectively. The most frequent mutations in E, M, N, and S proteins were T9I, I82T, R203M/R203K, and D614G. D614G was the most frequent mutation in all six geographical areas. Following D614G, L18F, A222V, E484K, and N501Y, respectively, were ranked as the most frequent mutations in S protein globally. Besides, A-kinase Anchoring Protein 8 Like (AKAP8L) was shown as the linkage unit between M, E, and E cluster genes.

CONCLUSION

Screening the structural protein mutations can help scientists introduce better drug and vaccine development strategies.

Human genes with relative synonymous codon usage analogous to that of polyomaviruses are involved in the mechanism of polyomavirus nephropathy

Human polyomaviruses (HPyVs) can cause serious and deleterious infections in human. Yet, the molecular mechanism underlying these infections, particularly in polyomavirus nephropathy (PVAN), is not well-defined. In the present study, we aimed to identify human genes with codon usage bias (CUB) similar to that of HPyV genes and explore their potential involvement in the pathogenesis of PVAN. The relative synonymous codon usage (RSCU) values of genes of HPyVs and those of human genes were computed and used for Pearson correlation analysis. The involvement of the identified correlation genes in PVAN was analyzed by validating their differential expression in publicly available transcriptomics data. Functional enrichment was performed to uncover the role of sets of genes. The RSCU analysis indicated that the A- and T-ending codons are preferentially used in HPyV genes. In total, 5400 human genes were correlated to the HPyV genes. The protein-protein interaction (PPI) network indicated strong interactions between these proteins. Gene expression analysis indicated that 229 of these genes were consistently and differentially expressed between normal kidney tissues and kidney tissues from PVAN patients. Functional enrichment analysis indicated that these genes were involved in biological processes related to transcription and in pathways related to protein ubiquitination pathway, apoptosis, cellular response to stress, inflammation and immune system. The identified genes may serve as diagnostic biomarkers and potential therapeutic targets for HPyV associated diseases, especially PVAN.

The Ramp Atlas: facilitating tissue and cell-specific ramp sequence analyses through an intuitive web interface

Ramp sequences occur when the average translational efficiency of codons near the 5′ end of highly expressed genes is significantly lower than the rest of the gene sequence, which counterintuitively increases translational efficiency by decreasing downstream ribosomal collisions. Here, we show that the relative codon adaptiveness within different tissues changes the existence of a ramp sequence without altering the underlying genetic code. We present the first comprehensive analysis of tissue and cell type-specific ramp sequences and report 3108 genes with ramp sequences that change between tissues and cell types, which corresponds with increased gene expression within those tissues and cells. The Ramp Atlas (https://ramps.byu.edu/) allows researchers to query precomputed ramp sequences in 18 388 genes across 62 tissues and 66 cell types and calculate tissue-specific ramp sequences from user-uploaded FASTA files through an intuitive web interface. We used The Ramp Atlas to identify seven SARS-CoV-2 genes and seven human SARS-CoV-2 entry factor genes with tissue-specific ramp sequences that may help explain viral proliferation within those tissues. We anticipate that The Ramp Atlas will facilitate personalized and creative tissue-specific ramp sequence analyses for both human and viral genes that will increase our ability to utilize this often-overlooked regulatory region.

Human genes with codon usage bias similar to that of the nonstructural protein 1 gene of influenza A viruses are conjointly involved in the infectious pathogenesis of influenza A viruses

Molecular mechanisms of the non-structural protein 1 (NS1) in influenza A-induced pathological changes remain ambiguous. This study explored the pathogenesis of human infection by influenza A viruses (IAVs) through identifying human genes with codon usage bias (CUB) similar to NS1 gene of these viruses based on the relative synonymous codon usage (RSCU). CUB of the IAV subtypes H1N1, H3N2, H3N8, H5N1, H5N2, H5N8, H7N9 and H9N2 was analyzed and the correlation of RSCU values of NS1 sequences with those of the human genes was calculated. The CUB of NS1 was uneven and codons ending with A/U were preferred. The ENC-GC3 and neutrality plots suggested natural selection as the main determinant for CUB. The RCDI, CAI and SiD values showed that the viruses had a high degree of adaptability to human. A total of 2155 human genes showed significant RSCU-based correlation (p < 0.05 and r > 0.5) with NS1 coding sequences and was considered as human genes with CUB similar to NS1 gene of IAV subtypes. Differences and similarities in the subtype-specific human protein–protein interaction (PPI) networks and their functions were recorded among IAVs subtypes, indicating that NS1 of each IAV subtype has a specific pathogenic mechanism. Processes and pathways involved in influenza, transcription, immune response and cell cycle were enriched in human gene sets retrieved based on the CUB of NS1 gene of IAV subtypes. The present work may advance our understanding on the mechanism of NS1 in human infections of IAV subtypes and shed light on the therapeutic options.

Cardiovascular Dysfunction in COVID-19: Association Between Endothelial Cell Injury and Lactate

Coronavirus disease 2019 (COVID-19), an infectious respiratory disease propagated by a new virus known as Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), has resulted in global healthcare crises. Emerging evidence from patients with COVID-19 suggests that endothelial cell damage plays a central role in COVID-19 pathogenesis and could be a major contributor to the severity and mortality of COVID-19. Like other infectious diseases, the pathogenesis of COVID-19 is closely associated with metabolic processes. Lactate, a potential biomarker in COVID-19, has recently been shown to mediate endothelial barrier dysfunction. In this review, we provide an overview of cardiovascular injuries and metabolic alterations caused by SARS-CoV-2 infection. We also propose that lactate plays a potential role in COVID-19-driven endothelial cell injury.

COVID-19 pandemic: the delta variant, T-cell responses, and the efficacy of developing vaccines

Background

The mayhem COVID-19 that was ushered by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) was declared pandemic by the World Health Organization in March 2020. Since its initial outbreak in late 2019, the virus has affected hundreds of million adults in the world and killing millions in the process. After the approval of newly developed vaccines, severe challenges remain to manufacture and administer them to the adult population globally in quick time. However, we have witnessed several mutations of the virus leading to ‘waves’ of viral spread and mortality. WHO has categorized these mutations as variants of concern (VOCs) and variants of interest (VOIs). The mortality due to COVID-19 has also been associated with various comorbidities and improper immune response. This has created further complications in understanding the nature of the SARS-CoV2–host interaction that has fuelled doubts in the efficacy of the approved vaccines. Whether there is requirement of booster dose and whether the impending wave could affect the children are some of the hotly debated topics.

Materials and Methods

A systematic literature review of PubMed, Medline, Scopus, Google Scholar was utilized to understand the nature of Delta variant and how it alters our T-cell responses and cytokine production and neutralizes vaccine-generated antibodies.

Conclusion

In this review, we discuss the variants of SARS-CoV2 with specific focus on the Delta variant. We also specifically review the T-cell response against the virus and bring a narrative of various factors that may hold the key to fight against this marauding virus.

Transmission cluster of COVID-19 cases from Uruguay: emergence and spreading of a novel SARS-CoV-2 ORF6 deletion

BACKGROUND

Evolutionary changes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) include indels in non-structural, structural, and accessory open reading frames (ORFs) or genes.

OBJECTIVES

We track indels in accessory ORFs to infer evolutionary gene patterns and epidemiological links between outbreaks.

METHODS

Genomes from Coronavirus disease 2019 (COVID-19) case-patients were Illumina sequenced using ARTIC_V3. The assembled genomes were analysed to detect substitutions and indels.

FINDINGS

We reported the emergence and spread of a unique 4-nucleotide deletion in the accessory ORF6, an interesting gene with immune modulation activity. The deletion in ORF6 removes one repeat unit of a two 4-nucleotide repeat, which shows that directly repeated sequences in the SARS-CoV-2 genome are associated with indels, even outside the context of extended repeat regions. The 4-nucleotide deletion produces a frameshifting change that results in a protein with two inserted amino acids, increasing the coding information of this accessory ORF. Epidemiological and genomic data indicate that the deletion variant has a single common ancestor and was initially detected in a health care outbreak and later in other COVID-19 cases, establishing a transmission cluster in the Uruguayan population.

MAIN CONCLUSIONS

Our findings provide evidence for the origin and spread of deletion variants and emphasise indels’ importance in epidemiological studies, including differentiating consecutive outbreaks occurring in the same health facility.