Viral Spike Research Articles

COVID-19 Pathology Sheds Further Light on Balance between Neutrophil Proteases and Their Inhibitors

Excessive neutrophil influx and activation in lungs during infections, such as manifest during the ongoing SARS CoV-2 pandemic, have brought neutrophil extracellular traps (NETs) and the concomitant release of granule contents that damage surrounding tissues into sharp focus. Neutrophil proteases, which are known to participate in NET release, also enable the binding of the viral spike protein to cellular receptors and assist in the spread of infection. Blood and tissue fluids normally also contain liver-derived protease inhibitors that balance the activity of proteases. Interestingly, neutrophils themselves also express the protease inhibitor alpha-1-antitrypsin (AAT), the product of the SERPINA-1 gene, and store it in neutrophil cytoplasmic granules. The absence of AAT or mutations in the SERPINA-1 gene promotes lung remodeling and fibrosis in diseases such as chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome (ARDS) and increases the risk of allergic responses. Recent observations point to the fact that reduced activity of AAT presents a major susceptibility factor for severe COVID-19. Here, we focus attention on the mechanism of neutrophil elastase (NE) in NET release and its inhibition by AAT as an additional factor that may determine the severity of COVID-19.

Bystander effect of SARS-CoV-2 spike protein on human monocytic THP-1 cell activation and initiation of prothrombogenic stimulus representing severe COVID-19

BackgroundHypercoagulable state and thromboembolic complications are potential life-threatening events in COVID-19 patients. Our previous studies demonstrated that SARS-CoV-2 infection as well as viral spike protein expressed epithelial cells exhibit senescence with the release of inflammatory molecules, including alarmins.FindingsWe observed extracellular alarmins present in the culture media of SARS-CoV-2 spike expressing cells activate human THP-1 monocytes to secrete pro-inflammatory cytokines to a significant level. The release of THP-1 derived pro-inflammatory cytokine signature correlated with the serum of acute COVID-19 patient, but not in post-COVID-19 state. Our study suggested that the alarmins secreted by spike expressing cells, initiated phagocytosis property of THP-1 cells. The phagocytic monocytes secreted complement component C5a and generated an autocrine signal via C5aR1 receptor. The C5a-C5aR1 signal induced formation of monocyte mediated extracellular trap resulted in the generation of a prothrombogenic stimulus with activating platelets and increased tissue factor activity. We also observed an enhanced C5a level, platelet activating factor, and high tissue factor activity in the serum of acute COVID-19 patients, but not in recovered patients.ConclusionOur present study demonstrated that SARS-CoV-2 spike protein modulates monocyte responses in a paracrine manner for prothrombogenic stimulus by the generation of C5a complement component.

Comparative Assessment of the Binding and Neutralisation Activity of Bispecific Antibodies Against SARS-CoV-2 Variants.

Neutralising antibodies against SARS-CoV-2 are a vital component in the fight against COVID-19 pandemic, having the potential of both therapeutic and prophylactic applications. Bispecific antibodies (BsAbs) against SARS-CoV-2 are particularly promising, given their ability to bind simultaneously to two distinct sites of the receptor-binding domain (RBD) of the viral spike protein. Such antibodies are complex molecules associated with multi-faceted mechanisms of action that require appropriate bioassays to ensure product quality and manufacturing consistency. We developed procedures for biolayer interferometry (BLI) and a cell-based virus neutralisation assay, the focus reduction neutralisation test (FRNT). Using both assays, we tested a panel of five BsAbs against different spike variants (Ancestral, Delta and Omicron) to evaluate the use of these analytical methods in assessing binding and neutralisation activities of anti-SARS-CoV-2 therapeutics. We found comparable trends between BLI-derived binding affinity and FRNT-based virus neutralisation activity. Antibodies that displayed high binding affinity against a variant were often followed by potent neutralisation at lower concentrations, whereas those with low binding affinity also demonstrated reduced neutralisation activity. The results support the utility of BLI and FRNT assays in measuring variant-specific binding and virus neutralisation activity of anti-SARS-CoV-2 antibodies.

Emerging Dominant SARS-CoV-2 Variants.

Accurate and reliable forecasting of emerging dominant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants enables policymakers and vaccine makers to get prepared for future waves of infections. The last three waves of SARS-CoV-2 infections caused by dominant variants, Omicron (BA.1), BA.2, and BA.4/BA.5, were accurately foretold by our artificial intelligence (AI) models built with biophysics, genotyping of viral genomes, experimental data, algebraic topology, and deep learning. On the basis of newly available experimental data, we analyzed the impacts of all possible viral spike (S) protein receptor-binding domain (RBD) mutations on the SARS-CoV-2 infectivity. Our analysis sheds light on viral evolutionary mechanisms, i.e., natural selection through infectivity strengthening and antibody resistance. We forecast that BP.1, BL*, BA.2.75*, BQ.1*, and particularly BN.1* have a high potential to become the new dominant variants to drive the next surge. Our key projection about these variants dominance made on Oct. 18, 2022 (see arXiv:2210.09485) became reality in late November 2022.

Variations within the Glycan Shield of SARS-CoV-2 Impact Viral Spike Dynamics

The emergence of SARS-CoV-2 variants alters the efficacy of existing immunity, whether arisen naturally or through vaccination. Understanding the structure of the viral spike assists in determining the impact of mutations on the antigenic surface. One class of mutation impacts glycosylation attachment sites, which have the capacity to influence the antigenic structure beyond the immediate site of attachment. Here, we compare the site-specific glycosylation of recombinant viral spike mimetics of B.1.351 (Beta), P.1 (Gamma), B.1.617.2 (Delta), B.1.1.529 (Omicron). The P.1 strain exhibits two additional N-linked glycan sites compared to the other variants analyzed and we investigate the impact of these glycans by molecular dynamics. The acquired N188 site is shown to exhibit very limited glycan maturation, consistent with limited enzyme accessibility. Structural modeling and molecular dynamics reveal that N188 is located within a cavity by the receptor binding domain, which influences the dynamics of these attachment domains. These observations suggest a mechanism whereby mutations affecting viral glycosylation sites have a structural impact across the protein surface.

A Lentiviral Pseudotype System to Characterize SARS-CoV-2 Glycoprotein.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2 causes worldwide COVID-19 pandemic and poses agreat threat to global public health. Due to its high pathogenicity and infectivity, live SARS-CoV-2 is classified as a BSL-3 agent and has to be handled in BSL-3 condition. Nevertheless, entry of SARS-CoV-2 is mediated by viral spike (S) glycoprotein, and pseudovirus with SARS-CoV-2S protein can mimic every entry step of SARS-CoV-2 virus and be studied in BSL-2 settings. In this chapter, we describe a detailed protocol of production of lentivirus-based SARS-CoV-2S pseudovirus and its application in study of virus entry and determination of neutralizing antibody titer of human sera against SARS-CoV-2.

Characterization of SARS-CoV-2 Glycoprotein Using a Quantitative Cell-Cell Fusion System.

Coronaviruses (CoVs) infect host cells throughthe fusion of viral and cellular membrane and may also spread to the neighboring uninfected cells from infected cells through cell-cell fusion. The viral spike (S) glycoproteins play an essential role in mediating membrane fusion. Here, we present a luciferase-based quantitative assay to measurethe efficiency of cell-cell fusion mediated by theS protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This method applies to S proteins of theother coronaviruses and can be adapted to fusion proteins of other enveloped viruses.

Higher Infection Risk among Health Care Workers and Lower Risk among Smokers Persistent across SARS-CoV-2 Waves-Longitudinal Results from the Population-Based TiKoCo Seroprevalence Study.

SARS-CoV-2 seroprevalence was reported as substantially increased in medical personnel and decreased in smokers after the first wave in spring 2020, including in our population-based Tirschenreuth Study (TiKoCo). However, it is unclear whether these associations were limited to the early pandemic and whether the decrease in smokers was due to reduced infection or antibody response. We evaluated the association of occupation and smoking with period-specific seropositivity: for the first wave until July 2020 (baseline, BL), the low infection period in summer (follow-up 1, FU1, November 2020), and the second/third wave (FU2, April 2021). We measured binding antibodies directed to SARS-CoV-2 nucleoprotein (N), viral spike protein (S), and neutralizing antibodies at BL, FU1, and FU2. Previous infection, vaccination, smoking, and occupation were assessed by questionnaires. The 4181 participants (3513/3374 at FU1/FU2) included 6.5% medical personnel and 20.4% current smokers. At all three timepoints, new seropositivity was higher in medical personnel with ORs = 1.99 (95%-CI = 1.36-2.93), 1.41 (0.29-6.80), and 3.17 (1.92-5.24) at BL, FU1, and FU2, respectively, and nearly halved among current smokers with ORs = 0.47 (95%-CI = 0.33-0.66), 0.40 (0.09-1.81), and 0.56 (0.33-0.94). Current smokers compared to never-smokers had similar antibody levels after infection or vaccination and reduced odds of a positive SARS-CoV-2 result among tested. Our data suggest that decreased seroprevalence among smokers results from fewer infections rather than reduced antibody response. The persistently higher infection risk of medical staff across infection waves, despite improved means of protection over time, underscores the burden for health care personnel.

THE RELATION OF ACE2 AND TMPRSS2 NASOPHARYNGEAL EXPRESSION WITH DISEASE SEVERITY IN VIETNAMESE COVID-19 PATIENTS

Introduction: ACE2 and TMPRSS2 are two crucial proteins of host cell membrane helping SARSCoV-2 viral infection to cause COVID-19 disease. ACE2 is a receptor for binding of the viral spike (S) protein and TMPRSS2 following cleaves the S protein at the S1/S2 and S'2 sites for membrane fusion.Aim: This study aimed to evaluate the expression of nasopharyngeal ACE2 and TMPRSS2 upon admission in relationship with the subsequent clinical course during hospitalization of COVID-19 patients.Material and methods: Representative 29 and 23 nasopharyngeal fluid samples collected upon admission from typical severe and mild COVID-19 patients hospitalized in the National Hospital for Tropical Diseases (Vietnam), respectively, were relatively compared RNA expression of ACE2 and TMPRSS2 by using Realtime-PCR with specific primers. SARS-CoV-2 cases were diagnosed clinically,blood and biochemical parameter, X-ray/CT and confirmed by RT-PCR.Results: The RNA expression of TMPRSS2 was relative higher (1.36 fold) in severe group in comparison with mild patients (p = 0.0004), but the level of ACE2 expression was no difference between two groups.Conclusion: TMPRSS2 but not ACE2 gene expression in the nasopharyngeal mucosa may promote the severity of COVID-19 patients but requires further study in larger samples.

1135. Monoclonal Antibody Therapeutics in US Veterans against Delta and Omicron SARS-CoV-2 Variants

Abstract Background Anti-SARS-CoV-2 monoclonal antibodies (mABs) target the viral spike protein and have been shown to have clinical benefit in treating COVID-19. The FDA had given emergency use authorization to mAB products: bamlanivimab+etesevinab (BAM), casirivimab+imdevimab (CAS), sotrovimab (SOT). However, due to reduced activity against the omicron variant the FDA recommended against use of BAM and CAS. SOT has retained efficacy against omicron. We reviewed the utilization of mABS in our institution during the pandemic as delta variant was replaced by omicron. Methods Retrospective chart review of US Veterans (USV) with confirmed SARS-CoV-2 infection who received mABs from 9/1/2021 to 2/28/22 at Northport Veterans Affairs Medical Center. Demographic data, comorbidities, choice of mAB, history of COVID-19 vaccination, SARS-CoV-2 sequencing, and IgG levels to the receptor-biding domain (RBD) of the spike protein in vaccinated USV were reviewed. Results 66 USV received mAB therapy, tolerated well. 30 got CAS, 29 BAM, 7 SOT. 52 doses were given from Dec 2021 to Jan 2022, none were given in Feb. The median age of the cohort was 72.5 (range 32 to 97 years). 97% were men. 85% White, 12% Black, 3% Hispanic. 22 USV were not vaccinated. The vaccine recipients were: 3 Janssen, Moderna-2 shots (MOD-2): 6; MOD-3: 3; Pfizer 2 (PFZ-2) shots: 22; PFZ-3:10 The median days of COVID diagnosis from last dose of vaccine: Janssen 211 days (104 to 257); MOD-2 291 (205-322); MOD-3 56 (16-61), PFZ-2 222 (96-302) PFZ-3 78 (8-112). 62% had cough, dyspnea 24%, malaise 50%, diarrhea 11%, anosmia 11%, sore throat 17%, nasal congestion 41%, fever 32% Median BMI 30.8 (16.6 - 47.3). 36% had Diabetes, HTN 67%. COPD 23%, Asthma 11%, CAD 32%, HLD 67%; one woman was 28 weeks pregnant. Two coinfections with rhinovirus, 1 with RSV. 20 vaccine recipients had anti-SARS-CoV-2 RBD titers at presentation, median 2.60 (0.06-48.08). 11 USV were hospitalized but only 4 got steroids/remdesivir. 3 USV died but not directly due to COVID. 15 USV with omicron who received CAS (8) and BAM (7) survived. See tables for further data. Demographic Data of US Veterans after receiving monoclonal antibody therapy Data on hospitalized US Veterans after receiving monoclonal antibody therapy Conclusion As the pandemic transitioned from Delta to Omicron variants, mAB treatments in USV remained successful even in those USV who received therapies not active for omicron. Delta and omicron infections were seen in vaccinated and boosted USV. Disclosures All Authors: No reported disclosures.

Quantifying Antibody Persistence After a Single Dose of COVID-19 Vaccine Ad26.COV2.S in Humans Using a Mechanistic Modeling and Simulation Approach.

Understanding persistence of humoral immune responses elicited by vaccination against coronavirus disease 2019 (COVID-19) is critical for informing the duration of protection and appropriate booster timing. We developed a mechanistic model to characterize the time course of humoral immune responses in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-seronegative adults after primary vaccination with the Janssen COVID-19 vaccine, Ad26.COV2.S. The persistence of antibody responses was quantified through mechanistic modeling-based simulations. Two biomarkers of humoral immune responses were examined: SARS-CoV-2 neutralizing antibodies determined by wild-type virus neutralization assay (wtVNA) and spike protein-binding antibodies determined by indirect spike protein enzyme-linked immunosorbent assay (S-ELISA). The persistence of antibody responses was defined as the period of time during which wtVNA and S-ELISA titers remained above the lower limit of quantification. A total of 442 wtVNA and 1,185 S-ELISA titers from 82 and 220 participants, respectively, were analyzed following administration of a single dose of Ad26.COV2.S (5 × 1010 viral particles). The mechanistic model adequately described the time course of observed wtVNA and S-ELISA serum titers and its associated variability up to 8 months following vaccination. Mechanistic model-based simulations show that single-dose Ad26.COV2.S elicits durable but waning antibody responses up to 24 months following immunization. Of the estimated model parameters, the production rate of memory B cells was decreased in older adults relative to younger adults, and the antibody production rate mediated by long-lived plasma cells was increased in women relative to men. A steeper waning of antibody responses was predicted in men and in older adults.

Single-virus tracking reveals variant SARS-CoV-2 spike proteins induce ACE2-independent membrane interactions.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a global health crisis after its emergence in 2019. Replication of the virus is initiated by binding of the viral spike (S) protein to human angiotensin-converting enzyme 2 (ACE2) on the target cell surface. Mutations acquired by SARS-CoV-2 S variants likely influence virus-target cell interaction. Here, using single-virus tracking to capture these initial steps, we observe how viruses carrying variant S interact with target cells. Specificity for ACE2 occurs for viruses with the reference sequence or D614G mutation. Analysis of the Alpha, Beta, and Delta SARS-CoV-2 variant S proteins revealed a progressive altered cell interaction with a reduced dependence on ACE2. Notably, the Delta variant S affinity was independent of ACE2. These enhanced interactions may account for the increased transmissibility of variants. Knowledge of how mutations influence cell interaction is essential for vaccine development against emerging variants of SARS-CoV-2.

Reduced immunogenicity of BNT162b2 booster vaccination in combination with a tetravalent influenza vaccination: results of a prospective cohort study in 838 health workers

ObjectiveTo investigate the immunogenicity and safety of BNT162b2 booster vaccination with and without a tetravalent influenza vaccine. MethodsA prospective, open-label cohort study on immunogenicity and safety of COVID-19 booster vaccination with or without a tetravalent influenza vaccine was performed. Eight hundred thirty-eight health care workers were included in the following study arms: BNT162b2 booster-only, influenza-vaccine-only or combination of both. Levels of antibodies against SARS-CoV-2 spike receptor binding domain, and haemagglutinin inhibition tested for four different influenza strains (A(H1N1)pdm09, A(H3N2), B/Victoria, B/Yamagata) were measured at the time of vaccination and 4 weeks later. ResultsAfter 4 weeks, median (interquartile range) levels of antibodies against the receptor binding domain of the viral spike (S) protein and relative change from baseline were high in individuals who received BNTb162b2 booster vaccination only (absolute: 16 600 [10 980–24 360] vs. 12 630 [8198–18 750] BAU/mL [p < 0.0001]; relative increase: 49% [23.6–95.3] vs. 40% [21.9–80.6] [p 0.048]; booster-only n = 521 vs. combination-arm n = 229 respectively). Results were confirmed after matching for sex, age, body mass index, baseline antibody levels and vaccine compound received for primary immunization (absolute: 13 930 [10 610–22 760] vs. 12 520 [8710–17 940]; [p 0.031]; relative increase: 55.7% [27.8–98.5] vs. 42.2% [22.9–74.5]; p 0.045). Adverse events were almost identical in the booster-only and the combination-arm, but numerically low in the influenza arm (525/536 [97.9%] vs. 235/240 [97.9%] vs. 26/33 [78.8 %]). DiscussionAlthough no safety concerns occurred, our study provides evidence on reduced immunogenicity of a BNT162b2 booster vaccination in combination with a tetravalent influenza vaccine. Further studies investigating new influenza variants as well as potential differences vaccine effectiveness are needed.

SARS-CoV-2 Spike Protein Induces Hemagglutination: Implications for COVID-19 Morbidities and Therapeutics and for Vaccine Adverse Effects

Experimental findings for SARS-CoV-2 related to the glycan biochemistry of coronaviruses indicate that attachments from spike protein to glycoconjugates on the surfaces of red blood cells (RBCs), other blood cells and endothelial cells are key to the infectivity and morbidity of COVID-19. To provide further insight into these glycan attachments and their potential clinical relevance, the classic hemagglutination (HA) assay was applied using spike protein from the Wuhan, Alpha, Delta and Omicron B.1.1.529 lineages of SARS-CoV-2 mixed with human RBCs. The electrostatic potential of the central region of spike protein from these four lineages was studied through molecular modeling simulations. Inhibition of spike protein-induced HA was tested using the macrocyclic lactone ivermectin (IVM), which is indicated to bind strongly to SARS-CoV-2 spike protein glycan sites. The results of these experiments were, first, that spike protein from these four lineages of SARS-CoV-2 induced HA. Omicron induced HA at a significantly lower threshold concentration of spike protein than the three prior lineages and was much more electropositive on its central spike protein region. IVM blocked HA when added to RBCs prior to spike protein and reversed HA when added afterward. These results validate and extend prior findings on the role of glycan bindings of viral spike protein in COVID-19. They furthermore suggest therapeutic options using competitive glycan-binding agents such as IVM and may help elucidate rare serious adverse effects (AEs) associated with COVID-19 mRNA vaccines, which use spike protein as the generated antigen.

Exploring Highly Conserved Regions of SARS-CoV-2 Spike S2 Subunit as Targets for Fusion Inhibition Using Chimeric Proteins.

Since the beginning of the COVID-19 pandemic, considerable efforts have been made to develop protective vaccines against SARS-CoV-2 infection. However, immunity tends to decline within a few months, and new virus variants are emerging with increased transmissibility and capacity to evade natural or vaccine-acquired immunity. Therefore, new robust strategies are needed to combat SARS-CoV-2 infection. The viral spike composed of S1 and S2 subunits mediates viral attachment and membrane fusion to infect the host cell. In this process, interaction between the highly conserved heptad repeat 1 and 2 regions (HR1 and HR2) of S2 is crucial and for this reason; these regions are promising targets to fight SARS-CoV-2. Here, we describe the design and characterization of chimeric proteins that structurally imitate the S2 HR1 region in a trimeric coiled-coil conformation. We biophysically characterized the proteins and determined their capacity to bind the HR2 region, as well as their inhibitory activity of SARS-CoV-2 infection in vitro. HR1 mimetic proteins showed conformational heterogeneity and a propensity to form oligomers. Moreover, their structure is composed of subdomains with varied stability. Interestingly, the full HR1 proteins showed high affinity for HR2-derived peptides and SARS-CoV-2 inhibitory activity, whereas smaller proteins mimicking HR1 subdomains had a decreased affinity for their complementary HR2 region and did not inhibit the virus. The results provide insight into effective strategies to create mimetic proteins with broad inhibitory activity and therapeutic potential against SARS-CoV-2.

SARS-CoV-2 spike protein variant binding affinity to an angiotensin-converting enzyme 2 fusion glycoproteins.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of the Coronavirus disease 2019 (Covid-19) pandemic, continues to evolve and circulate globally. Current prophylactic and therapeutic countermeasures against Covid-19 infection include vaccines, small molecule drugs, and neutralizing monoclonal antibodies. SARS-CoV-2 infection is mainly mediated by the viral spike glycoprotein binding to angiotensin converting enzyme 2 (ACE2) on host cells for viral entry. As emerging mutations in the spike protein evade efficacy of spike-targeted countermeasures, a potential strategy to counter SARS-CoV-2 infection is to competitively block the spike protein from binding to the host ACE2 using a soluble recombinant fusion protein that contains a human ACE2 and an IgG1-Fc domain (ACE2-Fc). Here, we have established Chinese Hamster Ovary (CHO) cell lines that stably express ACE2-Fc proteins in which the ACE2 domain either has or has no catalytic activity. The fusion proteins were produced and purified to partially characterize physicochemical properties and spike protein binding. Our results demonstrate the ACE2-Fc fusion proteins are heavily N-glycosylated, sensitive to thermal stress, and actively bind to five spike protein variants (parental, alpha, beta, delta, and omicron) with different affinity. Our data demonstrates a proof-of-concept production strategy for ACE2-Fc fusion glycoproteins that can bind to different spike protein variants to support the manufacture of potential alternative countermeasures for emerging SARS-CoV-2 variants.

Potential antiviral peptides targeting the SARS-CoV-2 spike protein

BackgroundThe coronavirus disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection became an international pandemic and created a public health crisis. The binding of the viral Spike glycoprotein to the human cell receptor angiotensin-converting enzyme 2 (ACE2) initiates viral infection. The development of efficient treatments to combat coronavirus disease is considered essential.MethodsAn in silico approach was employed to design amino acid peptide inhibitor against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. The designed inhibitor (SARS-CoV-2 PEP 49) consists of amino acids with the α1 helix and the β4 - β5 sheets of ACE2. The PEP-FOLD3 web tool was used to create the 3D structures of the peptide amino acids. Analyzing the interaction between ACE2 and the RBD of the Spike protein for three protein data bank entries (6M0J, 7C8D, and 7A95) indicated that the interacting amino acids were contained inside two regions of ACE2: the α1 helical protease domain (PD) and the β4 - β5 sheets.ResultsMolecular docking analysis of the designed inhibitor demonstrated that SARS-CoV-2 PEP 49 attaches directly to the ACE2 binding site of the Spike protein with a binding affinity greater than the ACE2, implying that the SARS-CoV-2 PEP 49 model may be useful as a potential RBD binding blocker.

A Monoclonal Antibody Targeting C-Terminal Domain of Transmissible Gastroenteritis Virus Spike Protein.

The structure and function of the C-terminus domain (CTD) of porcine transmissible gastroenteritis virus (TGEV) spike protein remain largely unknown, thereby a specific monoclonal antibody (MAb) allows us to fully understand this domain. In this study, we developed a murine MAb against CTD of TGEV spike protein, as evidenced by the results of indirect fluorescent assay, Western blotting, and fluorescence-activated cell sorter. Further study showed that the MAb is able to exclusively recognize a 12-residue peptide (FKNVSDGVIYSV) derived from CTD of TGEV spike protein. This MAb can be used to elucidate the potential function of CTD of TGEV spike in virus attachment and entry, and warrants further intensive investigation.

Evidence for Interplay Between the Renin-Angiotensin System and Toll-Like Receptor 4 Signaling Pathways in the Induction of Virus-Induced Acute Lung Injury.

Dedication: This article is dedicated to Howard Young, an exceptional scientist who has provided outstanding mentorship to many postbaccalaureates, graduate students, and postdoctoral fellows during his career. Howard has been a colleague to many and was never tired of learning new things. He has brought "thinking out of the box" to the level of an art form and has always provided thoughtful and constructive suggestions to those who have sought his counsel. I am personally greatly indebted to Howard for his guidance in molecular biology over the past 30 years, and hope that we will continue to share a passion for learning and mentoring others for years to come. Thank you, Howard! -Stephanie N. Vogel The SARS-CoV-2 pandemic has led to an unprecedented explosion in studies that have sought to identify key mechanisms that underlie the ravaging aspects of this disease on individuals. SARS-CoV-2 virus gains access to cells by (1) binding of the viral spike (S) protein to cell-associated angiotensin-converting enzyme 2 (ACE2), a key receptor in the renin-angiotensin system (RAS), followed by (2) cleavage of S protein by a cellular serine protease ("S protein priming") to facilitate viral entry. Dysregulation of the RAS system has been implicated in the spectrum of clinical symptoms associated with SARS-CoV-2, including hypercytokinemia, elevated markers of endothelial injury and thrombosis, and both localized and systemic inflammation. However, the underlying mechanisms have yet to be fully delineated.

Acute pericarditis following mRNA COVID-19 vaccination: An unforeseen event

<h2>Background</h2> In this article, we reported a case of mRNA COVID-19 vaccination-induced pericarditis. A healthy 32-year-old gentleman who had no medical illness presented with left-sided pleuritic chest pain with a pain score of 8/10, a few days after 2nd dose of mRNA COVID-19 vaccination. The symptom was associated with palpitation, radiating to the axilla, and improved with leaning forward. Despite normal cardiac enzymes, serial electrocardiograms were suggestive of pericarditis and echocardiogram showed features of pericardial thickening. Infective markers and autoimmune screening sent were not significant. The patient was treated with high-dose NSAIDs and colchicine and recovered well. A repeated echocardiogram after 1 week of treatment completion showed resolved pericardial thickening and normal findings. <h3>Discussion</h3> To date, rising cases have been reported on the incidence of pericarditis post mRNA COVID-19 vaccine. This raises suspicion on why this event only occurs after vaccine with the mRNA-based platform. Several hypotheses have been postulated. It has been suspected that mRNA vaccines possibly generate a very high signal antibody response in certain individuals, thus eliciting a response similar to that of Multisystem Inflammatory Syndrome in children (MIS-C) or mimicking an autoimmune-like response which targets pericardial lining. mRNA vaccines can induce a non-specific innate inflammatory response between the viral spike protein and an unknown cardiac protein. Another hypothesized mechanism, the RNA in the vaccine itself leads to cytokine activation of pre-existing autoreactive immune cells as young people usually have higher seroprevalence of SARS-COV-2 despite being asymptomatic. <h3>Conclusion</h3> We wish to highlight the importance of monitoring and treating adverse events notable by patients. Healthcare providers should maintain high suspicion in the appropriate clinical situation. All cases were self-limited and showed satisfactory recovery during follow-up. We emphasize the benefit of vaccination outweighs the risk.