Receptor Angiotensin-converting Enzyme Research Articles

Identification of a Pentasaccharide Lead Compound with High Affinity to the SARS-CoV-2 Spike Protein via In Silico Screening.

The spike (S) protein on the surface of the SARS-CoV-2 virus is critical to mediate fusion with the host cell membrane through interaction with angiotensin-converting enzyme 2 (ACE2). Additionally, heparan sulfate (HS) on the host cell surface acts as an attachment factor to facilitate the binding of the S receptor binding domain (RBD) to the ACE2 receptor. Aiming at interfering with the HS-RBD interaction to protect against SARS-CoV-2 infection, we have established a pentasaccharide library composed of 14,112 compounds covering the possible sulfate substitutions on the three sugar units (GlcA, IdoA, and GlcN) of HS. The library was used for virtual screening against RBD domains of SARS-CoV-2. Molecular modeling was carried out to evaluate the potential antiviral properties of the top-hit pentasaccharide focusing on the interactive regions around the interface of RBD-HS-ACE2. The lead pentasaccharide with the highest affinity for RBD was analyzed via drug-likeness calculations, showing better predicted druggable profiles than those currently reported for RBD-binding HS mimetics. The results provide significant information for the development of HS-mimetics as anti-SARS-CoV-2 agents.

Low-Entropy Hydration Shells at the Spike RBD's Binding Site May Reveal the Contagiousness of SARS-CoV-2 Variants.

The infectivity of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is primarily determined by the binding affinity between the receptor-binding domain (RBD) of the spike protein and the angiotensin-converting enzyme 2 (ACE2) receptor. Here, through screening off pseudo hydrophilic groups on protein surfaces, the distribution of low-entropy regions on hydration shells of the ACE2 receptor and the RBDs of multiple SARS-CoV-2 variants was demonstrated. Shape matching between the low-entropy hydration shells of multiple SARS-CoV-2 variants and the ACE2 receptor has been identified as a mechanism that drives hydrophobic attraction between the RBDs and the ACE2 receptor, which estimates the binding affinity. Low-entropy regions of the hydration shells, which play important roles in determining the binding of other viruses and their receptors, are demonstrated. The RBD-ACE2 binding is thus found to be guided by hydrophobic collapse between the shape-matched low-entropy regions of the hydration shells of the proteins. A measure of the low-entropy status of the hydration shells can be estimated by calculating genuine hydrophilic groups within the binding sites. An important indicator of the contagiousness of SARS-CoV-2 variants is the low-entropy level of its hydration shells at the spike protein binding site.

Antibody-mediated SARS-CoV-2 entry in cultured cells.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters host cells by first engaging its cellular receptor angiotensin converting enzyme 2 (ACE2) to induce conformational changes in the virus-encoded spike protein and fusion between the viral and target cell membranes. Here, we report that certain monoclonal neutralizing antibodies against distinct epitopic regions of the receptor-binding domain of the spike can replace ACE2 to serve as a receptor and efficiently support membrane fusion and viral infectivity in vitro. These receptor-like antibodies can function in the form of a complex of their soluble immunoglobulin G with Fc-gamma receptor I, a chimera of their antigen-binding fragment with the transmembrane domain of ACE2 or a membrane-bound B cell receptor, indicating that ACE2 and its specific interaction with the spike protein are dispensable for SARS-CoV-2 entry. These results suggest that antibody responses against SARS-CoV-2 may help expand the viral tropism to otherwise nonpermissive cell types with potential implications for viral transmission and pathogenesis.

ACE2 Receptor: A Potential Pharmacological Target in COVID-19.

Studies have shown that injection of recombinant angiotensin-converting enzyme 2 (ACE2) significantly increased circulatory levels of ACE2 activity, reduced cardiac hypertrophy and fibrosis, and effectively lowered blood pressure. In addition, recombinant ACE2 ameliorated albuminuria and might contribute to renal protection. Meanwhile, potential pharmacological treatments based on ACE2 are attracting increasing attention from scientists following a growing understanding of the role of the ACE2 receptor in the pathogenesis of coronavirus disease 2019 (COVID-19). In this article, we comprehensively summarized the literature on the structure, distribution, and function of ACE2. More importantly, we draw a conclusion that ACE2 decoys such as sACE2, hrsACE2 and ACE2-derived peptides, drugs down-regulating the ACE2 or TMPRSS2 gene expression, and the application of epigenetic modifiers and Traditional Chinese Medicine might represent promising approaches for the future of COVID-19 treatment.

ՄԻԶԱՅԻՆ ՀԱՄԱԿԱՐԳԻ ԻՆԿՐՈՒՍՏԱՑԻԱՆԵՐԸ COVID-19-ՈՎ ՀԻՎԱՆԴՆԵՐԻ ՇՐՋԱՆՈՒՄ (ՏԵՍՈՒԹՅԱՆ ՎԵՐԼՈՒԾՈՒԹՅՈՒՆ)

Since 11.03.2020 the World Health Organization has declared the coronavirus disease (COVID-19) caused by a new type of coronavirus (SARS CoV-2) as a global pandemic. Coronaviruses are single-stranded RNA viruses divided into four main classes: A, B, C, and D. SARS CoV-2 is an RNA beta-coronavirus. The most common complication of the disease is the bilateral viral pneumonia, which leads to respiratory failure in many patients. COVID-19 is multisystemic in nature and can cause damage to almost any human organ. The organs of the urinary system are no exception. SARS-CoV-2 has a specific three-dimensional protein structure characterized by a strong binding to the angiotensin-converting enzyme 2 (ACE2) receptor. Under these conditions, ACE2-producing human organs can act as target cells for SARS-CoV-2. Encrusted cystitis is a rare pathology, the main cause of which is urinary infection, especially with the urea-splitting bacteria. C. urealyticum is a gram-positive bacterium that causes alkalinization of the urine by breaking down urea to ammonia. The disease is characterized by calcification of the bladder mucosa. In our opinion, encrusted cystitis can be considered as a complication of the new coronavirus infection. Its pathogenetic basis is probably the affinity of SARS CоV-2 to ACE2 receptors in the urothelium. Thus, summarizing the results obtained from the researches carried out by various authors, we conclude that no descriptive work has been done on the course, clinical picture, treatment results, as well as the features of the pathological picture of encrusted cystitis associated with COVID-19. In this case, new studies with a larger number of patients are needed, which will enable not only to evaluate the results of individual methods, but also to perform an analysis of these results. In our opinion, encrusted cystitis can be considered as a complication of novel coronavirus infection. Taking into account the aforementioned, there is a need to work on the discussed problems.

Highly potent dual-targeting angiotensin-converting enzyme 2 (ACE2) and Neuropilin-1 (NRP1) peptides: A promising broad-spectrum therapeutic strategy against SARS-CoV-2 infection

The efficacy of approved vaccines has been diminishing due to the increasing advent of SARS-CoV-2 variants with diverse mutations that favor sneak entry. Nonetheless, these variants recognize the conservative host receptors angiotensin-converting enzyme 2 (ACE2) and neuropilin-1 (NRP1) for entry, rendering the dual blockade of ACE2 and NRP1 an advantageous pan-inhibition strategy. Here, we identified a highly potent dual-targeting peptide AP-1 using structure-based virtual screening protocol. AP-1 had nanoscale binding affinities for ACE2 (Kd = 6.1 ± 0.2 nM) and NRP1 (Kd = 13.4 ± 1.2 nM) and approximately 102- and 8-fold stronger than positive inhibitors S471–503 and NMTP-5, respectively. Further evidence in pseudovirus cell infection and cytotoxicity assays demonstrated that AP-1 exhibited remarkable entry inhibition of variants of concern (VOCs) of SARS-CoV-2 without impairing host cell viability. Together, our findings suggest that AP-1 with dual-targeting ACE2/NRP1 efficacy could be a promising broad-spectrum agent for treating SARS-CoV-2 emerging VOCs.

Molecular dynamic simulation reveals spider antimicrobial peptide Latarcin-1 and human eosinophil cationic protein as peptide inhibitors of SARS-CoV-2 variants

COVID-19 has rapidly proliferated around 180 countries, and new cases are reported frequently. No peptide medication has been developed that can reliably block SARS-CoV-2 infection. The investigation focuses on the crucial host receptors angiotensin-converting enzyme 2 (ACE2) , which can bind receptor-binding domain (RBD) on the SARS-CoV-2 spike protein (S). To investigate the inhibitory effects of human Eosinophil Cationic Protein (hECP) and Latarcin-1 (L1)on SARS-CoV-2 infection, we have selected them as research subjects. Further, we ran extensive molecular dynamics simulations to bring the docked peptide-ACE2 complex into its equilibrium state. The outcomes were then evaluated with g_MMPBSA and interaction analysis. We have also considered the Delta and Omicron variants to examine these peptides’ inhibitory effects. The experimental findings revealed an enhanced capability of L1 and hECP as SARS-CoV-2 inhibitors, occupying hot spots and numerous key residues in ACE2. These include ASP30, ASP38, GLU35 and GLU75, which significantly inhibit the binding of RBD and ACE2 and are effective against two common variants in a similar manner. In addition, this study can serve as a springboard for future research on SARS-CoV-2 inhibitors. Communicated by Ramaswamy H. Sarma

FRI329 COVID-19: An Uncommon Cause Of Hypophysitis

Abstract Disclosure: W. Medina-Torres: None. M.A. Ortiz-Rivera: None. L.N. Madera Marin: None. A. Rosado-Burgos: None. L.R. Sepulveda-Garcia: None. L. El Musa Penna: None. M. Ramirez: None. L.A. Gonzalez-Rodriguez: None. M. Alvarado: None. M. Feliciano-Emmanvel: None. COVID-19 is an infectious disease caused by the SARS-CoV-2 virus. One of the virus four structural proteins, the spike(S) protein, contains a region that binds to the extracellular domain of angiotensin-converting enzyme 2 (ACE2). The virus uses the S protein to enter the cell by binding to the ACE2 receptor. Literature has reported that ACE2 receptors are extensively expressed in numerous human tissues and organs, such as in the heart, lung, kidney, testis and brain. Despite it is demonstrated that lungs inflammation is one of the main symptoms during SARS-CoV-2 infection, the moderate expression of ACE2 among other organs may explain the involvement and subsequent impairments of various organs during and after the SARS-CoV-2 infection. Although ACE2 is expressed in several endocrine glands, including the pancreas, thyroid gland, ovaries and testes; pituitary gland expression is limited. Only few cases have been reported in the literature of direct damage to the pituitary gland post covid-19 infection. This is the case of a 31-year-old healthy athlete female without prior systemic illness who was taken to ER after developing hypotension and symptomatic hypoglycemia while flying from Barbados to Miami. Upon questioning, patient referred she was in her usual state of healthy athletic performance until 7 months ago when had mild symptomatic COVID-19. She was 4-months post-partum of a healthy baby and lactating normally, but after the 2-weeks isolation period since COVID-19 infection, she had no return of menstruation and unable to lactate. In addition, patient developed a depressive state, loss of appetite and progressive weight loss. Was found with low Blood pressure and initial laboratories showed pancytopenia and sustained hypoglycemia requiring uninterrupted D10 IV infusion. Laboratory work-up revealed both central adrenal insufficiency (ACTH <1.5 pg/mL and serum cortisol 0.20 mcg/dL), secondary hypothyroidism (TSH: 2.8 mIU/L and free T4: 0.36 ng/dL). Contrast enhanced magnetic resonance imaging (MRI) of the brain was performed with evidence of prominent partial empty sella and slight nodular thickening of the pituitary stalk. Based on these findings a presumptive diagnosis of hypophysitis was made. Rapid clinical improvement was observed on corticosteroid replacement with resolution of hypoglycemia, hypotension, and anorexia, but diabetes insipidus was unmask. Additional laboratories revealed there was definitive panhypopituitarism, with evidence of hypogonadotropic hypogonadism, hypoprolactinemia and growth hormone deficiency. This case illustrates panhypopituitarism secondary to hypophysitis as an uncommon COVID-19 virus sequel. Thus, in patients with persistent non-specific symptoms post COVID-19 infection, it is important to have a high index of suspicious for endocrinopathies such as hypophysitis in order to provide prompt therapy and improve quality of life. Presentation: Friday, June 16, 2023

Chiral distinction between hydroxychloroquine enantiomers in binding to angiotensin-converting enzyme 2, the forward receptor of SARS-CoV-2

Soon after the outset of the Coronavirus Disease 2019 (COVID-19) pandemic (March-April 2020), formulations of the old antimalarial racemic drug hydroxychloroquine (HCQ) sulfate were authorized by the U.S. Food and Drug Administration (FDA) for emergency treatment of hospitalized patients with COVID-19. A call for the chiral switch of HCQ to the single enantiomer (S)-(+)-HCQ for treating the disease followed. The above authorizations were later withdrawn. Angiotensin-converting enzyme 2 (ACE2) has been recognized to be the forward receptor of SARS-CoV-2, the virus responsible for COVID-19. The objective of the present study was to evaluate the chiral distinction in the potential preferential binding of the HCQ enantiomers to ACE2, as a basis for its future drug repurposing, using high-field solution Nuclear Magnetic Resonance (NMR) spectroscopy. Proton selective spin-lattice relaxation rates were measured for selected diagnostic nuclei; in particular, protons belonging to the quinoline ring proved to be the most affected by the presence of the protein, for both (S)-(+)-HCQ and (R)-(−)-HCQ enantiomers. An increase in mono-selective relaxation rates was observed for both enantiomers. A significant difference in the magnitude of the increase was detected for all protons investigated, up to a 5-fold and an 8-fold increase in the case of (R)-(−)-HCQ and (S)-(+)-HCQ, respectively. Furthermore, comparison between the normalized mono-selective relaxation rates of the two HCQ enantiomers in their binary mixtures with ACE2 pointed out a certain preference for the (S)-(+)-HCQ enantiomer over (R)-(−)-HCQ in the interaction with ACE2. The findings form the basis for a future application of the drug repurposing/chiral-switch combination strategy to racemic HCQ in previously reported indications for hydroxychloroquine treatment and in the search for new indications in which ACE2 receptors are involved.

Structural basis of the American mink ACE2 binding by Y453F trimeric spike glycoproteins of SARS-CoV-2.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) enters the host cell by binding to angiotensin-converting enzyme 2 (ACE2). While evolutionarily conserved, ACE2 receptors differ across various species and differential interactions with Spike (S) glycoproteins of SARS-CoV-2 viruses impact species specificity. Reverse zoonoses led to SARS-CoV-2 outbreaks on multiple American mink (Mustela vison) farms during the pandemic and gave rise to mink-associated S substitutions known for transmissibility between mink and zoonotic transmission to humans. In this study, we used bio-layer interferometry (BLI) to discern the differences in binding affinity between multiple human and mink-derived S glycoproteins of SARS-CoV-2 and their respective ACE2 receptors. Further, we conducted a structural analysis of a mink variant S glycoprotein and American mink ACE2 (mvACE2) using cryo-electron microscopy (cryo-EM), revealing four distinct conformations. We discovered a novel intermediary conformation where the mvACE2 receptor is bound to the receptor-binding domain (RBD) of the S glycoprotein in a "down" position, approximately 34° lower than previously reported "up" RBD. Finally, we compared residue interactions in the S-ACE2 complex interface of S glycoprotein conformations with varying RBD orientations. These findings provide valuable insights into the molecular mechanisms of SARS-CoV-2 entry.

COVID-19 and Alzheimer's Disease: Neuroinflammation, Oxidative Stress, Ferroptosis, and Mechanisms Involved.

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by marked cognitive decline, memory loss, and spatio-temporal troubles and, in severe cases, lack of recognition of family members. Neurological symptoms, cognitive disturbances, and the inflammatory frame due to COVID-19, together with long-term effects, have fueled renewed interest in AD based on similar damage. COVID-19 also caused the acceleration of AD symptom onset. In this regard, the morbidity and mortality of COVID-19 were reported to be increased in patients with AD due to multiple pathological changes such as excessive expression of the viral receptor angiotensin-converting enzyme 2 (ACE2), comorbidities such as diabetes, hypertension, or drug-drug interactions in patients receiving polypharmacy and the high presence of proinflammatory molecules. Furthermore, the release of cytokines, neuroinflammation, oxidative stress, and ferroptosis in both diseases showed common underlying mechanisms, which together worsen the clinical picture and prognosis of these patients.

A Naïve Phage Display Library-Derived Nanobody Neutralizes SARS-CoV-2 and Three Variants of Concern.

The emergence of the coronavirus disease 2019 (COVID-19) pandemic and the new severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants of concern (VOCs) requires the continuous development of safe, effective, and affordable prevention and therapeutics. Nanobodies have demonstrated antiviral activity against a variety of viruses, providing a new candidate for the prevention and treatment of SARS-CoV-2 and its variants. SARS-CoV-2 glycoprotein spike 1 subunit (S1) was selected as the target antigen for nanobody screening of a naïve phage display library. We obtained a nanobody, named Nb-H6, and then determined its affinity, inhibition, and stability by ELISA, Competitive ELISA, and Biolayer Interferometry (BLI). Infection assays of authentic and pseudotyped SARS-CoV-2 were performed to evaluate the neutralization of Nb-H6. The structure and mechanism of action were investigated by AlphaFold, docking, and residue mutation assays. We isolated and characterized a nanobody, Nb-H6, which exhibits a broad affinity for S1 and the receptor binding domain (RBD) of SARS-CoV-2, or Alpha (B.1.1.7), Delta (B.1.617.2), Lambda (C.37), and Omicron (BA.2 and BA.5), and blocks receptor angiotensin-converting enzyme 2 (ACE2) binding. Moreover, Nb-H6 can retain its binding capability after pH or thermal treatment and effectively neutralize both pseudotyped and authentic SARS-CoV-2, as well as VOC Alpha (B.1.1.7), Delta (B.1.617.2), and Omicron (BA.2 and BA.5) pseudoviruses. We also confirmed that Nb-H6 binds two distinct amino acid residues of the RBD, preventing SARS-CoV-2 from interacting with the host receptor. Our study highlights a novel nanobody, Nb-H6, that may be useful therapeutically in SARS-CoV-2 and VOC outbreaks and pandemics. These findings also provide a molecular foundation for further studies into how nanobodies neutralize SARS-CoV-2 and variants and imply potential therapeutic targets for the treatment of COVID-19.

Riding the Wave: Unveiling the Conformational Waves from RBD of SARS-CoV-2 Spike Protein to ACE2.

The binding affinity between angiotensin-converting enzyme 2 (ACE2) and the receptor-binding domain (RBD) plays a crucial role in the transmission and reinfection of SARS-CoV2. Here, microsecond molecular dynamics simulations revealed that point mutations in the RBD domain induced conformational transitions that determined the binding affinity between ACE2 and RBD. These structural changes propagated through the RBD domain, altering the orientation of both ACE2 and RBD residues at the binding site. ACE2 receptor shows significant structural heterogeneity, whereas its binding to the RBD domain indicates a much greater degree of structural homogeneity. The receptor was more flexible in its unbound state with the binding of RBD domains inducing structural transitions. The structural heterogeneity observed in the ACE2 unbound form plays a role in the promiscuity of viral entry, as it may allow the receptor to interact with various related and unrelated ligands. Furthermore, rigidity may be important for stabilizing the complex and ensuring the proper orientation of the RBD-binding interface with ACE2. The greater structural homogeneity observed in the ACE2-RBD complex revealed the effectiveness of neutralizing antibodies and vaccines that are primarily directed toward the RBD-binding interface. The binding of the B38 monoclonal antibody revealed restricted conformational transitions in the RBD and ACE2 receptors, attributed to its potent binding interaction.

B-085 Sars-cov-2 nt-chip: A Multiplex eia Platform for Detect Humoral Response and Neutralizing Antibodies Against Sars-cov-2

Abstract Background COVID-19 pandemic is a current health crisis that began in late 2019 and is caused by the pathogen SARS-CoV-2. This virus causes respiratory illness and has led to numerous infections and deaths worldwide. SARS-CoV-2 has an essential protein, the spike protein (S) containing a receptor-binding domain (RBD) binding to the angiotensin-converting enzyme 2 (ACE2) receptor on host cells. Studies have shown that mutations in the RBD can affect its ability to bind to the ACE2 receptor, and some of these mutations have been associated with increased transmissibility or disease severity. During infection, the host immune response can generate a variety of antibodies against SARS-CoV-2 proteins, including neutralizing antibodies that can target RBD. Serological tests could detect the presence of these antibodies in blood samples and are being used to determine whether a person has been infected with SARS-CoV-2 in the past or has developed immunity against the virus after vaccination. These tests also can help to better understand the spreading of new VOCs and epidemiological profiles of COVID-19. However, it is essential to note that the presence of antibodies does not guarantee immunity. Methods SARS-CoV-2 VOC Virachip IgG test was designed for the multiplex detection of binding antibodies to multiple SARS-CoV-2 proteins, including nucleocapsid (N), spike fragment S1 (S1), spike fragment S2 (S2), and the RBDs of Wuhan strain (RBD-w), Delta VOC (RBD-d), and Omicron VOC (RBD-o). This test was modified and further developed to also measure the neutralization effectiveness of antibodies binding against different RBDs. The percentage of inhibition of neutralizing antibodies against Wuhan and Omicron RBDs was determined. To achieve this, a purified ACE-2 Alkaline-Phosphatase conjugate was incorporated into the assay, and its ability to bind RBD spots in the microarray wells was measured after preincubation with sera or plasma. The presence of neutralizing antibodies was assessed for its capability of preventing such interaction, hence allowing us to detect neutralizing antibodies indirectly. Furthermore, it was also possible to generally detect binding antibodies against RBDs and the N protein. Assessing past infections in people immunized with mRNA vaccines, and in the same assay, detecting the subset of antibodies that promote functional neutralization against SARS-CoV-2 infection was feasible. Results A cohort containing 50 pre-pandemic and 61 post-infection sera the SARS-CoV-2 NT-CHIP yielded 100% specificity and 96.7% sensitivity regarding neutralization antibodies against RBD-w. In case of RBD-o analysis of 111 serum samples from patients before the emergence of Omicron and 69 serum samples from patients after infection resulted in 99.1% specifictiy and 95.7% sensitivity. These tests were performed in comparison with PRNT, the gold standard test for measuring neutralization. Conclusion This innovative microarray platform allows for quick upgrades to incorporate new RBDs from currently important VOCs. Given the status of the pandemic, the emergence of new variant strains, and vaccine adjustments, the SARS-COV-2 NT-CHIP could be a very valuable tool for assessing the humoral immunity generated against future VOCs. Thus, it contributes to the decision-making processes in the public health care system and is well suited for new vaccine studies.

The influence of SARS-CoV-2 on male reproduction and men's health.

SARS-CoV-2, the virus responsible for COVID-19, primarily affects the respiratory system by targeting the Angiotensin-converting enzyme 2 (ACE2) receptor and TMPRSS2. However, these receptors are also present in other organs, including the testes, where a higher concentration of ACE2 receptors has been observed. This raises concerns about the potential impact of the virus on male fertility. In this study, we aimed to assess the effects of SARS-CoV-2 on semen parameters by comparing samples during and after infection in the same patients. The study enrolled 51 individuals who had contracted COVID-19 and analysed various parameters related to sperm quality and quantity, including C-reactive protein, testosterone levels, total sperm concentration, motility and morphology. A comparison was made between these parameters during the initial infection with SARS-CoV-2 and after a 2- and 5-month recovery period. The results indicated that all of the mentioned parameters were significantly affected during COVID-19 infection (PCR-ct, CRP, WBCs LH, FSH and testosterone levels, p-value = .0001). Furthermore, the study assessed TC, TM and sperm morphology in patients infected with SARS-CoV-2 and found that these parameters were also significantly influenced during the infection, (p-value = .0001; Morphology, p-value = .0004). We observed significant alterations in sperm count and morphology during infection, suggesting a potential negative impact on sperm quality. Additionally, lower hormone levels were observed during COVID-19 infection, possibly due to increased inflammatory cytokines. However, both hormones and inflammation markers returned to normal following recovery. Our findings indicate a statistically significant change in total sperm count, motility and morphology post-infection, which aligns with previous studies. Discussion, COVID-19 have a transient impact on sperm parameters and fertility, emphasizing the importance of further investigation into the long-term implications.

Computational redesign of Beta-27 Fab with substantially better predicted binding affinity to the SARS-CoV-2 Omicron variant than human ACE2 receptor

During the COVID-19 pandemic, SARS-CoV-2 has caused large numbers of morbidity and mortality, and the Omicron variant (B.1.1.529) was an important variant of concern. To enter human cells, the receptor-binding domain (RBD) of the S1 subunit of SARS-CoV-2 (SARS-CoV-2-RBD) binds to the peptidase domain (PD) of Angiotensin-converting enzyme 2 (ACE2) receptor. Disrupting the binding interactions between SARS-CoV-2-RBD and ACE2-PD using neutralizing antibodies is an effective COVID-19 therapeutic solution. Previous study found that Beta-27 Fab, which was obtained by digesting the full IgG antibodies that were isolated from a patient infected with SARS-CoV-2 Beta variant, can neutralize Victoria, Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), and Delta (B.1.617.2) variants. This study employed computational protein design and molecular dynamics (MD) to investigate and enhance the binding affinity of Beta-27 Fab to SARS-CoV-2-RBD Omicron variant. MD results show that five best designed Beta-27 Fabs (Beta-27-D01 Fab, Beta-27-D03 Fab, Beta-27-D06 Fab, Beta-27-D09 Fab and Beta-27-D10 Fab) were predicted to bind to Omicron RBD in the area, where ACE2 binds, with significantly better binding affinities than Beta-27 Fab and ACE2. Their enhanced binding affinities are mostly caused by increased binding interactions of CDR L2 and L3. They are promising candidates that could potentially be employed to disrupt the binding between ACE2 and Omicron RBD.

Structure-Activity Relationship of Novel ACE Inhibitory Undecapeptides from Stropharia rugosoannulata by Molecular Interactions and Activity Analyses.

Undecapeptide is the central peptide molecule in the peptide base material of Stropharia rugosoannulata, and angiotensin-converting enzyme (ACE) plays a crucial role in hypertension. To fully explore the interaction mechanism and ACE-inhibitory activity of long-chain peptides from Stropharia rugosoannulata, the binding conformations of twenty-seven undecapeptides with the ACE receptor were revealed by molecule docking. The undecapeptide GQEDYDRLRPL with better receptor binding capacity and higher secondary mass spectral abundance was screened. All amino acid residues except proline in GQEDYDRLRPL interacted with the ACE receptor. GQEDYDRLRPL interfered with the receptor's overall structure, with significant fluctuations in amino acid residues 340-355, including two residues in the receptor's active pockets. The binding constants of GQEDYDRLRPL to the ACE receptors were at the μM level, with a kinetic binding constant of 9.26 × 10-7 M, which is a strong binding, and a thermodynamic binding constant of 3.06 × 10-6 M. Intermolecular interaction were exothermic, enthalpy-driven, and specific binding reactions. GQEDYDRLRPL had an IC50 value of 164.41 μmol/L in vitro and superior antihypertensive effects at low-gavage administration in vivo. Obtaining information on the interaction mechanism of ACE-inhibitory undecapeptides from S. rugosoannulata with the ACE receptor will help to develop and utilize ACE inhibitors of natural origin.

A prospective study of extraesophageal reflux and potential microaspiration in patients hospitalized with COVID-19 in Jordan

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lung infection has represented a global challenge. Intriguingly, it has been shown that the alveolar lung epithelium expresses little Angiotensin Converting Enzyme receptor protein (ACE2), the entry receptor for SARS-CoV-2. Upper airway establishment of infection and translocation to the lung is well documented but other anatomical niches may be relevant to potentially serious lung infection. ACE2 is heavily expressed in the gastrointestinal tract and gastrointestinal symptoms support a clinical diagnosis of Coronavirus disease 2019 (COVID-19). This suggests a research question and the need to gather patient data exploring potential aerodigestive links in SARS-CoV-2 tranlocation and infection which may be relevant in the peripheral lung. This recognizes anatomical proximity and concepts of bi-directional movement between the Gastrointestinal and lung systems in normal physiology and disease. We have therefore explored the potential for gastro oesophageal reflux disease (GORD) micro aspiration and aeorodigestive pathophysiology in a novel prospective investigation of patients hospitalized with COVID-19.MethodsThis is a prospective descriptive cohort study of 210 patients who were hospitalized with a confirmed diagnosis of COVID-19. The cohort was divided into three groups of patients based on symptom severity and radiological results. The Reflux Symptom Index (RSI) was used to evaluate the presence and severity of GOR. An RSI greater than 13 is considered to be abnormal. Patients’ saliva samples were tested using enzyme-linked immunosorbent assay (ELISA) to determine the level of salivary pepsin among the cohort of patients.ResultsA total of 210 patients with COVID-19 were enrolled in the study with 55.2% (116/210) classified as mildly ill, 31.9% (67/210) moderately ill and 12.9% (27/210) as severely ill. 34% (72/210) of the patients had an RSI score of over 13 and a median salivary pepsin value of 54 ± 29 ng/ml which suggested an incidence of extraesophageal reflux (EOR) in around a third of patients. The presence of respiratory comorbid conditions, an RSI score of over 13 and a salivary pepsin level of > 76ng/ml increased the risk of developing a more severe COVID-19 infection.ConclusionThe study showed a high prevalence of EOR among the study cohort and provide the first prospective evidence suggesting the potential for aerodigestive pathophysiology including microaspiration in COVID-19 disease. We believe that the results of our study support the need for more extensive research.

Effects of the glycosylation of the receptor binding domain (RBD dimer)-based Covid-19 vaccine (ZF2001) on its humoral immunogenicity and immunoreactivity

The SARS-CoV-2 spike protein receptor-binding domain (RBD), which is a key target for the development of SARS-CoV-2 neutralizing antibodies and vaccines, mediates the binding of the host receptor angiotensin-converting enzyme 2 (ACE2). However, the high heterogeneity of RBD glycoforms may lead to an incomplete neutralization effect and impact the immunogenicity of RBD-based vaccines (Ye et al., 2021). Here, our data suggested that the glycosylation significantly affected the humoral immunogenicity and immunoreactivity of the RBD-dimer-based Covid-19 vaccine (ZF2001) (Yang et al., 2021). Several deglycosylated types of ZF2001 (with sialic acid removed (ZF2001-ΔSA), sialic acid & O-glycans removed (ZF2001-ΔSA&O), N-glycans removed (ZF2001-ΔN), N- & O-glycans removed (ZF2001-ΔN&O)) were obtained by treatment with glycosidases. The binding affinity between deglycosylated types of ZF2001 and ACE2 was slightly weakened and that between deglycosylated types of ZF2001 and several monoclonal antibodies (mAbs) were also changed compared with ZF2001. The results of pseudovirus neutralization assay and binding affinity assay of all ZF2001 types revealed that the antigens with complex glycosylation had better humoral immunogenicity and immunoreactivity. Molecular dynamics simulation indicated that the more complex glycosylation of RBD corresponded to more hydrogen bonds formed between helper T-cell epitopes of RBD and major histocompatibility complex II (MHC-II). In summary, these results demonstrated that the glycosylation of RBD affects antigen presentation, humoral immunogenicity and immunoreactivity, which may be an important consideration for vaccine design and production technology.

COVID-19 and Long COVID: Disruption of the Neurovascular Unit, Blood-Brain Barrier, and Tight Junctions

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), could affect brain structure and function. SARS-CoV-2 can enter the brain through different routes, including the olfactory, trigeminal, and vagus nerves, and through blood and immunocytes. SARS-CoV-2 may also enter the brain from the peripheral blood through a disrupted blood-brain barrier (BBB). The neurovascular unit in the brain, composed of neurons, astrocytes, endothelial cells, and pericytes, protects brain parenchyma by regulating the entry of substances from the blood. The endothelial cells, pericytes, and astrocytes highly express angiotensin converting enzyme 2 (ACE2), indicating that the BBB can be disturbed by SARS-CoV-2 and lead to derangements of tight junction and adherens junction proteins. This leads to increased BBB permeability, leakage of blood components, and movement of immune cells into the brain parenchyma. SARS-CoV-2 may also cross microvascular endothelial cells through an ACE2 receptor–associated pathway. The exact mechanism of BBB dysregulation in COVID-19/neuro-COVID is not clearly known, nor is the development of long COVID. Various blood biomarkers could indicate disease severity and neurologic complications in COVID-19 and help objectively diagnose those developing long COVID. This review highlights the importance of neurovascular and BBB disruption, as well as some potentially useful biomarkers in COVID-19, and long COVID/neuro-COVID.