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Comparative Study: Four SARS-CoV-2 vaccines induce quantitatively different antibody responses against SARS-CoV-2 variants
Reporter: Aviva Lev- Ari, PhD, RN
Marit J. van Gils, A. H. Ayesha Lavell, Karlijn van der Straten, Brent Appelman, Ilja Bontjer, Meliawati Poniman, Judith A. Burger, Melissa Oomen, Joey H. Bouhuijs, Lonneke A. van Vught, Marleen A. Slim, Michiel Schinkel, Elke Wynberg, Hugo D.G. van Willigen, Marloes Grobben, Khadija Tejjani, Jonne Snitselaar, Tom G. Caniels, Amsterdam UMC COVID-19 S3/HCW study group, Alexander P. J. Vlaar, Maria Prins, Menno D. de Jong, Godelieve J. de Bree, Jonne J. Sikkens, Marije K. Bomers, Rogier W. Sanders doi:https://doi.org/10.1101/2021.09.27.21264163
Abstract
Emerging and future SARS-CoV-2 variants may jeopardize the effectiveness of vaccination campaigns. We performed a head-to-head comparison of the ability of sera from individuals vaccinated with either one of four vaccines (BNT162b2, mRNA-1273, AZD1222 or Ad26.COV2.S) to recognize and neutralize the four SARS-CoV-2 variants of concern (VOCs; Alpha, Beta, Gamma and Delta). Four weeks after completing the vaccination series, SARS-CoV-2 wild-type neutralizing antibody titers were highest in recipients of BNT162b2 and mRNA-1273 (median titers of 1891 and 3061, respectively), and substantially lower in those vaccinated with the adenovirus vector-based vaccines AZD1222 and Ad26.COV2.S (median titers of 241 and 119, respectively). VOCs neutralization was reduced in all vaccine groups, with the largest (5.8-fold) reduction in neutralization being observed against the Beta variant. Overall, the mRNA vaccines appear superior to adenovirus vector-based vaccines in inducing neutralizing antibodies against VOCs four weeks after the final vaccination.
Figure 2:Binding and neutralization titers post-vaccination against VOCs.
(A) Median with interquartile range of binding titers to wild-type and VOCs S proteins represented as mean fluorescence intensity (MFI) of 1:100,000 diluted sera collected four-five weeks after full vaccination for the four vaccination groups. The lower cutoff for binding was set at an MFI of 10 (grey shading). Vaccine groups are indicated by colors with BNT162b2 in green, mRNA-1273 in purple, AZD1222 in orange and Ad26.COV2.S in blue. (B) Median with interquartile range of half-maximal neutralization (ID50) titers of D614G and VOCs pseudoviruses for sera collected after full vaccination for the four vaccination groups. The lower cutoff for neutralization was set at an ID50 of 100 (grey shading). Vaccine groups are indicated by colors with BNT162b2 in green, mRNA-1273 in purple, AZD1222 in orange and Ad26.COV2.S in blue. (C) Median ID50 neutralization of D614G and VOCs plotted against the reported vaccine efficacy against symptomatic infection2–5,12–17. Vaccine groups are indicated by colors with BNT162b2 in green, mRNA-1273 in purple, AZD1222 in orange and Ad26.COV2.S in blue. Circles represent WT data, squares for Alpha, diamond for Beta, nabla triangle for Gamma and delta triangle for Delta. Spearman’s rank correlation coefficient with p value are indicated. The result of the AZD1222 phase 3 trial conducted in South Africa, demonstrating poor (10%) efficacy against Beta variant, is not shown.
Ramatroban, a Thromboxane A2/TPr and PGD2/DPr2 receptor antagonist for Acute and Long haul COVID-19
Author: Ajay Gupta, MD
From: “Gupta, Ajay” <ajayg1@hs.uci.edu> Date: Wednesday, July 7, 2021 at 1:10 PM To: Aviva Lev-Ari <AvivaLev-Ari@alum.berkeley.edu> Cc: “Dr. Saul Yedgar” <saulye@ekmd.huji.ac.il> Subject: Ramatroban, a Thromboxane A2/TPr and PGD2/DPr2 receptor antagonist for Acute and Long haul COVID-19
While corticosteroids may have a role in about 5% of hospitalized patients who have the cytokine storm, currently there is no effective treatment for mild or moderate COVID and long haul COVID. Massive increase in respiratory and plasma thromboxane A2 (TxA2) plays a key role in thromboinflammation and microvascular thrombosis, while an increase in respiratory and plasma PGD2 potentially suppresses innate interferon response, and acquired Th1 anti-viral response, while promoting a maladaptive type 2, anti-helminthic like immune response. Ramatroban is a potent dual receptor antagonist of Thromboxane A2/TPr and PGD2/DPr2 that has been used in Japan for the treatment of allergic rhinitis for past 20 years (Baynas®, Bayer Japan). We first disclosed use of ramatroban for COVID in a provisional patent application filed on 31st March, 2020; followed by the publication Gupta et al, J Mol Genet Med, 2020
Several experts, as outlined below in yellow highlighted text, have supported the idea of using ramatroban as an anti-thrombotic and immunomodulator in COVID-19.
1. Prof. Louis Flamand, Nicolas Flamand, Eric Boilard Laval Univ. Quebec, Canada: There is a lipid-mediator storm in COVID-19 characterized by massive increases in thromboxane A2 and PGD2 in the lungs and plasma. “Blocking the deleterious effects of PGD2 and TxA2 with the dual DPr2/TPr antagonist Ramatroban might be beneficial in COVID-19Archambault et al, FASEB, June 2021, doi: https://doi.org/10.1096/fj.202100540R
2. Prof. Garret A FitzGerald, Univ. Of Pennsylvania, Member National Academy of Sciences.https://en.wikipedia.org/wiki/Garret_A._FitzGerald “In the current pandemic there may be utility in targeting eicosanoids with existing drugs. These approaches would likely be most effective early in the disease before the development of ARDS, where cytokines and chemokines dominate. Dexamethasone limits COX-2 expression and might diminish COVID-19 severity and mortality at least in part, by diminishing COX metabolites… Dexamethasone might improve severe COVID-19 by diminishing the prostaglandins / thromboxane storm in the lungs”. “Treatment with a PGD2/DPr2 inhibitor decreased viral load and improved morbidity by upregulating IFN-lambda expression. ….. Antagonism of the thromboxane receptor (TPr) prevents ARDS…. Early administration of well-tolerated TPr antagonists may limit progress to severe COVID-19 (Theken and FitzGerald, Science, 2021)
4. Prof. Simon Phipps, Univ. of Queensland, Brisbane Australia “It has been hypothesized that DP2 antagonists be repurposed as a novel immunotherapy for the treatment of COVID-19, and this may be appropriate in mild to moderate cases where Th1 immunity is impaired.” (Ullah et al, Mucosal Immunology, 2021)
5. Prof. Bruce D. Hammock, Distinguished Professor, Univ of California Davis, Member US National Academy of Sciences and National Academy of Inventors; April 25, 2021. https://www.entsoc.org/fellows/hammock “I find your idea of blocking specific thromboxane receptors in preventing or reducing some of the devastating co-morbidity of COVID-19 very compelling. … A DPr2 receptor blocker is conceptually attractive in offering the potential of effective therapy and low risk due to a high therapeutic index.” E mail dated April 25, 2021.(https://ajp.amjpathol.org/action/showPdf?pii=S0002-9440%2820%2930332-1 and http://ucanr.edu/sites/hammocklab/files/328012.pdf)
6. Ann E Eakin, PhD, Senior Scientific Officer, NIH-NIAID “very compelling data supporting potential benefits of ramatroban in both reducing viral load as well as modulating host responses” E Mail dated Nov 20, 2020
Ramatroban is expected to reduce lung fibrosis in COVID-19 and therefore diminish clinical manifestations of Long haul COVID. Pang et al, 2021 “examined the effect of Ramatroban, a clinical antagonist of both PGD2 and TXA2 receptors, on treating silicosis using a mouse model. The results showed that Ramatroban significantly alleviated silica-induced pulmonary inflammation, fibrosis, and cardiopulmonary dysfunction compared with the control group.” https://www.thno.org/v11p2381.htm
Unfortunately, the animal models of COVID-19 are harsh, lack microvascular thrombosis and immune perturbations characteristic of human disease. These models may be good for testing antivirals but not for testing immunomodulators or anti-thrombotics. There is highly positive anecdotal experience with use of ramatroban in moderately severe COVID-19 (https://www.researchsquare.com/article/rs-474882/v1
Nir Hacohen and Marcia Goldberg, Researchers at MGH and the Broad Institute identify protein “signature” of severe COVID-19
Curator and Reporter: Aviva Lev-Ari, PhD, RN
Longitudinal proteomic analysis of plasma from patients with severe COVID-19 reveal patient survival-associated signatures, tissue-specific cell death, and cell-cell interactions
16% of COVID-19 patients display an atypical low-inflammatory plasma proteome
Severe COVID-19 is associated with heterogeneous plasma proteomic responses
Death of virus-infected lung epithelial cells is a key feature of severe disease
Lung monocyte/macrophages drive T cell activation, together promoting epithelial damage
Summary
Mechanisms underlying severe COVID-19 disease remain poorly understood. We analyze several thousand plasma proteins longitudinally in 306 COVID-19 patients and 78 symptomatic controls, uncovering immune and non-immune proteins linked to COVID-19. Deconvolution of our plasma proteome data using published scRNAseq datasets reveals contributions from circulating immune and tissue cells. Sixteen percent of patients display reduced inflammation yet comparably poor outcomes. Comparison of patients who died to severely ill survivors identifies dynamic immune cell-derived and tissue-associated proteins associated with survival, including exocrine pancreatic proteases. Using derived tissue-specific and cell type-specific intracellular death signatures, cellular ACE2 expression, and our data, we infer whether organ damage resulted from direct or indirect effects of infection. We propose a model in which interactions among myeloid, epithelial, and T cells drive tissue damage. These datasets provide important insights and a rich resource for analysis of mechanisms of severe COVID-19 disease.
The quest to identify mechanisms that might be contributing to death in COVID-19: Why do some patients die from this disease, while others — who appear to be just as ill do not?
Researchers at Massachusetts General Hospital (MGH) and the Broad Institute of MIT and Harvard have identified the protein “signature” of severe COVID-19
Interest was to develop methods for studying human immune responses to infections, which they had applied to the condition known as bacterial sepsis. The three agreed to tackle this new problem with the goal of understanding how the human immune system responds to SARS-CoV-2, the novel pathogen that causes COVID-19.
How scientists launched a study in days to probe COVID-19’s unpredictability
Collecting these specimens required a large team of collaborators from many departments, which worked overtime for five weeks to amass blood samples from 306 patients who tested positive for COVID-19, as well as from 78 patients with similar symptoms who tested negative for the coronavirus.
Credit : Alexandra-Chloé VillaniResearch associates at Mass General who worked countless hours to process blood samples for the COVID Acute Cohort Study (from left to right: Anna Gonye, Irena Gushterova, and Tom Lasalle)By Leah Eisenstadt
As the COVID-19 surge began in March, Mass General and Broad researchers worked around the clock to begin learning why some patients fare worse with the disease than others
The study found that most patients with COVID-19 have a consistent protein signature, regardless of disease severity; as would be expected, their bodies mount an immune response by producing proteins that attack the virus. “But we also found a small subset of patients with the disease who did not demonstrate the pro-inflammatory response that is typical of other COVID-19 patients,” Filbin said, yet these patients were just as likely as others to have severe disease. Filbin, who is also an assistant professor of emergency medicine at Harvard Medical School (HMS), noted that patients in this subset tended to be older people with chronic diseases, who likely had weakened immune systems.
Among other revelations, this showed that the most prevalent severity-associated protein, a pro-inflammatory protein called interleukin-6 (IL-6) rose steadily in patients who died, while it rose and then dropped in those with severe disease who survived. Early attempts by other groups to treat COVID-19 patients experiencing acute respiratory distress with drugs that block IL-6 were disappointing, though more recent studies show promise in combining these medications with the steroid dexamethasone.
Hacohen, who is a professor of medicine at HMS and director of the Broad’s Cell Circuits Program:
“You can ask which of the many thousands of proteins that are circulating in your blood are associated with the actual outcome,” he said, “and whether there is a set of proteins that tell us something.”
Goldberg, who is a professor of emergency medicine at HMS:
They are highly likely to be useful in figuring out some of the underlying mechanisms that lead to severe disease and death in COVID-19,” she said, noting her gratitude to the patients involved in the study. Their samples are already being used to study other aspects of COVID-19, such as identifying the qualities of antibodies that patients form against the virus.
Thriving Vaccines and Research: Weizmann Institute Coronavirus Research Development
Reporter:Amandeep Kaur, B.Sc., M.Sc.
In early February, Prof. Eran Segal updated in one of his tweets and mentioned that “We say with caution, the magic has started.”
The article reported that this statement by Prof. Segal was due to decreasing cases of COVID-19, severe infection cases and hospitalization of patients by rapid vaccination process throughout Israel. Prof. Segal emphasizes in another tweet to remain cautious over the country and informed that there is a long way to cover and searching for scientific solutions.
A daylong webinar entitled “COVID-19: The epidemic that rattles the world” was a great initiative by Weizmann Institute to share their scientific knowledge about the infection among the Israeli institutions and scientists. Prof. Gideon Schreiber and Dr. Ron Diskin organized the event with the support of the Weizmann Coronavirus Response Fund and Israel Society for Biochemistry and Molecular Biology. The speakers were invited from the Hebrew University of Jerusalem, Tel-Aviv University, the Israel Institute for Biological Research (IIBR), and Kaplan Medical Center who addressed the molecular structure and infection biology of the virus, treatments and medications for COVID-19, and the positive and negative effect of the pandemic.
The article reported that with the emergence of pandemic, the scientists at Weizmann started more than 60 projects to explore the virus from different range of perspectives. With the help of funds raised by communities worldwide for the Weizmann Coronavirus Response Fund supported scientists and investigators to elucidate the chemistry, physics and biology behind SARS-CoV-2 infection.
Prof. Avi Levy, the coordinator of the Weizmann Institute’s coronavirus research efforts, mentioned “The vaccines are here, and they will drastically reduce infection rates. But the coronavirus can mutate, and there are many similar infectious diseases out there to be dealt with. All of this research is critical to understanding all sorts of viruses and to preempting any future pandemics.”
The following are few important projects with recent updates reported in the article.
Mapping a hijacker’s methods
Dr. Noam Stern-Ginossar studied the virus invading strategies into the healthy cells and hijack the cell’s systems to divide and reproduce. The article reported that viruses take over the genetic translation system and mainly the ribosomes to produce viral proteins. Dr. Noam used a novel approach known as ‘ribosome profiling’ as her research objective and create a map to locate the translational events taking place inside the viral genome, which further maps the full repertoire of viral proteins produced inside the host.
She and her team members grouped together with the Weizmann’s de Botton Institute and researchers at IIBR for Protein Profiling and understanding the hijacking instructions of coronavirus and developing tools for treatment and therapies. Scientists generated a high-resolution map of the coding regions in the SARS-CoV-2 genome using ribosome-profiling techniques, which allowed researchers to quantify the expression of vital zones along the virus genome that regulates the translation of viral proteins. The study published in Nature in January, explains the hijacking process and reported that virus produces more instruction in the form of viral mRNA than the host and thus dominates the translation process of the host cell. Researchers also clarified that it is the misconception that virus forced the host cell to translate its viral mRNA more efficiently than the host’s own translation, rather high level of viral translation instructions causes hijacking. This study provides valuable insights for the development of effective vaccines and drugs against the COVID-19 infection.
Like chutzpah, some things don’t translate
Prof. Igor Ulitsky and his team worked on untranslated region of viral genome. The article reported that “Not all the parts of viral transcript is translated into protein- rather play some important role in protein production and infection which is unknown.” This region may affect the molecular environment of the translated zones. The Ulitsky group researched to characterize that how the genetic sequence of regions that do not translate into proteins directly or indirectly affect the stability and efficiency of the translating sequences.
Initially, scientists created the library of about 6,000 regions of untranslated sequences to further study their functions. In collaboration with Dr. Noam Stern-Ginossar’s lab, the researchers of Ulitsky’s team worked on Nsp1 protein and focused on the mechanism that how such regions affect the Nsp1 protein production which in turn enhances the virulence. The researchers generated a new alternative and more authentic protocol after solving some technical difficulties which included infecting cells with variants from initial library. Within few months, the researchers are expecting to obtain a more detailed map of how the stability of Nsp1 protein production is getting affected by specific sequences of the untranslated regions.
The landscape of elimination
The article reported that the body’s immune system consists of two main factors- HLA (Human Leukocyte antigen) molecules and T cells for identifying and fighting infections. HLA molecules are protein molecules present on the cell surface and bring fragments of peptide to the surface from inside the infected cell. These peptide fragments are recognized and destroyed by the T cells of the immune system. Samuels’ group tried to find out the answer to the question that how does the body’s surveillance system recognizes the appropriate peptide derived from virus and destroy it. They isolated and analyzed the ‘HLA peptidome’- the complete set of peptides bound to the HLA proteins from inside the SARS-CoV-2 infected cells.
After the analysis of infected cells, they found 26 class-I and 36 class-II HLA peptides, which are present in 99% of the population around the world. Two peptides from HLA class-I were commonly present on the cell surface and two other peptides were derived from coronavirus rare proteins- which mean that these specific coronavirus peptides were marked for easy detection. Among the identified peptides, two peptides were novel discoveries and seven others were shown to induce an immune response earlier. These results from the study will help to develop new vaccines against new coronavirus mutation variants.
Gearing up ‘chain terminators’ to battle the coronavirus
Prof. Rotem Sorek and his lab discovered a family of enzymes within bacteria that produce novel antiviral molecules. These small molecules manufactured by bacteria act as ‘chain terminators’ to fight against the virus invading the bacteria. The study published in Nature in January which reported that these molecules cause a chemical reaction that halts the virus’s replication ability. These new molecules are modified derivates of nucleotide which integrates at the molecular level in the virus and obstruct the works.
Prof. Sorek and his group hypothesize that these new particles could serve as a potential antiviral drug based on the mechanism of chain termination utilized in antiviral drugs used recently in the clinical treatments. Yeda Research and Development has certified these small novel molecules to a company for testing its antiviral mechanism against SARS-CoV-2 infection. Such novel discoveries provide evidences that bacterial immune system is a potential repository of many natural antiviral particles.
Resolving borderline diagnoses
Currently, Real-time Polymerase chain reaction (RT-PCR) is the only choice and extensively used for diagnosis of COVID-19 patients around the globe. Beside its benefits, there are problems associated with RT-PCR, false negative and false positive results and its limitation in detecting new mutations in the virus and emerging variants in the population worldwide. Prof. Eran Elinavs’ lab and Prof. Ido Amits’ lab are working collaboratively to develop a massively parallel, next-generation sequencing technique that tests more effectively and precisely as compared to RT-PCR. This technique can characterize the emerging mutations in SARS-CoV-2, co-occurring viral, bacterial and fungal infections and response patterns in human.
The scientists identified viral variants and distinctive host signatures that help to differentiate infected individuals from non-infected individuals and patients with mild symptoms and severe symptoms.
In Hadassah-Hebrew University Medical Center, Profs. Elinav and Amit are performing trails of the pipeline to test the accuracy in borderline cases, where RT-PCR shows ambiguous or incorrect results. For proper diagnosis and patient stratification, researchers calibrated their severity-prediction matrix. Collectively, scientists are putting efforts to develop a reliable system that resolves borderline cases of RT-PCR and identify new virus variants with known and new mutations, and uses data from human host to classify patients who are needed of close observation and extensive treatment from those who have mild complications and can be managed conservatively.
Moon shot consortium refining drug options
The ‘Moon shot’ consortium was launched almost a year ago with an initiative to develop a novel antiviral drug against SARS-CoV-2 and was led by Dr. Nir London of the Department of Chemical and Structural Biology at Weizmann, Prof. Frank von Delft of Oxford University and the UK’s Diamond Light Source synchroton facility.
To advance the series of novel molecules from conception to evidence of antiviral activity, the scientists have gathered support, guidance, expertise and resources from researchers around the world within a year. The article reported that researchers have built an alternative template for drug-discovery, full transparency process, which avoids the hindrance of intellectual property and red tape.
The new molecules discovered by scientists inhibit a protease, a SARS-CoV-2 protein playing important role in virus replication. The team collaborated with the Israel Institute of Biological Research and other several labs across the globe to demonstrate the efficacy of molecules not only in-vitro as well as in analysis against live virus.
Further research is performed including assaying of safety and efficacy of these potential drugs in living models. The first trial on mice has been started in March. Beside this, additional drugs are optimized and nominated for preclinical testing as candidate drug.
Cryo-EM disclosed how the D614G mutation changes SARS-CoV-2 spike protein structure.
Reporter: Dr. Premalata Pati, Ph.D., Postdoc
SARS-CoV-2, the virus that causes COVID-19, has had a major impact on human health globally; infecting a massive quantity of people around 136,046,262 (John Hopkins University); causing severe disease and associated long-term health sequelae; resulting in death and excess mortality, especially among older and prone populations; altering routine healthcare services; disruptions to travel, trade, education, and many other societal functions; and more broadly having a negative impact on peoples physical and mental health.
It’s need of the hour to answer the questions like what allows the variants of SARS-CoV-2 first detected in the UK, South Africa, and Brazil to spread so quickly? How can current COVID-19 vaccines better protect against them?
Bing Chen, HMS professor of pediatrics at Boston Children’s, and colleagues analyzed the changes in the structure of the spike proteins with the genetic change by D614G mutation by all three variants. Hence they assessed the structure of the coronavirus spike protein down to the atomic level and revealed the reason for the quick spreading of these variants.
This model shows the structure of the spike protein in its closed configuration, in its original D614 form (left) and its mutant form (G614). In the mutant spike protein, the 630 loop (in red) stabilizes the spike, preventing it from flipping open prematurely and rendering SARS-CoV-2 more infectious.
Fig. 1. Cryo-EM structures of the full-length SARS-CoV-2 S protein carrying G614.
(A) Three structures of the G614 S trimer, representing a closed, three RBD-down conformation, an RBD-intermediate conformation and a one RBD-up conformation, were modeled based on corresponding cryo-EM density maps at 3.1-3.5Å resolution. Three protomers (a, b, c) are colored in red, blue and green, respectively. RBD locations are indicated. (B) Top views of superposition of three structures of the G614 S in (A) in ribbon representation with the structure of the prefusion trimer of the D614 S (PDB ID: 6XR8), shown in yellow. NTD and RBD of each protomer are indicated. Side views of the superposition are shown in fig. S8.
The mutant spikes were imaged by Cryo-Electron microscopy (cryo-EM), which has resolution down to the atomic level. They found that the D614G mutation (substitution of in a single amino acid “letter” in the genetic code for the spike protein) makes the spike more stable as compared with the original SARS-CoV-2 virus. As a result, more functional spikes are available to bind to our cells’ ACE2 receptors, making the virus more contagious.
Fig. 2. Cryo-EM revealed how the D614G mutation changes SARS-CoV-2 spike protein structure.
Say the original virus has 100 spikes,” Chen explained. “Because of the shape instability, you may have just 50 percent of them functional. In the G614 variants, you may have 90 percent that is functional. So even though they don’t bind as well, the chances are greater and you will have an infection
Forthcoming directions by Bing Chen and Team
The findings suggest the current approved COVID-19 vaccines and any vaccines in the works should include the genetic code for this mutation. Chen has quoted:
Since most of the vaccines so far—including the Moderna, Pfizer–BioNTech, Johnson & Johnson, and AstraZeneca vaccines are based on the original spike protein, adding the D614G mutation could make the vaccines better able to elicit protective neutralizing antibodies against the viral variants
Chen proposes that redesigned vaccines incorporate the code for this mutant spike protein. He believes the more stable spike shape should make any vaccine based on the spike more likely to elicit protective antibodies. Chen also has his sights set on therapeutics. He and his colleagues are further applying structural biology to better understand how SARS-CoV-2 binds to the ACE2 receptor. That could point the way to drugs that would block the virus from gaining entry to our cells.
In January, the team showed that a structurally engineered “decoy” ACE2 protein binds to SARS-CoV-2 200 times more strongly than the body’s own ACE2. The decoy potently inhibited the virus in cell culture, suggesting it could be an anti-COVID-19 treatment. Chen is now working to advance this research into animal models.
Main Source:
Abstract
Substitution for aspartic acid by glycine at position 614 in the spike (S) protein of severe acute respiratory syndrome coronavirus 2 appears to facilitate rapid viral spread. The G614 strain and its recent variants are now the dominant circulating forms. We report here cryo-EM structures of a full-length G614 S trimer, which adopts three distinct prefusion conformations differing primarily by the position of one receptor-binding domain. A loop disordered in the D614 S trimer wedges between domains within a protomer in the G614 spike. This added interaction appears to prevent premature dissociation of the G614 trimer, effectively increasing the number of functional spikes and enhancing infectivity, and to modulate structural rearrangements for membrane fusion. These findings extend our understanding of viral entry and suggest an improved immunogen for vaccine development.
Comparing COVID-19 Vaccine Schedule Combinations, or “Com-COV” – First-of-its-Kind Study will explore the Impact of using eight different Combinations of Doses and Dosing Intervals for Different COVID-19 Vaccines
This study examined whether CD8+ T-cell responses from COVID-19 convalescent individuals (n=30) potentially maintain recognition of the major SARS-CoV-2 variants (n=45 mutations assessed). Only one mutation found in B.1.351-Spike overlapped with a previously identified epitope (1/52), suggesting that virtually all anti-SARS-CoV-2 CD8+ T-cell responses should recognize these newly described variants.
Andrew D Redd, Alessandra Nardin, Hassen Kared, Evan M Bloch, Andrew Pekosz, Oliver Laeyendecker, Brian Abel, Michael Fehlings, Thomas C Quinn, Aaron A R Tobian, CD8+ T cell responses in COVID-19 convalescent individuals target conserved epitopes from multiple prominent SARS-CoV-2 circulating variants, Open Forum Infectious Diseases, 2021;, ofab143, https://doi.org/10.1093/ofid/ofab143
Tuesday, March 30, 2021
T cells recognize recent SARS-CoV-2 variants
Scanning electron micrograph of a human T lymphocyte (also called a T cell) from the immune system of a healthy donor. NIAID
What
When variants of SARS-CoV-2 (the virus that causes COVID-19) emerged in late 2020, concern arose that they might elude protective immune responses generated by prior infection or vaccination, potentially making re-infection more likely or vaccination less effective. To investigate this possibility, researchers from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and colleagues analyzed blood cell samples from 30 people who had contracted and recovered from COVID-19 prior to the emergence of virus variants. They found that one key player in the immune response to SARS-CoV-2—the CD8+ T cell—remained active against the virus.
The research team was led by NIAID’s Andrew Redd, Ph.D., and included scientists from Johns Hopkins University School of Medicine, Johns Hopkins Bloomberg School of Public Health and the Immunomics-focused company, ImmunoScape.
The investigators asked whether CD8+ T cells in the blood of recovered COVID-19 patients, infected with the initial virus, could still recognize three SARS-CoV-2 variants: B.1.1.7, which was first detected in the United Kingdom; B.1.351, originally found in the Republic of South Africa; and B.1.1.248, first seen in Brazil. Each variant has mutations throughout the virus, and, in particular, in the region of the virus’ spike protein that it uses to attach to and enter cells. Mutations in this spike protein region could make it less recognizable to T cells and neutralizing antibodies, which are made by the immune system’s B cells following infection or vaccination.
Although details about the exact levels and composition of antibody and T-cell responses needed to achieve immunity to SARS-CoV-2 are still unknown, scientists assume that strong and broad responses from both antibodies and T cells are required to mount an effective immune response. CD8+ T cells limit infection by recognizing parts of the virus protein presented on the surface of infected cells and killing those cells.
In their study of recovered COVID-19 patients, the researchers determined that SARS-CoV-2-specific CD8+ T-cell responses remained largely intact and could recognize virtually all mutations in the variants studied. While larger studies are needed, the researchers note that their findings suggest that the T cell response in convalescent individuals, and most likely in vaccinees, are largely not affected by the mutations found in these three variants, and should offer protection against emerging variants.
Optimal immunity to SARS-Cov-2 likely requires strong multivalent T-cell responses in addition to neutralizing antibodies and other responses to protect against current SARS-CoV-2 strains and emerging variants, the authors indicate. They stress the importance of monitoring the breadth, magnitude and durability of the anti-SARS-CoV-2 T-cell responses in recovered and vaccinated individuals as part of any assessment to determine if booster vaccinations are needed.
The WHO team is expected to soon publish a 300-page final report on its investigation, after scrapping plans for an interim report on the origins of SARS-CoV-2 — the new coronavirus responsible for killing 2.7 million people globally
Reporter: Aviva Lev-Ari, PhD, RN
UPDATED on 4/1/2021
Coronavirus: More work needed to rule out China lab leak theory says WHO
START QUOTE
The head of the World Health Organization (WHO) has said further investigation is needed to conclusively rule out that Covid-19 emerged from a laboratory in China.
Tedros Adhanom Ghebreyesus said that although a lab leak was the least likely cause, more research was needed.
The US and other countries have criticised China for failing to provide the WHO with sufficient data.
Beijing has always dismissed the allegations of a virus leak.
A report by WHO and Chinese experts released on Tuesday, said the lab leak explanation was highly unlikely and the virus had probably jumped from bats to humans via another intermediary animal.
China has yet to respond to the WHO’s latest statement.
‘All hypothesis on the table’
However the theory that the virus might have come from a leak in a laboratory “requires further investigation, potential with additional missions involving specialist experts,” Dr Tedros said on Tuesday.
“Let me say clearly that as far as WHO is concerned, all hypothesis remain on the table,” he added.
The virus was first detected in Wuhan, in China’s Hubei province in late 2019. An international team of experts travelled to to the city in January to probe the origins of the virus.
The team investigated all possibilities, including one theory that the virus had originated at the Wuhan Institute of Virology. The institute is the world’s leading authority on the collection, storage and study of bat coronaviruses.
International criticism
In response to the WHO report, the US and 13 allies including South Korea, Australia and the UK voiced concern over the findings and urged China to provide “full access” to experts.
The statement said the mission to Wuhan was “significantly delayed and lacked access to complete, original data and samples”.
“Scientific missions like these should be able to do their work under conditions that produce independent and objective recommendations and findings.”
The group pledged to work together with the WHO.
Former US President Donald Trump was among those who supported the theory that the virus might have escaped from a lab.
WHO investigation team leader, Peter Ben Embarek said on Tuesday his team had felt under political pressure, including from outside China but said he was never pressed to remove anything from the team’s final report.
He also confirmed his team had found no evidence that any laboratories in Wuhan were involved in the outbreak.
The former director of the Centers for Disease Control and Prevention believes the virus that causes COVID-19 escaped from a lab in Wuhan, China, according to a new interview.
Robert Redfield told CNN on Friday that it was his “opinion” that SARS-CoV-2 — the new coronavirus responsible for killing 2.7 million people globally — did not evolve naturally.
“I’m of the point of view that I still think the most likely etiology of this pathology in Wuhan was from a laboratory — escaped,” said Redfield, who led the CDC during the height of the pandemic. “Other people don’t believe that. That’s fine. Science will eventually figure it out.”
Researchers believe the deadly and highly transmissible strain of coronavirus behind the global pandemic mutated from a virus that infects animals — namely, bats — to one that sickens humans.
But some believe the virus was somehow released from the Wuhan Institute of Virology — which is the only lab in China authorized to study the most dangerous known pathogens, according to Axios.
“It’s not unusual for respiratory pathogens that are being worked on in a laboratory to infect the laboratory worker. … That’s not implying any intentionality,” Redfield said. “It’s my opinion, right? But I am a virologist. I have spent my life in virology.
“I do not believe this somehow came from a bat to a human and at that moment in time, that the virus came to the human, became one of the most infectious viruses that we know in humanity for human-to-human transmission.”
Redfield said usually when a virus jumps from animals to humans, “it takes a while for it to figure out how to become more and more efficient in human-to-human transmission.”
What they’re saying: “I’m of the point of view that I still think the most likely etiology of this pathology in Wuhan was from a laboratory. Escaped. Other people don’t believe that. That’s fine. Science will eventually figure it out,” Redfield told CNN’s Sanjay Gupta.
“It’s not unusual for respiratory pathogens that are being worked on in a laboratory to infect the laboratory worker. … That’s not implying any intentionality. It’s my opinion, right? But I am a virologist. I have spent my life in virology,” he continued.
“I do not believe this somehow came from a bat to a human and at that moment in time that the virus came to the human, became one of the most infectious viruses that we know in humanity for human-to-human transmission.”
Between the lines: Lab accidents in the U.S. are not especially rare, as USA Today’s Alison Young noted in a recent opinion piece arguing why the Wuhan lab theory cannot be ruled out. The CDC itself experienced a possible contamination in a lab where it was making COVID-19 test kits early in the pandemic.
What to watch: The WHO team is expected to soon publish a 300-page final report on its investigation, after scrapping plans for an interim report amid mounting tensions between the U.S. and China.
This article is part of Harvard Medical School’s continuing coverageof medicine, biomedical research, medical education and policy related to the SARS-CoV-2 pandemic and the disease COVID-19.
Harvard University and AbbVie today announced a $30 million collaborative research alliance, launching a multi-pronged effort at Harvard Medical School to study and develop therapies against emergent viral infections, with a focus on those caused by coronaviruses and by viruses that lead to hemorrhagic fever.
The collaboration aims to rapidly integrate fundamental biology into the preclinical and clinical development of new therapies for viral diseases that address a variety of therapeutic modalities. HMS has led several large-scale, coordinated research efforts launched at the beginning of the COVID-19 pandemic.
“A key element of having a strong R&D organization is collaboration with top academic institutions, like Harvard Medical School, to develop therapies for patients who need them most,” said Michael Severino, vice chairman and president of AbbVie. “There is much to learn about viral diseases and the best way to treat them. By harnessing the power of collaboration, we can develop new therapeutics sooner to ensure the world is better prepared for future potential outbreaks.”
“The cataclysmic nature of the COVID-19 pandemic reminds us how vital it is to be prepared for the next public health crisis and how critical collaboration is on every level—across disciplines, across institutions and across national boundaries,” said George Q. Daley, dean of Harvard Medical School. “Harvard Medical School, as the nucleus of an ecosystem of fundamental discovery and therapeutic translation, is uniquely positioned to propel this transformative research alongside allies like AbbVie.”
AbbVie will provide $30 million over three years and additional in-kind support leveraging AbbVie’s scientists, expertise and facilities to advance collaborative research and early-stage development efforts across five program areas that address a variety of therapeutic modalities:
Immunity and immunopathology—Study of the fundamental processes that impact the body’s critical immune responses to viruses and identification of opportunities for therapeutic intervention.
Led by Ulirich Von Andrian, the Edward Mallinckrodt Jr. Professor of Immunopathology in the Blavatnik Institute at HMS and program leader of basic immunology at the Ragon Institute of MGH, MIT and Harvard, and Jochen Salfeld, vice president of immunology and virology discovery at AbbVie.
Host targeting for antiviral therapies—Development of approaches that modulate host proteins in an effort to disrupt the life cycle of emergent viral pathogens.
Led by Pamela Silver, the Elliot T. and Onie H. Adams Professor of Biochemistry and Systems Biology in the Blavatnik Institute at HMS, and Steve Elmore, vice president of drug discovery science and technology at AbbVie.
Antibody therapeutics—Rapid development of therapeutic antibodies or biologics against emergent pathogens, including SARS-CoV-2, to a preclinical or early clinical stage.
Led by Jonathan Abraham, assistant professor of microbiology in the Blavatnik Institute at HMS, and by Jochen Salfeld, vice president of immunology and virology discovery at AbbVie.
Small molecules—Discovery and early-stage development of small-molecule drugs that would act to prevent replication of known coronaviruses and emergent pathogens.
Led by Mark Namchuk, executive director of therapeutics translation at HMS and senior lecturer on biological chemistry and molecular pharmacology in the Blavatnik Institute at HMS, and Steve Elmore, vice president of drug discovery science and technology at AbbVie.
Translational development—Preclinical validation, pharmacological testing, and optimization of leading approaches, in collaboration with Harvard-affiliated hospitals, with program leads to be determined.
This article is part of Harvard Medical School’s continuing coverage of medicine, biomedical research, medical education, and policy related to the SARS-CoV-2 pandemic and the disease COVID-19.
Less than a year ago, Harvard Medical School researchers and international colleagues unveiled a platform called VirtualFlow that could swiftly sift through more than 1 billion chemical compounds and identify those with the greatest promise to become disease-specific treatments, providing researchers with invaluable guidance before they embark on expensive and time-consuming lab experiments and clinical trials.
Propelled by the urgent needs of the pandemic, the team has now pushed VirtualFlow even further, conducting 45 screens of more than 1 billion compounds each and ranking the compounds with the greatest potential for fighting COVID-19—including some that are already approved by the FDA for other diseases.
“This was the largest virtual screening effort ever done,” said VirtualFlow co-developer Christoph Gorgulla, research fellow in biological chemistry and molecular pharmacology in the labs of Haribabu Arthanari and Gerhard Wagner in the Blavatnik Institute at HMS.
The results were published in January in the open-access journal iScience.
The team searched for compounds that bind to any of 15 proteins on SARS-CoV-2 or two human proteins, ACE2 and TMPRSS2, known to interact with the virus and enable infection.
Researchers can now explore on an interactive website the 1,000 most promising compounds from each screen and start testing in the lab any ones they choose.
The urgency of the pandemic and the sheer number of candidate compounds inspired the team to release the early results to the scientific community.
“No one group can validate all the compounds as quickly as the pandemic demands,” said Gorgulla, who is also an associate of the Department of Physics at Harvard University. “We hope that our colleagues can collectively use our results to identify potent inhibitors of SARS-CoV-2.”
In most cases, it will take years to find out whether a compound is safe and effective in humans. For some of the compounds, however, researchers have a head start.
Hundreds of the most promising compounds that VirtualFlow flagged are already FDA approved or being studied in clinical or preclinical trials for other diseases. If researchers find that one of those compounds proves effective against SARS-CoV-2 in lab experiments, the data their colleagues have already collected could save time establishing safety in humans.
Other compounds among VirtualFlow’s top hits are currently being assessed in clinical trials for COVID-19, including several drugs in the steroid family. In those cases, researchers could build on the softwarefindings to investigate how those drug candidates work at the molecular level—something that’s not always clear even when a drug works well.
It shows what we’re capable of computationally during a pandemic.
Hari Arthanari
In another effort to speed successful transitions from computer to clinic, the team has joined in Harvard’s partnership with pharmaceutical company AbbVie.
If any successful drugs eventually arise from the VirtualFlow screens, they would complement other strategies in the fight against COVID-19. For instance, drugs that halt viral replication or prevent it from entering cells could help those who cannot be vaccinated.
The nature of the screens also raises the likelihood that drugs developed against current forms of SARS-CoV-2 would work against future mutations or other coronaviruses, the authors say.
Computing power
The work was made possible in large part by about $1 million in cloud computing hours awarded by Google through a COVID-19 research grant program.
Gorgulla and colleagues used that power to screen how well the compounds bound to more than 40 sites across the 15 viral proteins as well as to the two human proteins—effectively trying 1 billion 3D puzzle pieces in 40 places each.
The team selected the sites because blocking them with compounds would either prevent SARS-CoV-2 from entering cells, prevent the virus from replicating and thus lower viral load, reduce the virus’s ability to evade or subvert our immune defenses, or disrupt viral assembly and packaging.
Many of the sites have not yet been investigated by other groups, as far as the team is aware.
“We’re exploring new avenues on how to tackle the virus. This is one of the most exciting aspects of our project,” said Gorgulla.
One benefit of studying dozens of sites on 17 proteins at once is the possibility of identifying or developing multiple drugs that, when combined, combat SARS-CoV-2 infection on different fronts. Such drug cocktails would have a better chance of halting the virus in its tracks and overcoming future mutations than a single drug that works on one protein site.
Some sites included in the screen are shared among other coronaviruses of worldwide concern. Any compound that binds to one of those sites has a “high” chance of also combating SARS, MERS, or as-yet-unknown coronavirus diseases, said Arthanari.
“We are in a position to discover pan-coronavirus drugs and help prepare for the next coronavirus pandemic, should there ever be one,” said Gorgulla.
Regardless of the outcomes, the work raises the benchmark for virtual screening and demonstrates the current power of computing in biological research.
“It shows what we’re capable of computationally during a pandemic,” said Arthanari.
The project has also brought special satisfaction to team members who don’t typically work on projects so closely tied to human health.
Scanning electron micrograph of a human T lymphocyte (also called a T cell) from the immune system of a healthy donor. NIAID
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