The Potential of Developing Pan-Coronaviral Antibodies to Spike Peptides in Convalescent COVID-19 Patients.
ABSTRACT: Coronaviruses share conservative spike protein (S) on their enveloped membrane surface, where S1 subunit recognizes and binds the cellular receptor, and the S2 subunit mediates membrane fusion. This similarity raises the question: does coronaviral infection by one create protection to others? Convalescent SARS-CoV-2 (COVID-19) sera were tested for cross reactivity with peptides from Middle East respiratory syndrome coronavirus (MERS-CoV) which shares 74% homology. Our results showed significant cross-reactivity with a peptide of the heptad repeat 2 (HR2) domain of the MERS-CoV spike protein. Sera samples of 47 validated seropositive convalescent COVID-19 patients and 40 sera samples of control patients, collected in pre-COVID time were used to establish cross-bind reactivity with the MERS-CoV peptide. Significantly stronger binding (p?
Project description:The on-going COVID-19 pandemic requires a deeper understanding of the long-term antibody responses that persist following SARS-CoV-2 infection. To that end, we determined epitope-specific IgG antibody responses in COVID-19 convalescent sera collected at 5 months post-diagnosis and compared that to sera from naïve individuals. Each serum sample was reacted with a high-density peptide microarray representing the complete proteome of SARS-CoV-2 as 15 mer peptides with 11 amino acid overlap and homologs of spike glycoprotein, nucleoprotein, membrane protein, and envelope small membrane protein from related human coronaviruses. Binding signatures were compared between COVID-19 convalescent patients and naïve individuals using the web service tool EPIphany.
Project description:ABSTRACT Pandemic SARS-CoV-2 has caused unprecedented mortalities. Vaccine is in urgent need to stop the pandemic. Despite great progresses on SARS-CoV-2 vaccine development, the efficacy of the vaccines remains to be determined. Deciphering the interactions of the viral epitopes with the elicited neutralizing antibodies in convalescent population inspires the vaccine development. In this study, we devised a peptide array composed of 20-mer overlapped peptides of spike (S), membrane (M) and envelope (E) proteins, and performed a screening with 120 COVID-19 convalescent sera and 24 non-COVID-19 sera. We identified five SARS-CoV-2-specific dominant epitopes that reacted with above 40% COVID-19 convalescent sera. Of note, two peptides non-specifically interacted with most of the non-COVID-19 sera. Neutralization assay indicated that only five sera completely blocked viral infection at the dilution of 1:200. By using a peptide-compete neutralizing assay, we found that three dominant epitopes partially competed the neutralization activity of several convalescent sera, suggesting antibodies elicited by these epitopes played an important role in neutralizing viral infection. The epitopes we identified in this study may serve as vaccine candidates to elicit neutralizing antibodies in most vaccinated people or specific antigens for SARS-CoV-2 diagnosis.
Project description:With the development of the COVID-19 epidemic, there is an urgent need to establish a system for determining the effectiveness and neutralizing activity of vaccine candidates in biosafety level 2 (BSL-2) facilities. Previously, researchers had developed a pseudotyped virus system for SARS-CoV and MERS-CoV, based on HIV-1 core, bearing virus spike protein. During the development of a pseudotyped SARS-CoV-2 system, a eukaryotic expression plasmid expressing SARS-CoV-2 spike (S) protein was constructed and then co-transfected with HIV-1 based plasmid which containing the firefly luciferase reporter gene, into HEK293T cells to prepare the pseudotyped SARS-CoV-2 virus (ppSARS-2). We have successfully established the pseudotyped SARS-CoV-2 system for neutralization and entry inhibition assays. Huh7.5 cell line was found to be the most susceptible to our pseudotyped virus model. Different levels of neutralizing antibodies were detected in convalescent serum samples of COVID-19 patients using ppSARS-2. The recombinant, soluble, angiotensin-converting enzyme 2 protein was found to inhibit the entry of ppSARS-2 in Huh7.5 cells effectively. Furthermore, the neutralization results for ppSARS-2 were consistent with those of live SARS-CoV-2 and determined using the serum samples from convalescent patients. In conclusion, we have developed an easily accessible and reliable tool for studying the neutralizing efficiency of antibodies against SARS-CoV-2 and the entry process of the virus in a BSL-2 laboratory.
Project description:We present a comprehensive vaccine strategy for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by combining antigen optimization and nanoparticle display. We first developed a receptor binding domain (RBD)-specific antibody column for purification and displayed the RBD on self-assembling protein nanoparticles (SApNPs) using the SpyTag/SpyCatcher system. We then identified the heptad repeat 2 (HR2) stalk as a major cause of spike metastability, designed an HR2-deleted glycine-capped spike (S2G?HR2), and displayed S2G?HR2 on three SApNPs with high yield, purity, and antigenicity. Compared to the RBD, the RBD-ferritin SApNP elicited a more potent murine neutralizing antibody (NAb) response on par with the spike. S2G?HR2 elicited two-fold-higher NAb titers than the proline-capped spike (S2P), while S2G?HR2 SApNPs derived from multilayered E2p and I3-01v9 60-mers elicited up to 10-fold higher NAb titers. The S2G?HR2-presenting I3-01v9 SApNP also induced critically needed T-cell immunity, thereby providing a next-generation vaccine candidate to battle the COVID-19 pandemic. ONE-SENTENCE SUMMARY:The receptor binding domain and stabilized SARS-CoV-2 spike were displayed on nanoparticles as vaccine antigens and elicited potent immune responses.
Project description:There is an urgent need for vaccines and therapeutics to prevent and treat COVID-19. Rapid SARS-CoV-2 countermeasure development is contingent on the availability of robust, scalable, and readily deployable surrogate viral assays to screen antiviral humoral responses, define correlates of immune protection, and down-select candidate antivirals. Here, we generate a highly infectious recombinant vesicular stomatitis virus (VSV) bearing the SARS-CoV-2 spike glycoprotein S as its sole entry glycoprotein and show that this recombinant virus, rVSV-SARS-CoV-2 S, closely resembles SARS-CoV-2 in its entry-related properties. The neutralizing activities of a large panel of COVID-19 convalescent sera can be assessed in a high-throughput fluorescent reporter assay with rVSV-SARS-CoV-2 S, and neutralization of rVSV-SARS-CoV-2 S and authentic SARS-CoV-2 by spike-specific antibodies in these antisera is highly correlated. Our findings underscore the utility of rVSV-SARS-CoV-2 S for the development of spike-specific therapeutics and for mechanistic studies of viral entry and its inhibition.
Project description:Neutralizing antibodies targeting the receptor-binding domain (RBD) of the SARS-CoV-2 spike (S) block severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into cells via surface-expressed angiotensin-converting enzyme 2 (ACE2). We used a surrogate virus neutralization test (sVNT) and SARS-CoV-2 S protein-pseudotyped vesicular stomatitis virus (VSV) vector-based neutralization assay (pVNT) to assess the degree to which serum antibodies from coronavirus disease 2019 (COVID-19) convalescent patients interfere with the binding of SARS-CoV-2 S to ACE2. Both tests revealed neutralizing anti-SARS-CoV-2 S antibodies in the sera of ~90% of mildly and 100% of severely affected COVID-19 convalescent patients. Importantly, sVNT and pVNT results correlated strongly with each other and to the levels of anti-SARS-CoV-2 S1 IgG and IgA antibodies. Moreover, levels of neutralizing antibodies correlated with the duration and severity of clinical symptoms but not with patient age. Compared to pVNT, sVNT is less sophisticated and does not require any biosafety labs. Since this assay is also much faster and cheaper, sVNT will not only be important for evaluating the prevalence of neutralizing antibodies in a population but also for identifying promising plasma donors for successful passive antibody therapy.
Project description:There is an urgent need for vaccines and therapeutics to prevent and treat COVID-19. Rapid SARS-CoV-2 countermeasure development is contingent on the availability of robust, scalable, and readily deployable surrogate viral assays to screen antiviral humoral responses, and define correlates of immune protection, and to down-select candidate antivirals. Here, we describe a highly infectious recombinant vesicular stomatitis virus bearing the SARS-CoV-2 spike glycoprotein S as its sole entry glycoprotein that closely resembles the authentic agent in its entry-related properties. We show that the neutralizing activities of a large panel of COVID-19 convalescent sera can be assessed in high-throughput fluorescent reporter assay with rVSV-SARS-CoV-2 S and that neutralization of the rVSV and authentic SARS-CoV-2 by spike-specific antibodies in these antisera is highly correlated. Our findings underscore the utility of rVSV-SARS-CoV-2 S for the development of spike-specific vaccines and therapeutics and for mechanistic studies of viral entry and its inhibition.
Project description:Replication-competent vesicular stomatitis virus (VSV)-based recombinant viruses are useful tools for studying emerging and highly pathogenic enveloped viruses in level 2 biosafety facilities. Here, we used a replication-competent recombinant VSVs (rVSVs) encoding the spike (S) protein of SARS-CoV-2 in place of the original G glycoprotein (rVSV-eGFP-SARS-CoV-2) to develop a high-throughput entry assay for SARS-CoV-2. The S protein was incorporated into the recovered rVSV-eGFP-SARS-CoV-2 particles, which could be neutralized by sera from convalescent COVID-19 patients. The recombinant SARS-CoV-2 also displayed entry characteristics similar to the wild type virus, such as cell tropism and pH-dependence. The neutralizing titers of antibodies and sera measured by rVSV-eGFP-SARS-CoV-2 were highly correlated with those measured by wild-type viruses or pseudoviruses. Therefore, this is a safe and convenient screening tool for SARS-CoV-2, and it may promote the development of COVID-19 vaccines and therapeutics.
Project description:The current practice for diagnosis of COVID-19, based on SARS-CoV-2 PCR testing of pharyngeal or respiratory specimens in a symptomatic patient at high epidemiologic risk, likely underestimates the true prevalence of infection. Serologic methods can more accurately estimate the disease burden by detecting infections missed by the limited testing performed to date. Here, we describe the validation of a coronavirus antigen microarray containing immunologically significant antigens from SARS-CoV-2, in addition to SARS-CoV, MERS-CoV, common human coronavirus strains, and other common respiratory viruses. A comparison of antibody profiles detected on the array from control sera collected prior to the SARS-CoV-2 pandemic versus convalescent blood specimens from virologically confirmed COVID-19 cases demonstrates near complete discrimination of these two groups, with improved performance from use of antigen combinations that include both spike protein and nucleoprotein. This array can be used as a diagnostic tool, as an epidemiologic tool to more accurately estimate the disease burden of COVID-19, and as a research tool to correlate antibody responses with clinical outcomes.
Project description:The need for proven disease-specific treatments for the novel pandemic coronavirus SARS-CoV-2 necessitates a worldwide search for therapeutic options. Since the SARS-CoV-2 virus shares extensive homology with SARS-CoV and MERS-CoV, effective therapies for SARS-CoV and MERS-CoV may also have therapeutic potential for the current COVID-19 outbreak. To identify therapeutics that might be repositioned for treatment of the SARS-CoV-2 disease COVID-19, we strategically reviewed the literature to identify existing therapeutics with evidence of efficacy for the treatment of the three coronaviruses that cause severe respiratory illness (SARS-CoV, MERS-CoV, and SARS-CoV-2). Mechanistic and in vitro analyses suggest multiple promising therapeutic options with potential for repurposing to treat patients with COVID-19. Therapeutics with particularly high potential efficacy for repurposing include camostat mesylate, remdesivir, favipiravir, tocilizumab, baricitinib, convalescent plasma, and humanized monoclonal antibodies. Camostat mesylate has shown therapeutic potential, likely by preventing viral entry into epithelial cells. In early research, the targeted antivirals remdesivir and favipiravir appear to benefit patients by decreasing viral replication; clinical trials suggest that remdesivir speeds recovery from COVID-19. Tocilizumab and baricitinib appear to improve mortality by preventing a severe cytokine storm. Convalescent plasma and humanized monoclonal antibodies offer passive immunity and decreased recovery time. This review highlights potential therapeutic options that may be repurposed to treat COVID-19 and suggests opportunities for further research.