A Recombinant VSV-Based Bivalent Vaccine Effectively Protects against Both SARS-CoV-2 and Influenza A Virus Infection.

COVID-19 and influenza are both highly contagious respiratory diseases that have been serious threats to global public health. It is necessary to develop a bivalent vaccine to control these two infectious diseases simultaneously. In this study, we generated three attenuated replicating recombinant vesicular stomatitis virus (rVSV)-based vaccine candidates against both SARS-CoV-2 and influenza viruses. These rVSV-based vaccines coexpress SARS-CoV-2 Delta spike protein (SP) bearing the C-terminal 17 amino acid (aa) deletion (SPΔC) and I742A point mutation, or the SPΔC with a deletion of S2 domain, or the RBD domain, and a tandem repeat harboring four copies of the highly conserved influenza M2 ectodomain (M2e) that fused with the Ebola glycoprotein DC-targeting/activation domain. Animal immunization studies have shown that these rVSV bivalent vaccines induced efficient humoral and cellular immune responses against both SARS-CoV-2 SP and influenza M2 protein, including high levels of neutralizing antibodies against SARS-CoV-2 Delta and other variant SP-pseudovirus infections. Importantly, immunization of the rVSV bivalent vaccines effectively protected hamsters or mice against the challenges of SARS-CoV-2 Delta variant and lethal H1N1 and H3N2 influenza viruses and significantly reduced respiratory viral loads. Overall, this study provides convincing evidence for the high efficacy of this bivalent vaccine platform to be used and/or easily adapted to produce new vaccines against new or reemerging SARS-CoV-2 variants and influenza A virus infections. IMPORTANCE Given that both COVID-19 and influenza are preferably transmitted through respiratory droplets during the same seasons, it is highly advantageous to develop a bivalent vaccine that could simultaneously protect against both COVID-19 and influenza. In this study, we generated the attenuated replicating recombinant vesicular stomatitis virus (rVSV)-based vaccine candidates that target both spike protein of SARS-Cov-2 Delta variant and the conserved influenza M2 domain. Importantly, these vaccine candidates effectively protected hamsters or mice against the challenges of SARS-CoV-2 Delta variant and lethal H1N1 and H3N2 influenza viruses and significantly reduced respiratory viral loads.

COVID-19 severity associates with pulmonary redistribution of CD1c+ DCs and inflammatory transitional and nonclassical monocytes.

SARS-CoV-2 is responsible for the development of coronavirus disease 2019 (COVID-19) in infected individuals, who can either exhibit mild symptoms or progress toward a life-threatening acute respiratory distress syndrome (ARDS). Exacerbated inflammation and dysregulated immune responses involving T and myeloid cells occur in COVID-19 patients with severe clinical progression. However, the differential contribution of specific subsets of dendritic cells and monocytes to ARDS is still poorly understood. In addition, the role of CD8+ T cells present in the lung of COVID-19 patients and relevant for viral control has not been characterized. Here, we have studied the frequencies and activation profiles of dendritic cells and monocytes present in the blood and lung of COVID-19 patients with different clinical severity in comparison with healthy individuals. Furthermore, these subpopulations and their association with antiviral effector CD8+ T cell subsets were also characterized in lung infiltrates from critical COVID-19 patients. Our results indicate that inflammatory transitional and nonclassical monocytes and CD1c+ conventional dendritic cells preferentially migrate from blood to lungs in patients with severe COVID-19. Thus, this study increases the knowledge of specific myeloid subsets involved in the pathogenesis of COVID-19 disease and could be useful for the design of therapeutic strategies for fighting SARS-CoV-2 infection.

Comparison of the diagnostic sensitivity of SARS-CoV-2 nucleoprotein and glycoprotein-based antibody tests.

The emergence of the severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) has been followed by the rapid development of antibody tests. To assess the utility of the tests for clinical use and seroepidemiologic studies, we examined the sensitivity of commercial antibody tests from Roche, Abbott, Novatec, Virotech Siemens, Euroimmun, and Mediagnost in a prospective diagnostic study. The tests were evaluated with 73 sera from SARS CoV-2 RNA positive individuals with mild to moderate disease or asymptomatic infection. Sera were obtained at 2-3 weeks (N = 25) or > 4 weeks (N = 48) after symptom onset and viral RNA test. The overall sensitivity of the tests ranged from 64.4-93.2%. The most sensitive assays recognized 95.8-100 % of the sera obtained after 4 weeks or later. Sera drawn at 2-3 weeks were recognized with lower sensitivity indicating that the optimal time point for serologic testing is later than 3 weeks after onset of the disease. Nucleoprotein- and glycoproteinbased assays had similar sensitivity indicating that tests with both antigens are suitable for serological diagnostics. Breakdown of the test results showed that nucleoprotein- and glycoprotein-based tests of comparable sensitivity reacted with different sets of sera. The observation indicates that a combination of nucleoprotein- and glycoprotein-based tests would increase the percentage of positive results.

Vulnerabilities in coronavirus glycan shields despite extensive glycosylation.

Severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronaviruses (CoVs) are zoonotic pathogens with high fatality rates and pandemic potential. Vaccine development focuses on the principal target of the neutralizing humoral immune response, the spike (S) glycoprotein. Coronavirus S proteins are extensively glycosylated, encoding around 66-87 N-linked glycosylation sites per trimeric spike. Here, we reveal a specific area of high glycan density on MERS S that results in the formation of oligomannose-type glycan clusters, which were absent on SARS and HKU1 CoVs. We provide a comparison of the global glycan density of coronavirus spikes with other viral proteins including HIV-1 envelope, Lassa virus glycoprotein complex, and influenza hemagglutinin, where glycosylation plays a known role in shielding immunogenic epitopes. Overall, our data reveal how organisation of glycosylation across class I viral fusion proteins influence not only individual glycan compositions but also the immunological pressure across the protein surface.

Design of a Novel Multi Epitope-Based Vaccine for Pandemic Coronavirus Disease (COVID-19) by Vaccinomics and Probable Prevention Strategy against Avenging Zoonotics.

The emergence and rapid expansion of the coronavirus disease (COVID-19) require the development of effective countermeasures especially a vaccine to provide active acquired immunity against the virus. This study presented a comprehensive vaccinomics approach applied to the complete protein data published so far in the National Center for Biotechnological Information (NCBI) coronavirus data hub. We identified non-structural protein 8 (Nsp8), 3C-like proteinase, and spike glycoprotein as potential targets for immune responses to COVID-19. Epitopes prediction illustrated both B-cell and T-cell epitopes associated with the mentioned proteins. The shared B and T-cell epitopes: DRDAAMQRK and QARSEDKRA of Nsp8, EDMLNPNYEDL and EFTPFDVVR of 3C-like proteinase, and VNNSYECDIPI of the spike glycoprotein are regions of high potential interest and have a high likelihood of being recognized by the human immune system. The vaccine construct of the epitopes shows stimulation of robust primary immune responses and high level of interferon gamma. Also, the construct has the best conformation with respect to the tested innate immune receptors involving vigorous molecular mechanics and solvation energy. Designing of vaccination strategies that target immune response focusing on these conserved epitopes could generate immunity that not only provide cross protection across Betacoronaviruses but additionally resistant to virus evolution.