Intranasal administration of a VLP-based vaccine induces neutralizing antibodies against SARS-CoV-2 and variants of concern

Background: The highly contagious SARS-CoV-2 is mainly transmitted by respiratory droplets and aerosols. Consequently, people are required to wear masks and maintain a social distance to avoid spreading of the virus. Despite the success of the commercially available vaccines, the virus is still uncontained globally. Given the tropism of SARS-CoV-2, a mucosal immune reaction would help to reduce viral shedding and transmission locally. Only seven out of hundreds of ongoing clinical trials are testing the intranasal delivery of a vaccine against COVID-19. Methods: In the current study, we evaluated the immunogenicity of a traditional vaccine platform based on virus-like particles (VLPs) displaying RBD of SARS-CoV-2 for intranasal administration in a murine model. The candidate vaccine platform, CuMVTT -RBD, has been optimized to incorporate a universal T helper cell epitope derived from tetanus-toxin and is self-adjuvanted with TLR7/8 ligands. Results: CuMVTT-RBD vaccine elicited a strong systemic RBD- and spike- IgG and IgA antibodies of high avidity. Local immune response was assessed and our results demonstrate a strong mucosal antibody and plasma cell production in lung tissue. Furthermore, the induced systemic antibodies could efficiently recognize and neutralize different variants of concern (VOCs) of mutated SARS-CoV-2 RBDs. Conclusion: Our data demonstrate that intranasal administration of CuMVTT-RBD induces a protective systemic and local specific antibody response against SARS-CoV-2 and its VOCs.

Nanoparticles: Efficient, safe and affordable platforms for developing vaccines against coronaviruses

Introduction: Vaccines need to be rationally designed to be delivered to the immune system for maximizing induction of dynamic immune responses. Virus-like nanoparticles (VLPs) are ideal platforms for such 3D vaccines. Coronaviruses have recently gained a lot of attention, due to the ongoing pandemic caused by SARS-CoV-2 and previous endemics by MERS-CoV. Methods: We have provided proof of concepts in murine models for effective development of VLP-based vaccines against MERS-CoV and SASR-CoV-2. We have used chemical conjugation or genetic fusion techniques to display receptor-binding domain or motif on our immunologically optimized (CuMVTT -VLPs). These VLPs incorporate a tetanus toxin epitope and ssRNA, TLR7/8 ligands. The vaccines were tested in murine models. Results: The vaccines are stable for more than a year at 4°C and highly scalable. Vaccination using subcutaneous or intranasal routes are feasible with nanoparticles. We demonstrated that these vaccines are highly immunogenic in mice as well as rabbits and can induce high avidity antibodies compared to convalescent human sera. Furthermore, the induced antibodies are cross-reactive with different VoCs (in case of SARS-CoV-2). The longevity of the induced immune response lasted longer than 120 days. Conclusion: Collectively, we show that VLP-based vaccines can efficiently induce high specific anti-RBD and spike antibodies that effectively neutralize different Coronaviruses and their VoCs. As Coronaviruses represent a continuous global threat to human health, it seems rational to further develop these vaccines.

Neutralization of Middle East Respiratory Syndrome coronavirus through a scalable nanoparticle vaccine

MERS-CoV continues to cause human outbreaks, so far in 27 countries worldwide following the first registered epidemic in Saudi Arabia in 2012. In this study, we produced a nanovaccine based on virus-like particles (VLPs). VLPs are safe as they lack any replication-competent genetic material, and are used since many years against hepatitis B virus (HBV), hepatitis E virus (HEV) and human papilloma virus (HPV). In order to produce a vaccine that is readily upscalable, we genetically fused the receptor-binding motif (RBM) of MERS-CoV Spike protein into cucumber- mosaic virus-like particles. The employed CuMVTT-VLPs represent a new immunologically optimized vaccine platform incorporating a universal T cell epitope derived from tetanus toxin (TT). The resultant vaccine (mCuMVTT-MERS) consists of unmodified wild type monomers and genetically modified monomers displaying RBM, both co-assemble in a prokaryotic expression system. mCuMVTT-MERS vaccine is self-adjuvanted with ssRNA, a TLR7/8 ligand which is spontaneously packaged during the expression process in E. coli. The ability of the engineered vaccine to bind to MERS-CoV receptor DPP4 was tested in a competitive ELISA. To test the safety and immunogenicity of mCuMVTT-MERS Balb/cOlaHsd mice were primed with 100ug VLPs and boosted on day 28. The developed vaccine induced high anti-RBD and anti-Spike antibodies in a murine model, showing high binding avidity and the ability to completely neutralize MERS-CoV/EMC/2012 isolate, demonstrating the protective potential of the vaccine candidate in dromedaries and humans.

Impact of decreasing respiratory rate while tolerating moderate hypercapnia on lung injury markers in patients with COVID-19 related acute respiratory distress syndrome

Rationale: Acute respiratory distress syndrome (ARDS) secondary to SARS-CoV-2 pneumonia is associated with a high mortality rate. Protective ventilation strategies, by decreasing ventilator induced lung injury (VILI), have reduced mortality in patients with ARDS. However, the role of respiratory rate (RR), a central determinant of the energy applied to the lung parenchyma remains uncertain. Objective: To evaluate the role of respiratory rate on systemic pro-inflammatory mediators, as markers of VILI, in patients with Covid-19-associated ARDS (CARDS) Methods: Prospective, randomized crossover trial in patients with CARDS, PaO2:FIO2 ratio less than 200 mmHg, and requiring deep sedation and neuromuscular blockade. All patients were ventilated with a tidal volume of 6 ml/kg IBW, and PEEP and FiO2 according to the ARDSNet table. If PaO2:FIO2 ratio was less than 150 mmHg, patients were positioned in the prone position.Two 12 hours periods with a low RR and a high RR, randomly selected, was conducted. Low RR and high RR periods were set to obtain an 8-10 breaths/min difference between groups while maintaining pH and PaCO2 within recommended limits. I:E ratio was held constant during the study.Hemodynamic and respiratory mechanics were registered, and arterial blood samples drawn for gas exchange and quantification of inflammatory biomarkers at baseline and repeated at 12 and 24 hours. Results: We enrolled 11 patients (10 males, median age 54 [51-66] years, PaO2:FIO2 108 [86-132]), and all of them were in prone position. The low RR (20 [16-23]) vs the high RR (28 [26-32]) was associated with a significantly lower energy applied to the lung (16 [12-19] vs 23 [20-32] J / min, respectively). PaCO2 and pH were kept within the recommended limits (pH 7.30 [7.25-7.35] vs 7.46 [7.43-7.50];PaCO2 48 (45-63) vs 36 (32-38) mmHg for low and high RR, respectively). There were no significant changes in any of the respiratory mechanics parameters.The change in RR did not induce differences in any inflammatory marker (IL-6, IL-8, TNF-R1) or in the markers of epithelial (receptor for advanced glycation end products, s-RAGE;Surfactant protein D, SP-D), endothelial damage (Angiopoietin-2) or the marker of profibrotic activity (transforming growth factor β, TGF-β) (table 1). Conclusion: These preliminary results reveal that a decrease in respiratory rate, tolerating moderate hypercapnia, does not modify the biomarkers of lung damage compared to a strategy of high respiratory rate in patients with CARDS.

Development of a Vaccine against SARS-CoV-2 Based on the Receptor-Binding Domain Displayed on Virus-Like Particles

The ongoing coronavirus disease (COVID-19) pandemic is caused by a new coronavirus (severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2)) first reported in Wuhan City, China. From there, it has been rapidly spreading to many cities inside and outside China. Nowadays, more than 110 million cases with deaths surpassing 2 million have been recorded worldwide, thus representing a major health and economic issues. Rapid development of a protective vaccine against COVID-19 is therefore of paramount importance. Here, we demonstrated that the recombinantly expressed receptor-binding domain (RBD) of the spike protein can be coupled to immunologically optimized virus-like particles derived from cucumber mosaic virus (CuMV_TT). The RBD displayed CuMV_TT bound to ACE2, the viral receptor, demonstrating proper folding of RBD. Furthermore, a highly repetitive display of the RBD on CuMV_TT resulted in a vaccine candidate that induced high levels of specific antibodies in mice, which were able to block binding of the spike protein to ACE2 and potently neutralize SARS-CoV-2 virus in vitro.

AP205 VLPs Based on Dimerized Capsid Proteins Accommodate RBM Domain of SARS-CoV-2 and Serve as an Attractive Vaccine Candidate

COVID-19 is a novel disease caused by SARS-CoV-2 which has conquered the world rapidly resulting in a pandemic that massively impacts our health, social activities, and economy. It is likely that vaccination is the only way to form "herd immunity" and restore the world to normal. Here we developed a vaccine candidate for COVID-19 based on the virus-like particle AP205 displaying the spike receptor binding motif (RBM), which is the major target of neutralizing antibodies in convalescent patients. To this end, we genetically fused the RBM domain of SARS-CoV-2 to the C terminus of AP205 of dimerized capsid proteins. The fused VLPs were expressed in E. coli, which resulted in insoluble aggregates. These aggregates were denatured in 8 M urea followed by refolding, which reconstituted VLP formation as confirmed by electron microscopy analysis. Importantly, immunized mice were able to generate high levels of IgG antibodies recognizing eukaryotically expressed receptor binding domain (RBD) as well as spike protein of SARS-CoV-2. Furthermore, induced antibodies were able to neutralize SARS-CoV-2/ABS/NL20. Additionally, this vaccine candidate has the potential to be produced at large scale for immunization programs.

[Responsibilities of Weaning Centers during the COVID-19 Pandemic Outbreak - Recommendations for the Assignment of ICU Capacities in COVID-19 Patients as shown by the Berlin-Brandenburg POST-SAVE-Model]. / Aufgaben der Weaning-Zentren im Pandemiefall COVID-19.

The enormous increase in patients with severe respiratory distress due to the COVID-19 pandemic outbreak requires a systematic approach to optimize ventilated patient at risk flow. A standardised algorithm called "SAVE" was developed to distribute patients with COVID-19 respiratory distress syndrome requiring invasive ventilation. This program is established by now in Berlin. An instrumental bottleneck of this approach is the vacant slot assignment in the intensive care unit to guarantee constant patient flow. The transfer of the patients after acute care treatment is needed urgently to facilitate the weaning process. In a next step we developed a triage algorithm to identify patients at SAVE intensive care units with potential to wean and transfer to weaning institutions - we called POST SAVE. This manuscript highlights the algorithms including the use of a standardised digital evaluation tool, the use of trained navigators to facilitate the communication between SAVE intensive care units and weaning institutions and the establishment of a prospective data registry for patient assignment and reevaluation of the weaning potential in the future.