Generation of a virus-like particles based vaccine against IgE.

BACKGROUND: Anti-IgE immunotherapy with monoclonal antibodies represents a breakthrough in treatment of severe allergic diseases. However, drawbacks such as short half-life and high price are not negligible. Our objective is to develop an anti-IgE vaccine based on virus-like particles (VLPs) which can induce long-lasting neutralizing IgG anti-IgE antibodies reducing allergic responses without causing intrinsic mast cell activation due to IgE cross-linking. METHODS: The vaccines were made by chemically coupling three synthetic mouse IgE-Fc fragments to plant-derived immunologically optimized CuMVTT VLPs. The immunogenicity of the vaccines was tested by immunizing naive or allergic mice either with the coupled vaccines or the VLP control followed by systemic or local allergen challenge. RESULTS: Mice immunized with the vaccines exhibited high titers of anti-IgE antibodies in the sera and high levels of anti-IgE secreting plasma cells in lymphoid organs. Moreover, free IgE in serum were reduced by the induced anti-IgE antibodies; therefore, less IgE was bound to FcεRI on the surface of basophils. In line with these reduced IgE levels on effector cells after vaccination, immunized mice were protected from challenge with allergens. Importantly, despite presence of anti-IgE antibodies, no signs of acute or chronic allergic response were seen in immunized allergic mice. CONCLUSION: The generated vaccines can effectively induce anti-IgE antibodies that did not cause allergic responses in sensitized mice but were able to decrease the level of free and cell bound IgE and protected sensitized animals from allergic responses upon allergen challenge.

IgE glycans promote anti-IgE IgG autoantibodies that facilitate IgE serum clearance via Fc Receptors.

Background: Recent studies have shown that IgE glycosylation significantly impacts the ability of IgE to bind to its high-affinity receptor FcεRI and exert effector functions. We have recently demonstrated that immunizing mice with IgE in a complex with an allergen leads to a protective, glycan-dependent anti-IgE response. However, to what extent the glycans on IgE determine the induction of those antibodies and how they facilitate serum clearance is unclear.Therefore, we investigated the role of glycan-specific anti-IgE IgG autoantibodies in regulating serum IgE levels and preventing systemic anaphylaxis by passive immunization. Methods: Mice were immunized using glycosylated or deglycosylated IgE-allergen-immune complexes (ICs) to induce anti-IgE IgG antibodies. The anti-IgE IgG antibodies were purified and used for passive immunization. Results: Glycosylated IgE-ICs induced a significantly higher anti-IgE IgG response and more IgG-secreting plasma cells than deglycosylated IgE-ICs. Passive immunization of IgE-sensitized mice with purified anti-IgE IgG increased the clearance of IgE and prevented systemic anaphylaxis upon allergen challenge. Anti-IgE IgG purified from the serum of mice immunized with deglycosylated IgE-ICs, led to a significantly reduced elimination and protection, confirming that the IgE glycans themselves are the primary drivers of the protectivity induced by the IgE-immune complexes. Conclusion: IgE glycosylation is essential for a robust anti-IgE IgG response and might be an important regulator of serum IgE levels.

A scalable and highly immunogenic virus-like particle-based vaccine against SARS-CoV-2.

BACKGROUND: SARS-CoV-2 caused one of the most devastating pandemics in the recent history of mankind. Due to various countermeasures, including lock-downs, wearing masks, and increased hygiene, the virus has been controlled in some parts of the world. More recently, the availability of vaccines, based on RNA or adenoviruses, has greatly added to our ability to keep the virus at bay; again, however, in some parts of the world only. While available vaccines are effective, it would be desirable to also have more classical vaccines at hand for the future. Key feature of vaccines for long-term control of SARS-CoV-2 would be inexpensive production at large scale, ability to make multiple booster injections, and long-term stability at 4℃. METHODS: Here, we describe such a vaccine candidate, consisting of the SARS-CoV-2 receptor-binding motif (RBM) grafted genetically onto the surface of the immunologically optimized cucumber mosaic virus, called CuMVTT -RBM. RESULTS: Using bacterial fermentation and continuous flow centrifugation for purification, the yield of the production process is estimated to be >2.5 million doses per 1000-litre fermenter run. We demonstrate that the candidate vaccine is highly immunogenic in mice and rabbits and induces more high avidity antibodies compared to convalescent human sera. The induced antibodies are more cross-reactive to mutant RBDs of variants of concern (VoC). Furthermore, antibody responses are neutralizing and long-lived. In addition, the vaccine candidate was stable for at least 14 months at 4℃. CONCLUSION: Thus, the here presented VLP-based vaccine may be a good candidate for use as conventional vaccine in the long term.

A Novel Double Mosaic Virus-like Particle-Based Vaccine against SARS-CoV-2 Incorporates Both Receptor Binding Motif (RBM) and Fusion Domain.

COVID-19 has emerged, and has rapidly become a major health problem worldwide, causing millions of mortalities. Vaccination against COVID-19 is the most efficient way to stop the pandemic. The goal of vaccines is to induce neutralizing antibodies against SARS-CoV-2 virus. Here, we present a novel double mosaic virus-like particle (VLP) displaying two independent neutralizing epitopes, namely the receptor binding motif (RBM) located in S1 and the fusion peptide (AA 817-855) located in S2. CuMVTT virus-like particles were used as VLP scaffold and both domains were genetically fused in the middle of CuMVTT subunits, which co-assembled into double mosaic particles (CuMVTT-DF). A single fusion mosaic particle (CuMVTT-FP) containing the fusion peptide only was used for comparison. The vaccines were produced in E. coli, and electron microscopy and dynamic light scattering confirmed their integrity and homogeneity. In addition, the CuMVTT-DF vaccine was well recognized by ACE2 receptor, indicating that the RBM was in native conformation. Both CuMVTT-FP and CuMVTT-DF vaccines induced high levels of high avidity IgG antibodies as well as IgA recognizing spike and RBD in the case of CuMVTT-DF. Both vaccine candidates induced virus-neutralizing antibodies indicating that the fusion peptide can independently induce virus-neutralizing antibodies. In contrast, CuMVTT-DF containing both RBM and fusion peptide induced a higher level of neutralizing antibodies suggesting that the new double mosaic vaccine candidate CuMVTT-DF consisting of two antigens in one VLP maybe an attractive candidate for scale-up in a bacterial fermentation process for clinical development.

Neutralization of MERS 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 vaccine platforms 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 scalable, we genetically fused the receptor-binding motif (RBM) of MERS-CoV spike protein into the surface of cucumber-mosaic virus VLPs. 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 candidate (mCuMVTT-MERS) is a mosaic particle and consists of unmodified wild type monomers and genetically modified monomers displaying RBM, co-assembling within E. coli upon expression. mCuMVTT-MERS vaccine is self-adjuvanted with ssRNA, a TLR7/8 ligand which is spontaneously packaged during the bacterial expression process. The developed vaccine candidate induced high anti-RBD and anti-spike antibodies in a murine model, showing high binding avidity and an ability to completely neutralize MERS-CoV/EMC/2012 isolate, demonstrating the protective potential of the vaccine candidate for dromedaries and humans.

Antimicrobial Resistant Pattern and Capsular Typing of Streptococcus Pneumoniae Isolated from Children in Sistan -Baluchestan.

BACKGROUND: Ankyloglossia is an anatomic developmental anomaly determining by thick and short, fi brotic ferenum. Tongue changes have severe eff ects on occlusion and oropharyngeal structures. The aim of this study was to evaluate the position of hyoid in children 7-11 years` old with ankyloglossia in lateral cephalometric radiographs. MATERIALS AND METHOD: In this study 260 nasopharyngeal swabs were taken from non-vaccinated healthy children between 6 months to 6 years old at medical centers in Sistan-Baluchestan during August 2013 to January 2014. These samples were cultured on blood agar. Primary identifi cation of bacterial isolated was determined by biochemical analysis and molecular tests. Capsular typing was performed by Multiplex PCR using primers targeting cps locus that is highly conserved among diff erent capsular types. The master mixes for PCR were grouped them into six multiplex reactions. RESULTS: Out of 260 nasopharyngeal swabs, 42 isolates of Streptococcus pneumoniae were detected and identifi ed. The overall pneumococcal carriage rate was 16.1%. The most frequently isolated capsular types were: 6A/B, 19A, 19F and 23F. These capsular types accounted for 49.9% of all strains detected. CONCLUSION: We found that the prevalence of pneumococcal carriage among non-vaccinated children under six years old is about 16%. Our study provides much data about carriage rate and pneumococcal capsular types in preschool children, which is necessary for predicting the diff erent valent pneumococcal conjugated vaccines in Iran.