Background: Respiratory birch pollen allergy and associated oral allergy syndrome affect more than 150 million people. IgE cross-sensitization to major birch pollen allergen Bet v 1 and pathogenesis-related (PR10) plant food allergens is responsible for the pollen-food allergy syndrome. Methods: We designed a recombinant protein, AB-PreS, consisting of non-allergenic peptides derived from the IgE binding sites of Bet v 1 and the cross-reactive apple allergen, Mal d 1, fused to the PreS domain of HBV surface protein as immunological carrier. AB-PreS was expressed in E. coli and purified by chromatography. The allergenic activity of AB-PreS was tested using sera and basophils from birch pollen patients allergic. The protective effect of AB-PreS was assessed by inhibition ELISA test using sera allergic patients and from immunized rabbits. Results: IgE-binding experiments and basophil activation test revealed the hypoallergenic nature of AB-PreS. IgG antibodies induced by 5 injections with AB-PreS inhibited allergic patients’ IgE binding to Bet v 1 and Mal d 1 better than did IgG induced by up to 30 injections of six licensed birch pollen allergen extract-based vaccines. Additionally, immunization with AB-PreS induced HBV-specific antibodies potentially protecting the infection. Conclusion: The recombinant AB-PreS-based vaccine is hypoallergenic, safe and superior to currently registered allergen extract-based vaccines for the treatment of the birch pollen food allergy syndrome.

Background The vast majority of SARS-CoV-2 vaccines which are licensed or under development focus on the spike (S) protein and its receptor binding domain (RBD). However, S and RBD from SARS-CoV-2 variants of concerns show considerable sequence variations and repeated injections for boosting specific immunity are necessary. Aim of this study was to develop and characterize a SARS-CoV-2 vaccine targeting the highly conserved nucleocapsid (N) protein. Methods Recombinant N protein was expressed in Escherichia coli, purified to homogeneity by chromatography and characterized by SDS-PAGE, immunoblotting, mass spectrometry, dynamic light scattering and differential scanning calorimetry. The N protein vaccine was obtained by formulation of recombinant N as squalane-based emulsion and used to immunize Balb/c mice, NOD scid gamma (NSG) mice engrafted with human PBMC, rabbits and marmoset monkeys to study safety as well as antibody and cellular immunity using ELISA for antibodies, measurement of N-specific Th1 and Th2 cytokine secretion and carboxyfluorescein succinimidyl ester (CFSE) dilution assays for CD4 + and CD8 + T cell responses. The protective effect of the vaccine was studied in SARS-CoV-2-infected Syrian hamsters. Results Immunization of mice, rabbits and Syrian hamsters with the recombinant N protein-based vaccine formulated as squalane-based emulsion (Convacell®) induced sustainable N-specific IgG responses and a N-specific mixed Th1/Th2 cytokine response. In marmoset monkeys a N-specific CD4 + as well as CD8 + T cell response was observed. Vaccinated and then infected Syrian hamsters showed reduced lung histopathology, reduced virus was detected in lung tissue, lung weight relative to the body was not increased after challenge and body weight was regained faster than in non-vaccinated animals. Repeated dose toxicity studies in mice and rabbits showed that Convacell® was well tolerated and safe. Conclusions Convacell® induced a SARS-CoV-2-specific protective immune response in Syrian hamsters. It is a new vaccine targeting the nucleocapsid protein of SARS-CoV-2 and thus may augment the armamentarium of vaccines for COVID-19.Now published:  Vaccines 2023, 11(4), 874; https://doi.org/10.3390/vaccines11040874

BACKGROUND Severe acute respiratory syndrome corona virus (SARS-CoV-2) infection frequently causes severe and prolonged disease but only few specific treatments are available. We aimed to investigate safety and efficacy of a SARS-CoV-2-specific siRNA-peptide dendrimer formulation (MIR 19 ®) targeting a conserved sequence in known SARS-CoV-2 variants for treatment of COVID-19. METHODS We conducted an open-label, randomized controlled multicenter phase II trial (NCT05184127) evaluating safety and efficacy of inhaled MIR 19 ® (3.7mg and 11.1 mg/day: groups 1 and 2, respectively) in comparison with standard etiotropic drug treatment (group 3) in patients hospitalized with moderate COVID-19. The primary endpoint was the time to clinical improvement according to predefined criteria within 14 days of randomization. RESULTS Patients from group1 had a significantly reduced (median 6 days (95% confidence interval [CI]: 5-7, HR 1.75, P=0.0005) time to clinical improvement compared to patients from group 3 (8 days (95% CI: 7-10). Normalized oxygen saturation (SpO 2>94%) occurred quicker in the group 1 (median 5 days (95% CI: 4–5, HR 1.59, P=0.0033) than in the group 3 (6 days, 95% CI: 5–8). Treatment with MIR 19® was well tolerated and safe. CONCLUSIONS MIR 19 ®, a SARS-CoV-2-specific siRNA-peptide dendrimer formulation is safe and significantly reduces time to clinical improvement in hospitalized moderate COVID-19 patients compared to standard therapy in a randomized controlled trial. MIR 19 ® treatment targets a sequence which is identical in all SARS-CoV-2 variants known so far and hence should be applicable for all of them.

Allergic sensitization without detectable specific serum IgE

Background. First vaccines for prevention of Coronavirus disease 2019 (COVID-19) are becoming available but there is a huge and unmet need for specific forms of treatment. In this study we aimed to evaluate the potent anti-SARS-CoV-2 effect of siRNA both in vitro and in vivo. Methods. To identify most effective molecule out of a panel of 15 in silico designed siRNAs, an in vitro screening system based on vectors expressing SARS-CoV-2 genes fused with the firefly luciferase reporter gene and SARS-CoV-2-infected cells was used. The most potent siRNA, siR-7, was modified by Locked nucleic acids (LNAs) to obtain siR-7-EM with increased stability and was formulated with the peptide dendrimer KK-46 for enhancing cellular uptake to allow topical application by inhalation of the final formulation - siR-7-EM/KK-46. Using the Syrian Hamster model for SARS-CoV-2 infection the antiviral capacity of siR-7-EM/KK-46 complex was evaluated. Results. We identified the siRNA, siR-7, targeting SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) as the most efficient siRNA inhibiting viral replication in vitro. Moreover, we have shown that LNA-modification and complexation with the designed peptide dendrimer enhanced the antiviral capacity of siR-7 in vitro. We demonstrated significant reduction of virus titer and total lung inflammation in the animals exposed by inhalation of siR-7-EM/KK-46 in vivo. Conclusions. Thus, we developed a therapeutic strategy for COVID-19 based on inhalation of a modified siRNA-peptide dendrimer formulation.