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.
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® (siR‐7‐EM/KK‐46) 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 siR‐7‐EM/KK‐46 (3.7 mg and 11.1 mg/day: low and high dose, respectively) in comparison with standard etiotropic drug treatment (control group) in patients hospitalized with moderate COVID‐19 (N = 52 for each group). The primary endpoint was the time to clinical improvement according to predefined criteria within 14 days of randomization. Results Patients from the low‐dose group achieved the primary endpoint defined by simultaneous achievement of relief of fever, normalization of respiratory rate, reduction of coughing, and oxygen saturation of >95% for 48 h significantly earlier (median 6 days; 95% confidence interval [CI]: 5–7, HR 1.75, p = .0005) than patients from the control group (8 days; 95% CI: 7–10). No significant clinical efficacy was observed for the high‐dose group. Adverse events were reported in 26 (50.00%), 25 (48.08%), and 28 (53.85%) patients from the low‐, high‐dose and control group, respectively. None of them were associated with siR‐7‐EM/KK‐46. Conclusions siR‐7‐EM/KK‐46, a SARS‐CoV‐2‐specific siRNA‐peptide dendrimer formulation is safe, well tolerated and significantly reduces time to clinical improvement in patients hospitalized with moderate COVID‐19 compared to standard therapy in a randomized controlled trial.
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 >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.
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