Background A heterologous recombinant adenovirus (rAd)-based vaccine, Gam-COVID-Vac (Sputnik V), showed a good safety profile and induced strong humoral and cellular immune responses in participants in phase 1/2 clinical trials. Here, we report preliminary results on the efficacy and safety of Gam-COVID-Vac from the interim analysis of this phase 3 trial. Methods We did a randomised, double-blind, placebo-controlled, phase 3 trial at 25 hospitals and polyclinics in Moscow, Russia. We included participants aged at least 18 years, with negative SARS-CoV-2 PCR and IgG and IgM tests, no infectious diseases in the 14 days before enrolment, and no other vaccinations in the 30 days before enrolment. Participants were randomly assigned (3:1) to receive vaccine or placebo, with stratification by age group. Investigators, participants, and all study staff were masked to group assignment. The vaccine was administered (0·5 mL/dose) intramuscularly in a prime-boost regimen: a 21-day interval between the first dose (rAd26) and the second dose (rAd5), both vectors carrying the gene for the full-length SARS-CoV-2 glycoprotein S. The primary outcome was the proportion of participants with PCR-confirmed COVID-19 from day 21 after receiving the first dose. All analyses excluded participants with protocol violations: the primary outcome was assessed in participants who had received two doses of vaccine or placebo, serious adverse events were assessed in all participants who had received at least one dose at the time of database lock, and rare adverse events were assessed in all participants who had received two doses and for whom all available data were verified in the case report form at the time of database lock. The trial is registered at ClinicalTrials.gov ( NCT04530396 ). Findings Between Sept 7 and Nov 24, 2020, 21 977 adults were randomly assigned to the vaccine group (n=16 501) or the placebo group (n=5476). 19 866 received two doses of vaccine or placebo and were included in the primary outcome analysis. From 21 days after the first dose of vaccine (the day of dose 2), 16 (0·1%) of 14 964 participants in the vaccine group and 62 (1·3%) of 4902 in the placebo group were confirmed to have COVID-19; vaccine efficacy was 91·6% (95% CI 85·6–95·2). Most reported adverse events were grade 1 (7485 [94·0%] of 7966 total events). 45 (0·3%) of 16 427 participants in the vaccine group and 23 (0·4%) of 5435 participants in the placebo group had serious adverse events; none were considered associated with vaccination, with confirmation from the independent data monitoring committee. Four deaths were reported during the study (three [<0·1%] of 16 427 participants in the vaccine group and one [<0·1%] of 5435 participants in the placebo group), none of which were considered related to the vaccine. Interpretation This interim analysis of the phase 3 trial of Gam-COVID-Vac showed 91·6% ...

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 anti-SARS-CoV-2 effect of siRNA both in vitro and in vivo.Methods: To identify the 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 showed 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 lung inflammation in animals exposed to 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. The developed medication is intended for inhalation treatment of COVID-19 patients. | 2841KHAITOV eT Al.

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The use of recombinant endolysins is a promising approach for antimicrobial therapy capable of counteracting the spread of antibiotic-resistant strains. To obtain the necessary biotechnological product, diverse peptide tags are often fused to the endolysin sequence to simplify enzyme purification, improve its ability to permeabilize the bacterial outer membrane, etc. We compared the effects of two different types of protein modifications on endolysin LysECD7 bactericidal activity in vitro and demonstrated that it is significantly modulated by specific permeabilizing antimicrobial peptides, as well as by widely used histidine tags. Thus, the tags selected for the study of endolysins and during the development of biotechnological preparations should be used with the appropriate precautions to minimize false conclusions about endolysin properties. Further, modifications of LysECD7 allowed us to obtain a lytic enzyme that was largely devoid of the disadvantages of the native protein and was active over the spectra of conditions, with high in vitro bactericidal activity not only against Gram-negative, but also against Gram-positive, bacteria. This opens up the possibility of developing effective antimicrobials based on N-terminus sheep myeloid peptide of 29 amino acids (SMAP)-modified LysECD7 that can be highly active not only during topical treatment but also for systemic applications in the bloodstream and tissues.

A recombinant vaccine candidate has been developed based on the major coronaviruses’ antigen (S protein) fragments and a novel adjuvant—spherical particles (SPs) formed during tobacco mosaic virus thermal remodeling. The receptor-binding domain and the highly conserved antigenic fragments of the S2 protein subunit were chosen for the design of recombinant coronavirus antigens. The set of three antigens (Co1, CoF, and PE) was developed and used to create a vaccine candidate composed of antigens and SPs (SPs + 3AG). Recognition of SPs + 3AG compositions by commercially available antibodies against spike proteins of SARS-CoV and SARS-CoV-2 was confirmed. The immunogenicity testing of these compositions in a mouse model showed that SPs improved immune response to the CoF and PE antigens. Total IgG titers against both proteins were 9–16 times higher than those to SPs. Neutralizing activity against SARS-CoV-2 in serum samples collected from hamsters immunized with the SPs + 3AG was demonstrated.

Single-domain antibodies (sdAbs, VHHs, or nanobodies) are a promising tool for the treatment of both infectious and somatic diseases. Their small size greatly simplifies any genetic engineering manipulations. Such antibodies have the ability to bind hard-to-reach antigenic epitopes through long parts of the variable chains, the third complementarity-determining regions (CDR3s). VHH fusion with the canonical immunoglobulin Fc fragment allows the Fc-fusion single-domain antibodies (VHH-Fc) to significantly increase their neutralizing activity and serum half-life. Previously we have developed and characterized VHH-Fc specific to botulinum neurotoxin A (BoNT/A), that showed a 1000-fold higher protective activity than monomeric form when challenged with five times the lethal dose (5 LD50) of BoNT/A. During the COVID-19 pandemic, mRNA vaccines based on lipid nanoparticles (LNP) as a delivery system have become an important translational technology that has significantly accelerated the clinical introduction of mRNA platforms. We have developed an mRNA platform that provides long-term expression after both intramuscular and intravenous application. The platform has been extensively characterized using firefly luciferase (Fluc) as a reporter. An intramuscular administration of LNP-mRNA encoding VHH-Fc antibody made it possible to achieve its rapid expression in mice and resulted in 100% protection when challenged with up to 100 LD50 of BoNT/A. The presented approach for the delivery of sdAbs using mRNA technology greatly simplifies drug development for antibody therapy and can be used for emergency prophylaxis.

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