Development, production and characterization of SARS-CoV-2 virus-like particles (Coronaviridae: <i>Orthocoronavirinae: Betacoronavirus: Sarbecovirus</i>)

Introduction. The COVID-19 pandemic caused by SARS-CoV-2 has created serious health problems worldwide. The most effective way to prevent the occurrence of new epidemic outbreaks is vaccination. One of the modern and effective approaches to vaccine development is the use of virus-like particles (VLPs). The aim of the study is to develop a technology for production of VLP based on recombinant SARS-CoV-2 proteins (E, M, N and S) in insect cells. Materials and methods. Synthetic genes encoding coronavirus proteins E, M, N and S were used. VLP with various surface proteins of strains similar to the Wuhan virus, Delta, Alpha and Omicron were developed and cloned into the pFastBac plasmid. The proteins were synthesized in the baculovirus expression system and assembled into VLP in the portable Trichoplusia ni cell. The presence of insertion in the baculovirus genome was determined by PCR. ELISA and immunoblotting were used to study the antigenic activity of VLP. VLP purification was performed by ultracentrifugation using 20% sucrose. Morphology was assessed using electron microscopy and dynamic light scattering. Results. VLPs consisting of recombinant SARS-CoV-2 proteins (S, M, E and N) were obtained and characterized. The specific binding of antigenic determinants in synthesized VLPs with antibodies to SARS-CoV-2 proteins has been demonstrated. The immunogenic properties of VLPs have been studied. Conclusion. The production and purification of recombinant VLPs consisting of full-length SARS-CoV-2 proteins with a universal set of surface antigens have been developed and optimized. Self-assembling particles that mimic the coronavirus virion induce a specific immune response against SARS-CoV-2

Community-acquired pneumonia in children in the era of the COVID-19 pandemic. What has changed?

During COVID-19 pandemic the issue of diagnosis and rational therapy of community-acquired pneumonia in children became acute. This is caused by difficulties in verification of the diagnosis of community-acquired pneumonia in the outpatient department, peculiarities of interpretation of the respiratory system lesions. The article presents clinical cases of communityacquired pneumonia in children admitted to the pulmonology department of a pediatric hospital.Clinical case 1. 5-year-old child, medical history: acutely fell ill, on 28.11.20, had a sore throat and fever up to 39.0 C. Received Kagocel, Miramistin, Nurofen. PCR for COVID-19 on 08.12.20 was positive, on 18.12.2020, 22.12.2020, 20.01.2021 - negative. Immunoassay (ELISA) on 12.23.20: IgM - 4.47, IgG - 255.25. Lung and pleural cavity ultrasound: echo signs of sharply pronounced interstitial syndrome, massive fibrinothorax on both sides, indirect signs of bronchopleural fistulas; lung radiography: bilateral polysegmental pneumonia, bilateral hydrothorax, bilateral fibrinothorax, with no marked progression; CT scan with IV contrast: CT picture of hydrothorax on the left, hydropneumothorax on the right, pleurisy on both sides, compression atelectasis of lower lobe segments of both lungs. With no marked progression. Treatment. Thoracentesis; antibiotic therapy, antimycotics, infusion therapy, immunotherapy, partial parenteral nutrition. Against the background of the therapy, positive dynamics was obtained. Clinical examples are also given: an 8-year-old child with suspected new coronavirus infection and a 5-year-old child with bilateral polysegmental pneumonia