ABSTRACT
The aim of the work was to study the pathogenicity of newly emerging variants of SARS-CoV-2 on the model of the Syrian golden hamster. Materials and methods. We used the strains of SARS-CoV-2 virus related to the VOC circulating in the territory of the Russian Federation. The experiments were carried out on outbreed Syrian hamsters obtained from the nursery of the SSC VB "Vector”. The infectious titer of coronavirus in tissue samples collected from infected laboratory animals was determined on a Vero E6 cell culture. The Ct in RT-PCR was considered an additional parameter for monitoring the viral load in the samples. The severity of lung tissue damage in Syrian hamsters with COVID-19 was assessed by histological preparations. Results and discussion. 50 % infecting doses in case of the intranasal infection have been determined, histological analysis of lung tissues performed. The pathogenicity of various variants of the SARS-CoV-2 virus for the Syrian hamster has been evaluated, differences in infecting doses and pathological changes in the lungs have been revealed. SARS-CoV-2 viruses belonging to Beta genetic variant have the highest virulence, while Alpha variant has the lowest one when comparing the studied strains by the ID50 value. The Delta and Omicron variants have a matched ability to cause specific damage to the tissues of the respiratory tract, while being inferior only to the Beta variant. It has been demonstrated that Syrian hamsters are an adequate model for assessing the pathogenicity of the SARS-CoV-2 virus variants of concern. Variants of SARS-CoV-2 virus during intranasal infection has shown different degree of pathogenicity in the Syrian hamster model. © 2022 Russian Research Anti-Plague Institute. All rights reserved.
ABSTRACT
The purpose of the research was to study the dynamics of residual infectious activity of SARS-CoV-2 virus strains belonging to different genovariants, on different types of surfaces, in samples of drinking dechlorinated water at 24–28 °C, as well as their resistance to disinfectants. Materials and methods. The studies were carried out using SARS-CoV-2 coronavirus strains obtained from the State Collection of Causative Agents of Viral Infectious Diseases and Rickettsiosis, which operates at the premises of the SSC VB “Vector”. The evaluation of the residual infectivity of the SARS-CoV-2 coronavirus was carried out through titration of samples in cell culture. Results and discussion. The conducted studies have confirmed the ability of all investigated strains of the SARS-CoV-2 coronavirus to maintain their infectious activity at 24–28 °C on most of the examined types of test surfaces for at least 48 hours, while the virus is best preserved on stainless steel and plastic. All studied strains of the SARS-CoV-2 coronavirus are viable in drinking dechlorinated water for at least 48 hours. In addition, it has been found that all of them are sensitive to disinfectants of different groups, widely used for disinfection when working with pathogenic biological agents or for treating hands and surfaces contaminated with viruses. Chlorine-containing disinfectants are the most active. Skin antiseptics based on ethyl and isopropyl alcohols are suitable for disinfecting hands and objects contaminated with the SARS-CoV-2 virus. © 2022 Russian Research Anti-Plague Institute. All rights reserved.
ABSTRACT
The aim of the research was to assess the susceptibility of mice of different lines to newly emerging variants of SARS-CoV-2. Materials and methods. The SARS-CoV-2 virus strains belonging to variants of concern (VOC) circulating in the territory of the Russian Federation were used in the study. Experiments involved three inbred mouse lines (BALB/c, CBA and C57Bl/6z) and CD1 outbred mice taken from the nursery of the SSC VB “Vector” of the Rospotrebnadzor. The infectious titer of coronavirus in tissue samples obtained from the laboratory animals was determined on a Vero E6 cell culture. The (Ct) threshold value in RT-PCR was considered an additional parameter for monitoring the viral load in the samples. The severity of lung tissue damage was assessed using histological preparations. Results and discussion. The susceptibility of various mouse lines to the genetic variant Beta of the SARS-CoV-2 virus has been investigated. During intranasal infection of the inbred and outbred mice with strains of VOC at a dose of 2·103 TCID50, the virus replicated in the lungs with maximum concentrations 72 hours after infection. The pathogenicity of genetic variants of the SARS-CoV-2 virus for BALB/c mice has been assessed, a 50 % infectious dose for intranasal infection (ID50) determined. Histological analysis showed COVID-19-specific lung tissue lesions in infected animals. Our study proves that BALB/c mice can be used as a model animal in screening studies when evaluating the effectiveness of therapeutic, vaccine preparations and studying the pathogenesis caused by VOC of the SARS-CoV-2 virus: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Omicron (B.1.1.529) and the like. © 2022 Russian Research Anti-Plague Institute. All rights reserved.
ABSTRACT
The aim of the research was to study reproduction features of SARS-CoV-2 coronavirus strains of various genetic lines on Vero and Vero E6 cell culture. Materials and methods. The SARS-CoV-2 virus strains related to the variants of concern (VOC) circulating in the territory of the Russian Federation were used in the research. The strains of the SARS-CoV-2 virus were deposited in the State Collection of Pathogens of Viral Infections and Rickettsioses at the FBIS SSC VB “Vector” of the Rospotrebnadzor. The experiments were carried out on Vero and Vero E6 cell cultures. The dynamics of infectious virus accumulation was determined by titration of culture fluid samples 24, 48, 72, 96 hours after infection (MOI – from 1 to 0,00001 CPE50/cell). Plaque formation was studied on Vero E6 cell culture under 0.2 % agar coating. Image analysis and plaque size calculation were performed using GIMP (GNU Image Manipulation Program). Results and discussion. The study describes the dynamics of accumulation of infectious virus in the culture fluid depending upon multiplicity of infection for the strains of SARS-CoV-2 virus belonging to different genetic lines. Differences in the morphology of plaques on the monolayer of Vero E6 cell culture under agar coating are shown. SARS-CoV-2 virus strains related to Alfa and Delta VOC demonstrate maximum reproduction rate among the studied strains (infectious titer is higher than 7 lg TCID50/100µl). Omicron VOC forms small plaques under agar coating and at a low multiplicity of infection has a low reproduction rate. Thus, SARS-CoV-2 virus strains belonging to different genetic lines have significant differences in the rate of reproduction on Vero and Vero E6 cell culture. © 2022 Russian Research Anti-Plague Institute. All rights reserved.
ABSTRACT
To analyze the essence of digital transformation and the ways in which it becomes possible. This article focuses on students' reactions, their assessments and views on ongoing online learning. The main research questions posed in the article are: is ongoing digital learning effective? Do students evaluate what happened as a digital transformation in education? What are the main challenges facing ongoing digital learning? © 2022 IEEE.
ABSTRACT
Coronaviridae is a family of single-stranded RNA (ssRNA) viruses that can cause diseases with high mortality rates. SARS-CoV-1 and MERS-CoV appeared in 2002-2003 and 2012, respectively. A novel coronavirus, SARS-CoV-2, emerged in 2019 in Wuhan (China) and has caused more than 5 million deaths in worldwide. The entry of SARS-CoV-1 into the cell is due to the interaction of the viral spike (S) protein and the cell protein, angiotensin-converting enzyme 2 (ACE2). After infection, virus assembly occurs in Golgi apparatus-derived vesicles during exocytosis. One of the possible participants in this process is LAMP1 protein. We established transgenic Vero cell lines with increased expression of human LAMP1 gene and evaluated SARS-CoV-1 and SARS-CoV-2 production. An increase in the production of both viruses in LAMP1-expressing cells when compared with Vero cells was observed, especially in the presence of trypsin during infection. From these results it can be assumed that LAMP1 promotes SARS-CoV-1 and SARS-CoV-2 production due to enhanced exocytosis.