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
In this work we tested two reagent kits developed by us for detecting SARS-CoV-2 RNA using a fragment of the ORF1ab gene in digital PCR and real-time PCR formats. Data were obtained on the detection of SARS-CoV-2 virus RNA in nasopharyngeal swabs of patients with COVID-19 and asymptomatic carriers. The developed reagent kits provided 100% sensitivity and a detection limit of 103 GE / ml for qPCR, and at least 200 copies / ml of viral RNA when performing digital PCR. These methods were tested using a panel of 1,328 samples collected from patients with suspected COVID-19 at the beginning of 2020 in the Russian Federation. It has been shown that dPCR is more sensitive and can be used to analyze samples with low viral load, including those from patients without clinical symptoms. dPCR significantly improves the accuracy of laboratory research and significantly reduces the number of false negative results in the diagnosis of SARS-CoV-2. Determination of the concentration of SARS-CoV-2 RNA in patients with different clinical course of the disease showed that the concentration of viral RNA can sharply decrease in the first days of the disease. A low concentration of viral RNA in samples from patients is also characteristic of asymptomatic disease. Digital PCR provides a higher detection rate for asymptomatic cases, which is approximately 75% of those infected, as opposed to 45% for real-time PCR. The results obtained on the use of the digital PCR method for detecting SARS-CoV-2 RNA showed that this method is especially suitable for detecting RNA in case of its low concentration in contacts, as well as for monitoring changes in viral load in convalescent patients.