Биоразнообразие и эпидемический потенциал коронавирусов ( Nidovirales: Coronaviridae ) рукокрылых

The COVID-19 pandemic, which began at the end of 2019 in Wuhan, has affected 220 countries and territories to date. In the present study, we studied humoral immunity in samples of the blood sera of COVID-19 convalescents of varying severity and patients who died due to this infection, using native SARS-CoV-2 and its individual recombinant proteins. The cross-reactivity with SARS-CoV (2002) was also assessed. We used infectious and inactivated SARS-CoV-2/human/RUS/Nsk-FRCFTM-1/2020 strain, inactivated SARS-CoV strain (strain Frankfurt 1, 2002), recombinant proteins, and blood sera of patients diagnosed with COVID-19. The blood sera from patients were analyzed by the Virus Neutralization test, Immunoblotting, and ELISA. The median values and mean ± SD of titers of specific and cross-reactive antibodies in blood sera tested in ELISA were mainly distributed in the following descending order: N > trimer S > RBD. ELISA and immunoblotting revealed a high cross-activity of antibodies specific to SARS-CoV-2 with the SARS-CoV antigen (2002), mainly with the N protein. The presence of antibodies specific to RBD corresponds with the data on the neutralizing activity of blood sera. According to the neutralization test in a number of cases, higher levels of antibodies that neutralize SARS-CoV-2 were detected in blood serum taken from patients several days before their death than in convalescents with a ranging disease severity. This high level of neutralizing antibodies specific to SARS-CoV-2 in the blood sera of patients who subsequently died in hospital from COVID-19 requires a thorough study of the role of humoral immunity as well as comorbidity and other factors affecting the humoral response in this disease.

Aim. In vitro analysis of the inhibitory activity of dry ethanol extracts of some Artemisia spp. growing in the Novosibirsk region for SARS‐CoV‐2 replication.Materials and Methods. The laboratory strain SARS‐CoV‐2/human/RUS/Nsk‐FRCFTM‐1/2020 was passed on Vero cell culture. Dry ethanol extracts of plant parts (stems, flowers, leaves) of six types of Artemisia were prepared. The types used were: A. vulgaris L.; A. glauca (Pall. Ex Willd.); A. dracunculus L. (from three growth locations); A. absinthium L.; A. frigida Willd.; and A. sieversiana Ehrh. ex Willd. Dry extracts were dissolved in DMSO. In vitro analysis of the inhibitory activity of extracts against SARS‐CoV‐2 (an infectious titer of 10³ TCID₅₀/ml) replication was performed in a Vero E6 cell culture. To do this, the method of direct inactivation (neutralization) of virions, as well as schemes of “preventive” and “therapeutic” of cells, were used. Comparison samples were dry ethanol extracts of Inonotus obliquus, Syzygium aromaticum L. and Camellia sinensis L.Results. Extracts of leaves of Artemisia spp. proved to be most effective in direct inactivation of virions. By equal and decreasing activity these are the species: A. vulgaris; A. dracunculus*; A. absinthium; A. dracunculus***; A. dracunculus**; A. frigidа; A. glauca; and A. sieversiana with a 50% effective concentration of range 1.10±0.24 – 11.72±2.89 μg/ml. Extracts of flowers of A. vulgaris, A.glauca, A. dracunculus*, A. dracunculus**, A. dracunculus***, A. frigida and A. sieversiana also contain biologically active substances which act both destructively on virions and after the virus has entered cells. For extracts of stems consistently high values of EC₅₀ were found for A. glauca (6.84±1.35; 7.81±2.00 and 14.06±3.06 μg/ml) according to the results of three experimental schemes.Conclusion. The results obtained can become the basis for the development of inexpensive domestic drugs for the treatment and/or prevention of COVID‐19.

Выявление Ehrlichia spp. и Theileria spp. в клещах Hyalomma anatolicum , собранных в Таджикистане