Diversity of gammacoronaviruses and deltacoronaviruses in wild birds and poultry in Russia.

Coronaviruses of the genera Gammacoronavirus and Deltacoronavirus are globally widespread and circulate primarily in wild and domestic birds. Prior studies have established frequently occurring crossover events from avian to mammalian reservoirs. However, there is limited understanding of the diversity and geographical distribution of coronaviruses among birds. In this study, the surveillance of coronaviruses in birds in Russia during 2020 revealed the presence of coronaviruses in 12% of samples from birds. Targeted NGS approach was used for the evaluation of genetic diversity based on RdRp gene. While gammacoronviruses were found in both wild birds and poultry, deltacoronaviruses were found in wild birds only and represent the first detections for Russia. A number of cases with the simultaneous detection of gamma- and deltacoronaviruses in one bird was reported. The results of this study highlight the importance of further research concerning the spread and diversity of coronaviruses among birds within and migrating throughout the territory of Russia across the globe.

Re-Emergence of Circulation of Seasonal Influenza during COVID-19 Pandemic in Russia and Receptor Specificity of New and Dominant Clade 3C.2a1b.2a.2 A(H3N2) Viruses in 2021-2022.

The circulation of seasonal influenza in 2020-2021 around the world was drastically reduced after the start of the COVID-19 pandemic and the implementation of mitigation strategies. The influenza virus circulation reemerged in 2021-2022 with the global spread of the new genetic clade 3C.2a1b.2a.2 of A(H3N2) viruses. The purpose of this study was to characterize influenza viruses in the 2021-2022 season in Russia and to analyze the receptor specificity properties of the 3C.2a1b.2a.2 A(H3N2) viruses. Clinical influenza samples were collected at the local Sanitary-and-Epidemiological Centers of Rospotrebnadzor. Whole genome sequencing was performed using NGS. The receptor specificity of hemagglutinin was evaluated using molecular modeling and bio-layer interferometry. Clinical samples from 854 cases of influenza A and B were studied; A(H3N2) viruses were in the majority of the samples. All genetically studied A(H3N2) viruses belonged to the new genetic clade 3C.2a1b.2a.2. Molecular modeling analysis suggested a higher affinity of hemagglutinin of 3C.2a1b.2a.2. A(H3N2) viruses to the α2,6 human receptor. In vitro analysis using a trisaccharide 6'-Sialyl-N-acetyllactosamine receptor analog did not resolve the differences in the receptor specificity of 3C.2a1b.2a.2 clade viruses from viruses belonging to the 3C.2a1b.2a.1 clade. Further investigation of the A(H3N2) viruses is required for the evaluation of their possible adaptive advantages. Constant monitoring and characterization of influenza are critical for epidemiological analysis.