Acute respiratory infections (ARIs) cause a considerable morbidity and mortality worldwide especially in children. However, there are few studies of the etiological structure of ARIs in Russia. In this work, we analyzed the etiology of ARIs in children (0–15 years old) admitted to Novosibirsk Children’s Municipal Clinical Hospital in 2013–2017. We tested nasal and throat swabs of 1560 children with upper or lower respiratory infection for main respiratory viruses (influenza viruses A and B, parainfluenza virus types 1–4, respiratory syncytial virus, metapneumovirus, four human coronaviruses, rhinovirus, adenovirus and bocavirus) using a RT-PCR Kit. We detected 1128 (72.3%) samples were positive for at least one virus. The most frequently detected pathogens were respiratory syncytial virus (358/1560, 23.0%), influenza virus (344/1560, 22.1%), and rhinovirus (235/1560, 15.1%). Viral co-infections were found in 163 out of the 1128 (14.5%) positive samples. We detected significant decrease of the respiratory syncytial virus-infection incidence in children with increasing age, while the reverse relationship was observed for influenza viruses. We evaluated the distribution of respiratory viruses in children with ARIs and showed the prevalence of respiratory syncytial virus and influenza virus in the etiological structure of infections. This study is important for the improvement and optimization of diagnostic tactics, control and prevention of the respiratory viral infections.

A wide range of human respiratory viruses are known that may cause acute respiratory infections (ARIs), such as influenza A and B viruses (HIFV), respiratory syncytial virus (HRSV), coronavirus (HCoV), parainfluenza virus (HPIV), metapneumovirus (HMPV), rhinovirus (HRV), adenovirus (HAdV), bocavirus (HBoV), and others. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the COronaVIrus Disease (COVID) that lead to pandemic in 2019 and significantly impacted on the circulation of ARIs. The aim of this study was to analyze the changes in the epidemic patterns of common respiratory viruses among children and adolescents hospitalized with ARIs in hospitals in Novosibirsk, Russia, from November 2019 to April 2022. During 2019 and 2022, nasal and throat swabs were taken from a total of 3190 hospitalized patients 0–17 years old for testing for HIFV, HRSV, HCoV, HPIV, HMPV, HRV, HAdV, HBoV, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by real-time PCR. The SARS-CoV-2 virus dramatically influenced the etiology of acute respiratory infections among children and adolescents between 2019 and 2022. We observed dramatic changes in the prevalence of major respiratory viruses over three epidemic research seasons: HIFV, HRSV, and HPIV mainly circulated in 2019–2020; HMPV, HRV, and HCoV dominated in 2020–2021; and HRSV, SARS-CoV-2, HIFV, and HRV were the most numerous agents in 2021–2022. Interesting to note was the absence of HIFV and a significant reduction in HRSV during the 2020–2021 period, while HMPV was absent and there was a significant reduction of HCoV during the following epidemic period in 2021–2022. Viral co-infection was significantly more frequently detected in the 2020–2021 period compared with the other two epidemic seasons. Certain respiratory viruses, HCoV, HPIV, HBoV, HRV, and HAdV, were registered most often in co-infections. This cohort study has revealed that during the pre-pandemic and pandemic periods, there were dramatic fluctuations in common respiratory viruses registered among hospitalized patients 0–17 years old. The most dominant virus in each research period differed: HIFV in 2019–2020, HMPV in 2020–2021, and HRSV in 2021–2022. Virus–virus interaction was found to be possible between SARS-CoV-2 and HRV, HRSV, HAdV, HMPV, and HPIV. An increase in the incidence of COVID-19 was noted only during the third epidemic season (January to March 2022).

To discover sources for novel anti-influenza drugs, we evaluated the antiviral potential of nine extracts from eight medicinal plants and one mushroom (Avena sativa L., Hordeum vulgare Linn. var. nudum Hook. f., Hippophae rhamnoides Linn., Lycium ruthenicum Murr., Nitraria tangutorum Bobr., Nitraria tangutorum Bobr. by-products, Potentilla anserina L., Cladina rangiferina (L.) Nyl., and Armillaria luteo-virens) from the Qinghai–Tibetan plateau against the influenza A/H3N2 virus. Concentrations lower than 125 μg/mL of all extracts demonstrated no significant toxicity in MDCK cells. During screening, seven extracts (A. sativa, H. vulgare, H. rhamnoides, L. ruthenicum, N. tangutorum, C. rangiferina, and A. luteo-virens) exhibited antiviral activity, especially the water-soluble polysaccharide from the fruit body of the mushroom A. luteo-virens. These extracts significantly reduced the infectivity of the human influenza A/H3N2 virus in vitro when used at concentrations of 15.6–125 μg/mL. Two extracts (N. tangutorum by-products and P. anserina) had no A/H3N2 virus inhibitory activity. Notably, the extract obtained from the fruits of N. tangutorum and N. tangutorum by-products exhibited different anti-influenza effects. The results suggest that extracts of A. sativa, H. vulgare, H. rhamnoides, L. ruthenicum, N. tangutorum, C. rangiferina, and A. luteo-virens contain substances with antiviral activity, and may be promising sources of new antiviral drugs.

The emergence of novel highly pathogenic avian influenza viruses (HPAIVs) in migratory birds raises serious concerns as these viruses have the potential to spread during fall migration. We report the identification of novel HPAIV A(H5N8) clade 2.3.4.4 virus that was isolated from sick domestic duck at commercial farm during the second wave of spread that began in October and affected poultry (ducks; chiсkens) in several European regions of Russia and Western Siberia in 2016. The strain was highly lethal in experimental infection of chickens and mice with IVPI = 2.34 and MLD50 = 1.3log10⁡EID50, accordingly. Inoculation of chickens with the HPAIV A/H5N8 demonstrated neuroinvasiveness, multiorgan failure, and death of chickens on the 3rd day post inoculation. Virus replicated in all collected organ samples in high viral titers with the highest titer in the brain (6.75±0.1 log10TCID50/ml). Effective virus replication was found in the following cells: neurons and glial cells of a brain; alveolar cells and macrophages of lungs; epithelial cells of a small intestine; hepatocytes and Kupffer cells of a liver; macrophages and endothelial cells of a spleen; and the tubular epithelial cells of kidneys. These findings advance our understanding of histopathological effect of A(H5N8) HPAIV infection.