Anti-Influenza Activity of Medicinal Material Extracts from Qinghai–Tibet Plateau

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.

Experimental Infection Using Mouse-Adapted Influenza B Virus in a Mouse Model

Every year, influenza B viruses (IBVs) contribute to annual illness, and infection can lead to serious respiratory disease among humans. More attention is needed in several areas, such as increasing virulence or pathogenicity of circulating B viruses and developing vaccines against current influenza. Since preclinical trials of anti-influenza drugs are mainly conducted in mice, we developed an appropriate infection model, using an antigenically-relevant IBV strain, for furtherance of anti-influenza drug testing and influenza vaccine protective efficacy analysis. A Victoria lineage (clade 1A) IBV was serially passaged 17 times in BALB/c mice, and adaptive amino acid substitutions were found in hemagglutinin (HA) (T214I) and neuraminidase (NA) (D432N). By electron microscopy, spherical and elliptical IBV forms were noted. Light microscopy showed that mouse-adapted IBVs caused influenza pneumonia on day 6 post inoculation. We evaluated the illness pathogenicity, viral load, and histopathological features of mouse-adapted IBVs and estimated anti-influenza drugs and vaccine efficiency in vitro and in vivo. Assessment of an investigational anti-influenza drug (oseltamivir ethoxysuccinate) and an influenza vaccine (Ultrix^®, SPBNIIVS, Saint Petersburg, Russia) showed effectiveness against the mouse-adapted influenza B virus.

Characterization and Phylodynamics of Reassortant H12Nx Viruses in Northern Eurasia

Wild waterfowl birds are known to be the main reservoir for a variety of avian influenza viruses of different subtypes. Some subtypes, such as H2Nx, H8Nx, H12Nx, and H14Nx, occur relatively rarely in nature. During 10-year long-term surveillance, we isolated five rare H12N5 and one H12N2 viruses in three different distinct geographic regions of Northern Eurasia and studied their characteristics. H12N2 from the Far East region was a double reassortant containing hemagglutinin (HA), non-structural (NS) and nucleoprotein (NP) segments of the American lineage and others from the classical Eurasian avian-like lineage. H12N5 viruses contain Eurasian lineage segments. We suggest a phylogeographical scheme for reassortment events associated with geographical groups of aquatic birds and their migration flyways. The H12N2 virus is of particular interest as this subtype has been found in common teal in the Russian Far East region, and it has a strong relation to North American avian influenza virus lineages, clearly showing that viral exchange of segments between the two continents does occur. Our results emphasize the importance of Avian Influenza Virus (AIV) surveillance in Northern Eurasia for the annual screening of virus characteristics, including the genetic constellation of rare virus subtypes, to understand the evolutionary ecology of AIV.

Viral etiology of acute respiratory infections in hospitalized children in Novosibirsk City, Russia (2013 - 2017)

Background

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.

Methods

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.

Results

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.

Conclusions

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.

Molecular determinants possibly involved in the adaptation of pandemic A(H1N1)09 influenza virus to a new host

Aim: To determine the molecular basis of A(H1N1)pdm09 virus adaptation to a new host. Methods: The pandemic virus A/Russia/01/2009 was adapted to mice by serial lung-to-lung passages. The growth properties, pathogenicity and genome sequences of the mouse-adapted virus were compared with those of the parental strain. Results: The A(H1N1)pdm09 virus caused mouse death after only six lung-to-lung passages. Mutations in the influenza virus antigen were found in the brain, liver, kidney and in intestine by immunohistochemistry. Conclusion: Our findings suggest that multiple mutations in the viral genome promote rapid adaptation of the A(H1N1)pdm09 virus and cause generalized infection in mice.