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The expansion and standardization of clinical trials, as well as the use of sensitive and specific molecular diagnostics methods, provide new information on the age-specific roles of influenza and other respiratory viruses in development of severe acute respiratory infections (SARI). Here, we present the results of the multicenter hospital-based study aimed to detect age-specific impact of influenza and other respiratory viruses (ORV). The 2018–2019 influenza season in Russia was characterized by co-circulation of influenza A(H1N1)pdm09 and A(H3N2) virus subtypes which were detected among hospitalized patients with SARI in 19.3% and 16.4%, respectively. RSV dominated among ORV (15.1% of total cases and 26.8% in infants aged ≤ 2 years). The most significant SARI agents in intensive care units were RSV and influenza A(H1N1)pdm09 virus, (37.3% and 25.4%, respectively, of PCR-positive cases). Hyperthermia was the most frequently registered symptom for influenza cases. In contrast, hypoxia, decreased blood O2 concentration, and dyspnea were registered more often in RSV, rhinovirus, and metapneumovirus infection in young children. Influenza vaccine effectiveness (IVE) against hospitalization of patients with PCR-confirmed influenza was evaluated using test-negative case–control design. IVE for children and adults was estimated to be 57.0% and 62.0%, respectively. Subtype specific IVE was higher against influenza A(H1N1)pdm09, compared to influenza A(H3N2) (60.3% and 45.8%, respectively). This correlates with delayed antigenic drift of the influenza A(H1N1)pdm09 virus and genetic heterogeneity of the influenza A(H3N2) population. These studies demonstrate the need to improve seasonal influenza prevention and control in all countries as states by the WHO Global Influenza Strategy for 2019–2030 initiative.

Two variants of highly pathogenic avian influenza A(H5N8) virus were detected in dead poultry in Western Siberia, Russia, during August and September 2020. One variant was represented by viruses of clade 2.3.4.4b and the other by a novel reassortant between clade 2.3.4.4b and Eurasian low pathogenicity avian influenza viruses circulating in wild birds.

Pigs play an important role in interspecies transmission of the influenza virus, particularly as “mixing vessels” for reassortment. Two influenza A/H1N1 virus strains, A/swine/Siberia/1sw/2016 and A/swine/Siberia/4sw/2017, were isolated during a surveillance of pigs from private farms in Russia from 2016 to 2017. There was a 10% identity difference between the HA and NA nucleotide sequences of isolated strains and the most phylogenetically related sequences (human influenza viruses of 1980s). Simultaneously, genome segments encoding internal proteins were found to be phylogenetically related to the A/H1N1pdm09 influenza virus. In addition, two amino acids (129–130) were deleted in the HA of A/swine/Siberia/4sw/2017 compared to that of A/swine/Siberia/1sw/2016 HA.

The results of experimental and clinical trials of the agents based on oncolytic Newcastle disease virus (NDV) strains provided hope for the development of virotherapy as a promising method for treating human tumors. However, the mechanism of the antitumor effect of NDV and realization of its cytotoxic potential in a cancer cell remains to be elucidated. In the current work, we have studied the antitumor effect of NDV in a syngeneic model of mouse Krebs-2 carcinoma treated with intratumoral injections of a wild-type strain NDV/Altai/pigeon/770/2011. Virological methods were used for preparation of a virus-containing sample. Colorimetric MTS assay was used to assess the viability of Krebs-2 tumor cells infected with a viral strain in vitro. In vivo virotherapy was performed in eight-week-old male BALB/c mice treated with serial intratumoral injections of NDV in an experimental model of Krebs-2 solid carcinoma. Changes in the tumor nodes of Krebs-2 carcinoma after virotherapy were visualized by MRI and immunohistological staining. Light microscopy examination, immunohistochemical and morphometric analyses have shown that intratumoral viral injections contribute to the inhibition of tumor growth, appearance of necrosis-like changes in the tumor tissue and the antiangiogenic effect of the virus. It has been established that a course of intratumoral virotherapy with NDV/Altai/pigeon/770/2011 strain in a mouse Krebs-2 carcinoma resulted in increased destructive changes in the tumor tissue, in the volume density of necrotic foci and numerical density of endothelial cells expressing CD34 and VEGFR. These results indicate that intratumoral NDV injection reduces tumor progression of an aggressive tumor.

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&reg, SPBNIIVS, Saint Petersburg, Russia) showed effectiveness against the mouse-adapted influenza B virus.

Marine mammals are widely distributed and can be found almost in all coastal waters and coastlines around the world. The interface areas between marine and terrestrial environments provide natural habitats for aquatic and semiaquatic mammals as well as for reservoir species of avian influenza viruses (AIV) (Runstadler et al. 2013). Previous studies showed that wild aquatic birds, the natural reservoir of AIV, are able to transmit the virus to various mammals, including seals, swine, horses, muskrats, and humans (Webster et al. 1992; Reperant et al. 2009; Gulyaeva et al. 2017). Close contacts between sea mammals and wild birds on breeding-grounds could promote both interspecies transmission of AIV and virus establishment in a new host (Fereidouni et al. 2014). Various AIV subtypes (A/seal/ Massachusetts/80(H7N7), A/Seal/MA/133/82(H4N5), A/Seal/MA/3807/91(H4N6), A/Seal/MA/3911/92(H3N3), A/harbour seal/Mass/1/2011(H3N8) and A/harbor seal/NL/ PV14-221_ThS/2015(H10N7) etc.) have been isolated from different species of marine mammals during the last 30 years. AIV isolated from marine mammals and wild birds are closely related, which suggests that wild birds are the major source of AIV infection (Fereidouni et al. 2014; Bodewes et al. 2015). In addition, AIV can cross species barrier and replicate well in experimental mammals without prior adaptation (Driskell et al. 2012).

Antiviral efficiency of oxidized dextrans (OD) with different molecular weights and oxidation degree (OD40min, OD70min, OD40max, and OD70 max) was studied in vitro and in vivo. Dextrans OD40max and OD70max prevented the development of the cytopathic effect of influenza A(H1N1)pdm09 virus in more than 50% MDCK cells vs. control (no OD). Four intranasal doses of OD40min, OD40max, and OD70min and one intranasal dose of OD70max before infection of BALB/c mice with A(H1N1)pdm09 influenza virus significantly reduced mortality and prolonged life span in comparison with controls receiving saline. These and our previous data attest to clear-cut preventive effect of OD in influenza infection.

To elucidate the evolutionary pathway, we sequenced the entire genomes of 89 H5N6 highly pathogenic avian influenza viruses (HPAIVs) isolated in Japan during winter 2016–2017 and 117 AIV/HPAIVs isolated in Japan and Russia. Phylogenetic analysis showed that at least 5 distinct genotypes of H5N6 HPAIVs affected poultry and wild birds during that period. Japanese H5N6 isolates shared a common genetic ancestor in 6 of 8 genomic segments, and the PA and NS genes demonstrated 4 and 2 genetic origins, respectively. Six gene segments originated from a putative ancestral clade 2.3.4.4 H5N6 virus that was a possible genetic reassortant among Chinese clade 2.3.4.4 H5N6 HPAIVs. In addition, 2 NS clusters and a PA cluster in Japanese H5N6 HPAIVs originated from Chinese HPAIVs, whereas 3 distinct AIV-derived PA clusters were evident. These results suggest that migratory birds were important in the spread and genetic diversification of clade 2.3.4.4 H5 HPAIVs.

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.

Thirty-two muskrats (Ondatra zibethicus) were captured for surveillance of avian influenza virus in wild waterfowl and mammals near Lake Chany, Western Siberia, Russia. A/muskrat/Russia/63/2014 (H2N2) was isolated from an apparently healthy muskrat using chicken embryos. Based on phylogenetic analysis, the hemagglutinin and neuraminidase genes of this isolate were classified into the Eurasian avian-like influenza virus clade and closely related to low pathogenic avian influenza viruses (LPAIVs) isolated from wild water birds in Italy and Sweden, respectively. Other internal genes were also closely related to LPAIVs isolated from Eurasian wild water birds. Results suggest that interspecies transmission of LPAIVs from wild water birds to semiaquatic mammals occurs, facilitating the spread and evolution of LPAIVs in wetland areas of Western Siberia.

Over the years influenza B virus (IBV) contribute annual disease and can lead to serious respiratory disease among humans. More attention should be paid to the mammalian adaptive processes of B viruses and development of vaccines against current influenza. Because of preclinical trials of anti-influenza drugs are conducted mainly on mice, we developed adequate animal model using antigenically-relevant IBV strain for testing anti-influenza drugs and protective efficacy of flu vaccines. We serially passaged Victoria lineage (clade 1A) IBV 17 times in BALB/c mice. The adaptive amino acid substitutions were found in HA (T214I) and NA (D432N). By the electron microscopic examination, we showed spherical and elliptical shapes of IBV. Light microscopy showed that mouse-adapted B virus caused influenza pneumonia on day 6 post inoculation. We evaluated the illness pathogenicity, viral load and histopathological features of mouse-adapted IBV and estimated anti-influenza drugs and vaccine efficiency in vitro and in vivo. Assessment of investigational anti-influenza drug oseltamivir ethoxisuccinate and flu vaccine Ultrix® revealed effectivity against our mouse-adapted influenza B virus.

This work describes the nearly complete genome sequence of Newcastle disease virus (NDV) strain NDV/Novosibirsk/garganey/27/2014, which was isolated from a wild garganey in western Siberia, Russia. The NDV strain was classified as belonging to class II of genotype I and was identified as having recent common ancestry with isolates from wild and domestic birds in China and South Korea.

Summary Constant surveillance of live poultry markets (LPMs) is currently the best way to predict and identify emerging avian influenza viruses (AIVs) that pose a potential threat to public health. Through surveillance of LPMs from 16 provinces and municipalities in China during 2014–2016, we identified 3,174 AIV-positive samples and isolated and sequenced 1,135 AIVs covering 31 subtypes. Our analysis shows that H5N6 has replaced H5N1 as one of the dominant AIV subtypes in southern China, especially in ducks. Phylogenetic analysis reveals that H5N6 arose from reassortments of H5 and H6N6 viruses, with the hemagglutinin and neuraminidase combinations being strongly lineage specific. H5N6 viruses constitute at least 34 distinct genotypes derived from various evolutionary pathways. Notably, genotype G1.2 virus, with internal genes from the chicken H9N2/H7N9 gene pool, was responsible for at least five human H5N6 infections. Our findings highlight H5N6 AIVs as potential threats to public health and agriculture.

A novel Clade 2.3.2.1c H5N1 reassortant virus caused several outbreaks in wild birds in some regions of China from late 2014 to 2015. Based on the genetic and phylogenetic analyses, the viruses possess a stable gene constellation with a Clade 2.3.2.1c HA, a H9N2-derived PB2 gene and the other six genes of Asian H5N1-origin. The Clade 2.3.2.1c H5N1 reassortants displayed a high genetic relationship to a human H5N1 strain (A/Alberta/01/2014). Further analysis showed that similar viruses have been circulating in wild birds in China, Russia, Dubai (Western Asia), Bulgaria and Romania (Europe), as well as domestic poultry in some regions of Africa. The affected areas include the Central Asian, East Asian-Australasian, West Asian-East African, and Black Sea/Mediterranean flyways. These results show that the novel Clade 2.3.2.1c reassortant viruses are circulating worldwide and may have gained a selective advantage in migratory birds, thus posing a serious threat to wild birds and potentially humans. [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s12250-016-3750-4 and is accessible for authorized users.

Early fibrosis of the visceral organs is one of the main complications of infection caused by influenza A virus. Structural manifestations and molecular regulators of the epithelialmesenchymal transformation as a possible mechanism of fibrosis progression were studied in mice infected with influenza A/H1N1 A/Tomsk/13/2010 virus. We found early fibrosis of the lungs against the background of minor changes in fibroblast count. However, enhanced expression of TGF-β and SMAD-2 by macrophages and alveolocytes attested to possible development of epithelial-mesenchymal transformation and its contribution to activation of fibrogenesis process in the lungs.

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.

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.

We report here the genome sequence of the influenza A virus strain A/swine/Siberia/1sw/2016, isolated from a swine in Russia. On the basis of sequence analysis, A/swine/Siberia/1sw/2016 is characterized by unusual surface glycoproteins phylogenetically distinct from those of swine A(H1N1)pdm09 influenza virus.

Newcastle disease virus (NDV) is not considered as cause of serious disease in humans. But, recent data make it clear that, under particular circumstances, it is indeed possible for NDV to cause severe human respiratory disease. Newcastle Disease infection has been reported in many bird species. Cormorants that inhabit at the Qinghai-Tibet Plateau are mainly represented by Great Cormorant (Phalacrocorax carbo sinensis), which is distributed mainly on the Qinghai Lake area. Cormorants are considered as one of the main NDV-reservoir. We conducted the study for the presence of antibodies to Newcastle disease virus by hemagglutination inhibition test in yolks. We got 50% of seropositive yolks to Newcastle disease virus. These results show that NDV circulates in the Qinghai Lake population of cormorants. We first used the technique of detection of antibodies to Newcastle disease virus in the egg yolk for study the circulation of the virus in cormorants and demonstrated its effectiveness. We should carefully monitor cases of pneumonia in the population of people living around the lake and assess the causes of the disease.

Five-hundred-and-six Hyalomma anatolicum ticks were collected and studied in two Crimean-Congo hemorrhagic fever (CCHF) endemic regions of Tajikistan. Antigen and RNA of the CCHF virus were detected in 3.4% of tick pools from the Rudaki district using ELISA and RT-PCR tests. As for the Tursunzade district, viral antigen was identified in 9.0% of the samples and viral RNA was identified in 8.1% of the samples. Multiple alignment of the obtained nucleotide sequences of a region of the S-segment of the genome of the CCHF virus 287 nucleotides in length (996–1282) and the multiple alignment of the deduced amino-acid sequences of the samples carried out to compare with CCHF virus strains from the GenBank database, as well as their phylogenetic analysis, enabled us to conclude that the Asia 1 and Asia 2 genotypes of the CCHF virus are circulating in Tajikistan. It is important to note that the genotype Asia 1 virus was detected in Tajikistan for the first time.

Influenza and other respiratory viral infections account for 80%-90% of infectious pathologies. Influenza A (H5N1) virus has an apparent pneumotropism, and therefore the lung compartment of mononuclear phagocyte system plays an important role in antiviral immunity. Lung macrophages are active phagocytes expressing variety of antiviral factors. The investigation of morphofunctional status of lung macrophages and evaluation of their role in mammal antiviral response in a mouse model were performed within the study. Methods: Light microscopy using standard hematoxylin-eosin, and Van-Gizon’s picrofuchsin staining. Immunohistochemistry using influenza A antigen marker specific primary antibodies, myeloperoxidase, cathepsin D, lysozyme, NO synthase, pro-inflammatory cytokines, cells of CD68 macrophage lineage, PCNA proliferative activity. Morphometric and statistical analysis. Results: Influenza A virus antigen was detected in lung macrophages starting from day 1 to day 14 of infection which corresponds with the beginning of convalescence and may be suggestive of prolonged persistence of virus. On the one hand, the cytopathic effects of the virus lead to lung macrophages death mainly via apoptosis through activation of caspase cascade, including caspase-3 and caspase-9. On the other hand, the observed activation of PCNA proliferation marker, perhaps, allows to support the pool of lung macrophages not only by their recruitment from bone marrow but also by their proliferation in situ. The increase of mononuclear phagocyte system cells expressing antiviral factors depended on the stage of infection. In the early stage, there was an increase of number of cells expressing lysozyme, myeloperoxidase, cathepsin D, endothelial NO synthase (eNOS) followed by the increase of number of macrophages expressing inducible NO synthase (iNOS), pro-inflammatory cytokines and interleukins.

Molecular genetic and antigenic features of influenza A/H3N2 virus strains isolated in Western Siberia in 2011 are similar to those of the vaccine strain A/Perth/16/2009 despite a number of unique amino-acid changes. The strains lack specific amino-acid changes in NA protein providing decrease of sensibility to NA inhibitors activity that used in medical practice. Based on phylogenic analysis of HA protein amino-acid sequences examined strains are similar to influenza A/H3N2 virus strains circulating at the moment in Eurasia.

C57Bl/6 mice were intranasally infected with influenza virus A/H5N1 A/goose/Krasnoozerskoye/627/05. The mortality rate of animals reached 70% on day 14 of the disease. The lungs of animals were characterized by necroses, destruction of vessels, hemorrhagic and thrombotic complications, edematous syndrome, and early fibrosis of the interstitium. On days 6-10 after infection, fibrosis was found in the zones of postnecrotic inflammatory infiltration. The expression of lysozyme and myeloperoxidase by pulmonary macrophages was initially increased, but decreased on day 10 of the study. The number of cathepsin D-expressing macrophages was elevated up to the 10th day of examination.

SUMMARY. The study provides the results of avian influenza virus surveillance in Central Asia during 2003–2009. We have analyzed 2604 samples from wild birds. These samples were collected in Kazakhstan (279), Mongolia (650), and Russia (1675). Isolated viruses from samples collected in Mongolia (13 isolates) and in Russia (4 isolates) were described. Virological analysis has shown that six isolates belong to the H3N6 subtype and five isolates belong to the H4N6 subtype. Two H1N1 influenza viruses, one H10N7 virus, two H3N8 viruses, and an H13N8 virus that is new for Central Asia have been also isolated. Samples were taken from birds of six orders, including several species preferring water and semiaquatic biotopes, one species preferring dry plain regions, and one more species that can inhabit both dry and water biotopes.

A study of the basic biological properties of H5N1 subtype strain isolated during an outbreak among wild birds in Russia in 2010 is presented. The study was carried out using conventional methods according to the WHO recommendations. H5N1 influenza virus isolated in Siberia belonged to clade 2.3.2 of the hemagglutinin gene, and phylogenetic analysis was performed. The antigenic characteristics and the basic genetic markers of biological properties were studied. It was shown that all strains were highly pathogenic for chickens and white mice. Thus, it was shown that, in Russia, the 2010 H5N1 virus phylogenetically closely related to Asian variants caused epizootic among wild birds. The potential danger of this variant of the virus for humans was confirmed by different methods. We discussed the possibility of formulating the natural focus of H5N1 influenza.

In total 3566 blood sera samples were collected in the Russian Far East and Central and Western Siberia in 2009–2010. The presence of antibodies to influenza A/H1N1pdm, seasonal H1N1 and H3N2 influenza viruses in the sera was tested in the hemagglutination inhibition test. 29.5% of samples from the Far East were positive to pandemic influenza, this value for Central and Western Siberia is 2-fold lower (12.8% and 11%, respectively). Fifty-six influenza A/H1N1pdm viruses were isolated during 2009–2010 from samples collected in Central and Western Siberia and the Russian Far East. Molecular and genetic properties of 23 strains were studied. Nucleotide and amino-acid sequences of pandemic influenza virus strains were identical (99% identity or more) to reference strain A/California/04/2009. Sporadic substitutions in antigenic sites were detected but did not change antigenic characteristics of strains.

Oxidized dextran is suggested for prevention of infection induced by influenza A/H5N1 viruses, methods of its use and doses are determined. Two intravenous injections of dextran 3 and 1 days before experimental infection of outbred mice by influenza A/H5N1 A/goose/ Krasnoozerskoye/627/05 virus resulted in a high preventive dose-dependent effect: the mean lifespan was 25% prolonged, the mortality decreased 3-fold.

Oncolyic virotherapy is one of the modern experimental techniques to treat human cancers. Here we studied the antitumor activity of wild-type Newcastle disease virus (NDV) isolates from Russian migratory birds. We showed that NDV could selectively kill malignant cells without affecting healthy cells. We evaluated the oncolytic effect of 44 NDV isolates in 4 histogenetically different human cell lines (HCT116, HeLa, A549, MCF7). The safety of the isolates was also tested in normal peripheral blood mononuclear (PBMC) cells. The viability of tumor cell lines after incubation with NDV isolates was evaluated by MTT. All cell lines, except for normal PBMC primary cells, had different degrees of susceptibility to NDV infection. Seven NDV strains had the highest oncolytic activity, and some NDV strains demonstrated oncolytic selectivity for different cell lines. In vivo, we described the intratumoral activity of NDV/Altai/pigeon/770/2011 against subcutaneous non-small cell lung carcinoma using xenograft SCID mice model. All animals were responsive to therapy. Histology confirmed therapy-induced destructive changes and growing necrotic bulk density in tumor tissue. Our findings indicate that wild-type NDV strains selectively kill tumor cells with no effect on healthy PBMC cells, and intratumoral virotherapy with NDV suppresses the subcutaneous tumor growth in SCID mice.

The pathogenesis of a disease caused by Qinghai-like H5N1 influenza virus in BALB/c mice was studied. Clinical, morphological, and immunological characteristics of the experimental infection caused by highly pathogenic A/duck/Tuva/01/06/ (H5N1) virus are described.

Background Wild aquatic birds, reservoir of low-pathogenicity (LP) avian influenza viruses (AIVs), congregate in huge numbers in Western Siberia wetlands, where major intra- and inter-continental bird flyways overlap. In 2005 and 2006, highly pathogenic (HP) AIV H5N1 epizootics affected wild and domestic birds in the Novosibirsk Region. In 2012, we evaluated AIV persistence in Siberian natural and anthropic ecosystems. Methodology/Principal Findings In Novosibirsk Region, 166 wild birds ecologically linked to aquatic environments and 152 domestic waterfowl were examined for AIV isolation in embryonating chicken eggs. Biological samples were obtained by integrating the conventional cloacal swab collection with the harvesting of samples from birds' plumage. Haemagglutinating allantoic fluids were further characterized by serological and molecular methods. In August-September 2012, 17 AIVs, including three H3N8, eight H4N6, two H4N?, one H2N?, one H?N2, and two unsubtyped LPAIVs, were isolated from 15 wild ducks. Whereas comparable proportions of wild Anseriformes (n.118) tested virus isolation (VI)-positive from cloaca and feathers (5.9% vs 8.5%) were detected, the overall prevalence of virus isolation, obtained from both sampling methods, was 2.4 times higher than that calculated on results from cloacal swab examination only (14.4% vs 5.9%). Unlike previously described in this area, the H4N6 antigenic subtype was found to be the prevalent one in 2012. Both cloacal and feather samples collected from domestic waterfowl tested VI-negative. Conclusion/Significance We found lack of evidence for the H5N1 HPAIV circulation, explainable by the poor environmental fitness of HPAIVs in natural ecosystems. Our LPAIV isolation data emphasise the importance of Siberia wetlands in influenza A virus ecology, providing evidence of changes in circulation dynamics of HN antigenic subtypes harboured in wild bird reservoirs. Further studies of isolates, based on bioinformatic approaches to virus molecular evolution and phylogenesis, will be needed to better elucidate mechanisms involved in AIV perpetuation in this area.

Virus budding from the basolateral domain of infected polarized cells could be one of the mechanisms underlying the quick systemic infection induced by Marburg virus (MARV). We found that MARV buds from the basolateral pole of hepatocytes and bile epithelial cells in infected guinea pigs, which leads to the release of infectious virus into the vascular system. Basolateral budding might be orchestrated by the basolaterally located MARV matrix protein VP40, which induces a partial relocalization of MARV glycoprotein from the apical to the basolateral plasma membrane. This redistribution is a prerequisite for budding of infectious virions from the basolateral domain.

We report here the complete genome sequence of a Newcastle disease virus isolate, NDV/Yakutiya/mallard/852/2011, isolated from a mallard in Russia. On the basis of phylogenetic analysis, this strain was clustered into class II genotype Ib.

In the present study, three mouse-adapted variants of influenza A(H1N1)pdm09 virus were obtained by lung-to-lung passages of BALB/c, C57BL/6z and CD1 mice. The significantly increased virulence and pathogenicity of all of the mouse-adapted variants induced 100% mortality in the adapted mice. Genetic analysis indicated that the increased virulence of all of the mouse-adapted variants reflected the incremental acquisition of several mutations in PB2, PB1, HA, NP, NA, and NS2 proteins. Identical amino acid substitutions were also detected in all of the mouse-adapted variants of A(H1N1)pdm09 virus, including PB2 (K251R), PB1 (V652A), NP (I353V), NA (I106V, N248D) and NS1 (G159E). Apparently, influenza A(H1N1)pdm09 virus easily adapted to the host after serial passages in the lungs, inducing 100% lethality in the last experimental group. However, cross-challenge revealed that not all adapted variants are pathogenic for different laboratory mice. Such important results should be considered when using the influenza mice model.

The emergence of novel avian influenza viruses in migratory birds is of concern because of the potential for virus dissemination during fall migration. We report the identification of novel highly pathogenic avian influenza viruses of subtype H5N8, clade 2.3.4.4, and their reassortment with other avian influenza viruses in waterfowl and shorebirds of Siberia.

We report here the complete genome sequence of a Newcastle disease virus (NDV) isolate, NDV/Altai/pigeon/770/2011, isolated from a rock dove in the Russian Federation. On the basis of phylogenetic analysis, this strain was clustered into genotype VIb class II.

To the Editor: Highly pathogenic H5N1 avian influenza virus caused disease outbreaks in poultry and wild birds in several Asian, European, and African countries from 2003 to 2006. This virus caused >90 human deaths in Vietnam, Thailand, People's Republic of China, Indonesia, Turkey, Iraq, and Cambodia (1–3). Hemagglutinin (HA) and neuraminidase (NA) genes of this virus were derived from the Gs/Gd/1/96-like lineage, and 6 genes that encode internal viral proteins were derived from other lineages (1). Highly pathogenic H5N1 virus genetically related to the A/Chicken/Shantou/4231/03 (People's Republic of China) isolate caused disease outbreaks in poultry in Japan from the end of December 2003 to March 2004 (4). In May and June 2005, highly pathogenic H5N1 virus was isolated from migratory birds during disease outbreaks near Lake Qinghai in western People's Republic of China. HA, NA, and nucleoprotein genes of the Qinghai virus were closely related to H5N1 virus A/Chicken/Shantou/4231/03 isolated in People's Republic of China in 2003. Five other viral genes (matrix, PA, PB1, PB2, and nonstructural protein) were closely related to an H5N1 Hong Kong Special Administrative Region, People's Republic of China 2004 isolate (A/Peregrin falcon/HK/D0028/04) and H5N1 virus A/Chicken/Shantou/810/05 isolated in People's Republic of China in 2005 (5,6). In July 2005, domestic poultry began to die in the village of Suzdalka in western Siberia, Russia (Dovolnoe County, Novosibirsk region). Autopsies showed serious alterations in all internal organs tested. Approximately 95%–100% of the lungs were affected, and all serous membranes showed petechial and confluent hemorrhages. The highest concentration of hemorrhages was in the pericardium. Organs from 3 birds (1 turkey and 2 chickens) that had died during this outbreak were further analyzed. Homogenates of lungs, kidneys, and spleens were tested by hemagglutination inhibition (HI) assay. The highest titers, 32 and 16, were observed in the spleen of the turkey and kidneys of the chickens, respectively. H5 influenza A virus was identified in a homogenate of turkey spleen by conventional HI assay (7) with a panel of reference antisera. For the identification of NA subtype, RNA was isolated from turkey spleen homogenate and synthesis of viral cDNA was performed as previously described (7). Amplification by polymerase chain reaction (PCR) and sequencing of an NA gene fragment were performed with in-house primers (sequences of primers are available on request). The nucleotide sequence obtained (547 bp, GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"DQ231243","term_id":"78146121","term_text":"DQ231243"}}DQ231243) showed 100% identity with the NA gene of H5N1 viruses isolated in People's Republic of China in 2005 (e.g., A/Great black-headed gull/Qinghai/1/05) (5,6). Homogenates of bird organs (turkey spleen and chicken kidneys) were injected into the allantoic cavity of 10-day-old embryonated chicken eggs. Three hemagglutinating agents were isolated (titers 1,024–2,048) and identified as H5 influenza A virus (A/Turkey/Suzdalka/Nov-1/05, A/Chicken/Suzdalka/Nov-11/05, and A/Chicken/Suzdalka/Nov-12/05) by reverse transcription–PCR and sequencing (isolation of RNA from allantoic fluid and synthesis of virus cDNA were performed as previously described [7]). PCR amplification and sequencing of a fragment of the HA gene were performed with an in-house primer set for the H5 gene (available on request). Phylogenetic analysis of nucleotide sequences obtained (GenBank accession nos. {"type":"entrez-nucleotide","attrs":{"text":"DQ231242","term_id":"78146106","term_text":"DQ231242"}}DQ231242, {"type":"entrez-nucleotide","attrs":{"text":"DQ231241","term_id":"78146083","term_text":"DQ231241"}}DQ231241, and {"type":"entrez-nucleotide","attrs":{"text":"DQ231240","term_id":"78146041","term_text":"DQ231240"}}DQ231240) indicated that western Siberian 2005 isolates belong to the Gs/Gd/1/96-like lineage and form a cluster with H5N1 viruses isolated from migratory birds in the People's Republic of China in 2005 (5), from poultry in Japan in 2004 (4), and from poultry and humans in Asian countries in 2003 and 2004 (1) (Figure). Deduced amino acid HA cleavage site sequences of all isolates (PQGERRRKKR/GL) corresponded to highly pathogenic Asian H5N1 influenza virus variants (5,6). Figure Phylogenetic tree of H5 hemagglutinin genes of influenza A viruses. The 3 H5 western Siberian 2005 viruses isolated in this study are shaded. Phylogenetic analysis was performed by the neighbor-joining method with the Molecular Evolutionary Genetic Analysis ... To test virulence, 10 six-week-old chickens were intravenously infected with isolate A/Turkey/Suzdalka/Nov-1/05 as previously described (7). All viruses isolated were highly pathogenic (all chickens died within a day of infection). We isolated H5N1 influenza virus from the spleen of a turkey that died during an outbreak in poultry in western Siberia in July 2005. HA and NA genes of this virus were closely related to those of H5N1 avian influenza viruses that caused outbreaks in birds in Asian countries from 2003 to 2005 and in Japan in 2003 and 2004. The corresponding isolate, A/Turkey/Suzdalka/Nov-1/05, from turkey spleen was highly pathogenic for chickens in the laboratory intravenous pathogenicity index test. The origin of this H5N1 virus in western Siberia is not known. Migratory birds could have introduced this virus because western Siberia is located on a flyway of wild birds that migrate in the spring from southeastern Asia. Highly pathogenic Asian H5N1 influenza virus in western Siberia demonstrates spread of these Asian viruses into new areas and suggests a larger geographic distribution.

Double reassortant H13N8 influenza A virus was isolated from gull in Mongolia. The basic virological characteristics were studied. Complete genome sequence analysis indicated the complicated evolutionary history. The PA gene belongs to classical Avian-like lineage and more likely originated from non-gull avian virus pool. Data confirm the state of extensive geographic mosaicism in AIV from gulls in the Northern Hemisphere.

Intranasal infection of outbred male mice with influenza A/H5N1 A/goose/Krasnoozerskoye/627/05 virus led to high (85%) mortality of animals. Morphological studies of liver specimens showed destructive changes in the parenchyma (93.5% hepatocytes), caused by long persistence of the virus in the liver. The virus persistence was conjugated with activation of cellular immunity, manifesting by an increase in the counts of cells with high expression of proinflammatory cytokines (TNF-α) and lysosomal enzymes (lysozyme, cathepsin D). Injections of oxidized dextran 3 and 1 days before infection reduced mortality and 2-fold attenuated destructive changes in the liver, presumably due to prevention of virus penetration into the target cells, modulation of immune reactions, and stimulation of reparative plastic processes.

High levels of macrophages and fibroblasts expressing MMP-2, MMP-9, and MMP-10 against the background of progressing early fibrosis of the lungs (manifesting in an increase in volume density of type I, III, IV, and VI collagens) were found in C57Bl/6 mice infected with influenza A/H5N1 A/goose/Krasnoozerskoye/627/05 virus. Progressing fibrosis of the lungs in infected mice was associated with imbalance of collagen synthesis and degradation processes conjugated with high levels of macrophages and fibroblasts expressing TIMP-2.

Morphological signs of early interstitial fi brosis, developing under conditions of acute viral inflammation (postinfection days 1-14), were observed in C57Bl/6 mice infected with influenza A/H5N1 A/goose/Krasnoozerskoye/627/05 virus. The development of fi brosis was confirmed by an increase in the number of lung cells expressing TNF-α. These changes were recorded in the presence of a many-fold increase in the counts of macrophages and fi broblasts expressing FGF, EGF, and their receptors.

Oxidized dextran (60 kDa) exerted a pronounced preventive effect in laboratory mice infected with avian influenza subtype H5N1 A/Goose/Krasnoozerskoye/627/05 virus, which manifested in a significant increase in mouse lifetime (by 24.4%) and a decrease in mortality rate (3.3-fold). This was probably related to significant alleviation of pathological changes in the lungs and severity of hemodynamic and inflammatory complications and early fibrosis [corrected].

It is shown that in grivets and guinea pigs Marburg's virus reproduces in cells of the mononuclear phagocyte system, in hepatocytes, and in a few endotheliocytes. Marked pathological changes develop in the liver, spleen, and kidneys. A peculiarity of infection in monkeys is the entire absence of morphological manifestations of an inflammatory reaction and of immune system activation. Cells of the mononuclear phagocyte system are thought to play a crucial role in the development of pathological changes in the organism of infected monkeys and guinea pigs.

Structural changes in the brain of outbred mice were studied after infection with influenza A/H5N1 strain isolated in the Novosibirsk region. High mortality was observed after intranasal infection. Examination of brain specimens revealed vasculopathies with thrombosis of the microcirculatory vessels, pericellular and perivascular edema with multifocal ischemic necrosis, hyperplasia of glial cells, caspase-dependent apoptosis of neurons caused by the cytopathic effect of the virus, and hypercytokinemia.

Oncolytic virus therapy is an area in experimental cancer therapy that is under active investigation. A wide variety of viruses have shown huge potent oncolytic activity against human tumors in cell and animal models without major side effects. Several strains have already being tested in clinical trials in patients. Virotherapy is making promising progress for the treatment of malignancies. Nonetheless, when used in patients, the response rate to oncolytic virus is low. One of the main ways to increase oncolytic capacity is to refuse of excessive attenuation and to use the wild type of oncolytic strains. Naturally occurring oncolytic viruses (OVs) have shown their high cancer-targeted antitumor effects with selectively replication and destroying tumor cells while sparing normal cells, because of defects in IFN-signaling pathways in tumor cell lines. Newcastle disease virus (NDV) is one of the promising therapeutic agent for virotherapy. It belongs to avian paramyxovirus (APMV-1) that is able to infect over 240 species of birds and induce severe disease. However, NDV is not a human pathogen. Newcastle disease virus exhibits effectively oncolytic activity in a range of tumors in pre-clinical and clinical studies. We have previously reported in vitro oncolytic effects of three wild NDV strains. Here we demonstrate data that describe oncolytic capacity NDV collection gathered in 2008–2014, Russia. Antitumor effect of NDV strains on a panel of tumor human cell lines (HCT116, MCF7, A549, HeLa, Skbr, H1299) were investigated. Cell viability was examined over 96 hours by MTT assay. Dose-dependent cell cytotoxicity was demonstrated. In vitro study shows the capacity of several wild NDV strains to lyse tumor cell lines. Two strains of them have significant strong oncolytic activity on human tumor cells of various histogenesis. Recent work in our research also describes the results of in vivo experiments. One of them consists of comparing the efficacy of NDV strain to exhibit specific oncolytic activity in C57Bl/6 mice on subcutaneous murine tumors (LLC and B16) . Our results show that both intravenous and intratumoral injections with multiple doses of wild NDV strain lead to survival prolongation in B16- and LLC-bearing mice and prevent tumor development. We demonstrate antitumor activity of NDV/Altai/pigeon/770/2011 against murine KREBS-2 solid tumor in preclinical model on immunocompetent BALB/c mice. Recently we have demonstrated that NDV/Altai/pigeon/770/2011 can destroy murine KREBS-2 cells in vitro. Moreover, in pilot study we have shown that intratumoral NDV injections decrease of tumor volume and result in complete regression of KREBS-2 tumor in MRI images. Here we test intratumoral administration of NDV and show suppression of Krebs-2 tumor growth in intramuscularly allograft model (2.6-fold less size that in untreated group). Importantly, spread of the virus causes significant tumor necrosis in Krebs-2 tumors. By 20 days after virotherapy, widespread necrosis of NDV-treated tumor is observed. We describe that the vast fields of necrosis in NDV-treated group are the results of formation of ischemic foci in tumor tissue with the rapid development of tumor node and slow neoangiogenesis. Histological examinations and morphometric analysis of tumors in NDV-treated and control groups show that the number of blood vessels including the newly formed in the untreated group is significantly higher than in the experimental group. Immunohistochemical staining (CD34, VEGFR) shows that blood vessels in tumor tissue is strongly reduced to 20 days post-treatment and neoangiogenesis progresses in untreated tumor tissue. Thus, results suggest that vascular disruption in the NDV-treated group indicates the virus ability to directly or indirectly affect tumor angiogenesis and regulate tissue trophism in that way. Understanding how and in which step this effect occurs may provide capacity to use oncolytic NDV strains for therapeutic benefit.