Human infection associated with a novel reassortant avian influenza H7N9 virus has recently been identified in China. A total of 132 confirmed cases and 39 deaths have been reported. Most patients presented with severe pneumonia and acute respiratory distress syndrome. Although the first epidemic has subsided, the presence of a natural reservoir and the disease severity highlight the need to evaluate its risk on human public health and to understand the possible pathogenesis mechanism. Here we show that the emerging H7N9 avian influenza virus poses a potentially high risk to humans. We discover that the H7N9 virus can bind to both avian-type (α2,3-linked sialic acid) and human-type (α2,6-linked sialic acid) receptors. It can invade epithelial cells in the human lower respiratory tract and type II pneumonocytes in alveoli, and replicated efficiently in ex vivo lung and trachea explant culture and several mammalian cell lines. In acute serum samples of H7N9-infected patients, increased levels of the chemokines and cytokines IP-10, MIG, MIP-1β, MCP-1, IL-6, IL-8 and IFN-α were detected. We note that the human population is naive to the H7N9 virus, and current seasonal vaccination could not provide protection.

With no or low virulence in poultry, avian influenza A(H7N9) virus has caused severe infections in humans. In the current fifth epidemic wave, a highly pathogenic avian influenza (HPAI) H7N9 virus emerged. The insertion of four amino acids (KRTA) at the haemagglutinin (HA) cleavage site enabled trypsin-independent infectivity of this virus. Although maintaining dual receptor-binding preference, its HA antigenicity was distinct from low-pathogenic avian influenza A(H7N9). The neuraminidase substitution R292K conferred a multidrug resistance phenotype.

Due to enzootic infections in poultry and persistent human infections in China, influenza A (H7N9) virus has remained a public health threat. The Yangtze River Delta region, which is located in eastern China, is well recognized as the original source for H7N9 outbreaks. Based on the evolutionary analysis of H7N9 viruses from all three outbreak waves since 2013, we identified the Pearl River Delta region as an additional H7N9 outbreak source. H7N9 viruses are repeatedly introduced from these two sources to the other areas, and the persistent circulation of H7N9 viruses occurs in poultry, causing continuous outbreak waves. Poultry movements may contribute to the geographic expansion of the virus. In addition, the AnH1 genotype, which was predominant during wave 1, was replaced by JS537, JS18828, and AnH1887 genotypes during waves 2 and 3. The establishment of a new source and the continuous evolution of the virus hamper the elimination of H7N9 viruses, thus posing a long-term threat of H7N9 infection in humans. Therefore, both surveillance of H7N9 viruses in humans and poultry and supervision of poultry movements should be strengthened. IMPORTANCESince its occurrence in humans in eastern China in spring 2013, the avian H7N9 viruses have been demonstrating the continuing pandemic threat posed by the current influenza ecosystem in China. As the viruses are silently circulated in poultry, with potentially severe outcomes in humans, H7N9 virus activity in humans in China is very important to understand. In this study, we identified a newly emerged H7N9 outbreak source in the Pearl River Delta region. Both sources in the Yangtze River Delta region and the Pearl River Delta region have been established and found to be responsible for the H7N9 outbreaks in mainland China.

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An amine-functionalized succinyl chitosan and an oxidized dextran were synthesized and mixed in aqueous solution to form an in situ chitosan/dextran injectable, surgical hydrogel for adhesion prevention. Rheological characterization showed that the rate of gelation and moduli were tunable based on amine and aldehyde levels, as well as polymer concentrations. The CD hydrogels have been shown to be effective post-operative aids in prevention of adhesions in ear, nose, and throat surgeries and abdominal surgeries in vivo. In vitro biocompatibility testing was performed on CD hydrogels containing one of two oxidized dextrans, an 80 % oxidized (CD-100) or 25 % (CD-25) oxidized dextran. However, the CD-100 hydrogel showed moderate cytotoxicity in vitro to Vero cells. SC component of the CD hydrogel, however, showed no cytotoxic effect. In order to increase the biocompatibility of the hydrogel, a lower aldehyde level hydrogel was developed. CD-25 was found to be non-cytotoxic to L929 fibroblasts. The in vivo pro-inflammatory response of the CD-25 hydrogel, after intraperitoneal injection in BALB/c mice, was also determined by measuring serum TNF-α levels and by histological analysis of tissues. TNF-α levels were similar in mice injected with CD-25 hydrogel as compared to the negative saline injected control; and were significantly different (P < 0.05) as compared to the positive, lipopolysaccharide, injected control. Histological examination revealed no inflammation seen in CD hydrogel injected mice. The results of these in vitro and in vivo studies demonstrate the biocompatibility of the CD hydrogel as a post-operative aid for adhesion prevention.

BackgroundInfluenza A virus can infect a wide variety of animal species including humans, pigs, birds and other species. Viral ribonucleoprotein (vRNP) was involved in genome replication, transcription and host adaptation. Currently, firefly luciferase (Fluc) reporter system was used in vRNP functional assay. However, its limitation for the testing by virus infection resulted in an increased need for rapid, sensitive, and biosafe techniques. Here, an influenza A virus UTR-driven gene reporter for vRNP assay based on secreted Gaussia luciferase (Gluc) activity was evaluated.ResultsBy measuring Gluc levels in supernatants, reporter gene activity could be detected and quantitated after either reconstitution of influenza A virus polymerase complex or viral infection of 293T and A549 cells, respectively. As compared with Fluc reporter, Gluc-based reporter was heat-tolerant (65°C for 30 min) and produced 50-fold higher bioluminescent activity at 24 h posttransfection. Signals generated by Gluc reporter gene could be detected as early as 6 h post-infection and accumulated with time. Testing by viral infection, stronger signals were detected by Gluc reporter at a MOI of 0.001 than that of 1 and the effects of PB2-627K/E or amantadine on influenza vRNP activity were elucidated more effectively by the Gluc reporter system.ConclusionsThis approach provided a rapid, sensitive, and biosafe assay of influenza vRNP function, particularly for the highly pathogenic avian influenza viruses.

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Si-containing bioactive ionic products released from silicate-based bioceramics activate Smad1/5-mediated BMP2 signaling pathways.