Rapid Rescue of Goose Astrovirus Genome via Red/ET Assembly.

The host-specific infection of Avian Astrovirus (AAstVs) has posed significant challenges to the poultry industry, resulting in substantial economic losses. However, few reports exist on the functional consequences of genome diversity, cross-species infectivity and mechanisms governing virus replication of AAstVs, making it difficult to develop measures to control astrovirus transmission. Reverse genetics technique can be used to study the function of viruses at the molecular level, as well as investigating pathogenic mechanisms and guide vaccine development and disease treatment. Herein, the reverse genetics technique of goose astrovirus GAstV/JS2019 strain was developed based on use of a reconstructed vector including CMV promotor, hammerhead ribozyme (HamRz), hepatitis delta virus ribozyme (HdvRz), and SV40 tail, then the cloned viral genome fragments were connected using Red/ET recombineering. The recombinant rGAstV-JS2019 was readily rescued by transfected the infectious clone plasmid into LMH cells. Importantly, the rescued rGAstV/JS2019 exhibited similar growth kinetics comparable to those of the parental GAstV/JS2019 isolate in cultured cells. Our research results provide an alternative and more effective reverse genetic tool for a detailed understanding of viral replication, pathogenic mechanisms, and molecular mechanisms of evolution.

Recombinant hemagglutinin displaying on yeast reshapes congenital lymphocyte subsets to prompt optimized systemic immune protection against avian influenza infection.

Introduction: Prophylactic vaccination is regarded as the most effective means to control avian flu infection. Currently, there is a need for a universal vaccine that provides broad and long-lasting protection against influenza virus. Meanwhile, although yeast-based vaccines have been used in clinic, studies are still required to further understand the molecular mechanism of yeast-based vaccines under physiological conditions. Methods: We generated a yeast-based vaccine against influenza hemagglutinin (HA) of H5, H7 and H9 using surface displaying technology and evaluated the protective efficacy of chickens after exposure to H9N2 influenza virus. Results: Oral yeast vaccine provided less clinical syndrome, reduced viral loading and alleviated airway damage significantly. Compared to the commercial inactivated vaccine, yeast vaccine stimulated the activation of splenic NK and APCs cells and boosted TLR7-IRF7-IFN signaling in spleen. Meanwhile, γδ T cells in the bursa of Fabricius were activated and the innate lymphoid cells (ILCs) in the bursa of Fabricius promoted the CILPs to differentiate to ILC3 cells in oral yeast birds. Moreover, the reshaped gut microbiota and a suppressed Th17-IL17-mediated inflammation in intestine was observed in oral yeast chickens, which might facilitate the recovery of intestinal mucosal immunity upon virus infection. Collectively, our findings suggest that oral yeast based multivalent bird flu vaccines provide an attractive strategy to update host defense function via reshapes of multi-systemic immune homeostasis.

Hemagglutinin expressed by yeast reshapes immune microenvironment and gut microbiota to trigger diverse anti-infection response in infected birds.

Introduction: The H5N8 influenza virus is a highly pathogenic pathogen for poultry and human. Vaccination is the most effective method to control the spread of the virus right now. The traditional inactivated vaccine, though well developed and used widely, is laborious during application and more interests are stimulated in developing alternative approaches. Methods: In this study, we developed three hemagglutinin (HA) gene-based yeast vaccine. In order to explore the protective efficacy of the vaccines, the gene expression level in the bursa of Fabricius and the structure of intestinal microflora in immunized animals were analyzed by RNA seq and 16SrRNA sequencing, and the regulatory mechanism of yeast vaccine was evaluated. Results: All of these vaccines elicited the humoral immunity, inhibited viral load in the chicken tissues, and provided partial protective efficacy due to the high dose of the H5N8 virus. Molecular mechanism studies suggested that, compared to the traditional inactivated vaccine, our engineered yeast vaccine reshaped the immune cell microenvironment in bursa of Fabricius to promote the defense and immune responses. Analysis of gut microbiota further suggested that oral administration of engineered ST1814G/H5HA yeast vaccine increased the diversity of gut microbiota and the increasement of Reuteri and Muciniphila might benefit the recovery from influenza virus infection. These results provide strong evidence for further clinical use of these engineered yeast vaccine in poultry.

Effects of Corrosion Products Deposited on 304 Stainless Steel on Reduction of Se (IV/VI) in Simulated Groundwater.

Selenium (Se) is a key mobile fission product in the geological disposal of nuclear waste. It is necessary to analyze the reductive deposition behavior of iron-based materials to Se(IV) and Se(VI) in groundwater. In the present work, the corrosion behavior of 304 stainless steel in simulated groundwater (SG) and the effects of corrosion products on the dissolution of Se were investigated by electrochemical and immersion tests. Experimental results revealed that passivation films formed on 304 stainless-steel samples were destroyed by polarization measurements, forming corrosion products consisting of Fe(II) compounds, such as Fe3O4 and FeO. Corrosion products deposited on the surface of steel samples previously treated by polarization measurements in SG + CaCl2/Na2CO3/Na2SiO3 solutions effectively reduced soluble Se(IV) and Se(VI) during immersion tests, depositing FeSe2 on sample surfaces.

Effects of Different Ions and Temperature on Corrosion Behavior of Pure Iron in Anoxic Simulated Groundwater.

As a typical material of the insert in high-level radioactive waste (HLW) geological disposal canisters, iron-based materials will directly contact with groundwater after the failure of a metallic canister, acting as a chemical barrier to prevent HLW leaking into groundwater. In this paper, anoxic groundwater was simulated by mixing 10 mM NaCl and 2 mM NaHCO3 purged by Ar gas (containing 0.3% CO2) with different added ions (Ca2+, CO32- and SiO32-) and operation temperatures (25, 40 and 60 °C). An electrochemical measurement, immersion tests and surface characterization were carried out to study the corrosion behavior of pure iron in the simulated groundwater. The effects of Ca2+ on the corrosion behavior of iron is negligible, however, Cl- plays an important role in accelerating the corrosion activity with the increased concentration and temperature. With increased concentrations of CO32- and SiO32-, the corrosion resistance of iron is largely improved, which is attributed to the formation of a uniform passivation film. The independent effects of temperature on the corrosion behavior of iron are resulted from the repeated passivation-dissolution processes in the formation of the passivation film, resulting from the synergistic effects of CO32-/SiO32- and Cl-. The formation of ferric silicate is dominant in the passivation film with the addition of SiO32-, which effectively protects the iron surface from corrosion.