Objective: To understand the molecular characteristics of hemagglutinin (HA) and neuraminidase (NA) as well as the disease risk of influenza virus A H7N9 in Guizhou province. Methods: RNAs were extracted and sequenced from HA and NA genes of H7N9 virus strains obtained from 18 cases of human infection with H7N9 virus and 6 environmental swabs in Guizhou province during 2014-2017. Then the variation and the genetic evolution of the virus were analyzed by using a series of bioinformatics software package. Results: Homology analysis of HA and NA genes revealed that 2 strains detected during 2014-2015 shared 98.8%-99.2% and 99.2% similarities with vaccine strains A/Shanghai/2/2013 and A/Anhui/1/2013 recommended by WHO, respectively. Two strains detected in 2016 and 14 strains detected in 2017 shared 98.2%-99.3% and 97.6%-98.8% similarities with vaccine strain A/Hunan/02650/2016, respectively. Other 6 stains detected in 2017 shared 99.1%-99.4% and 98.9%-99.3% similarities with strain A/Guangdong/17SF003/2016, respectively. Phylogenetic analysis showed that all the strains were directly evolved in the Yangtze River Delta evolution branch, but they were derived from different small branch. PEVPKRKRTAR↓GLF was found in 6 of 24 strains cleavage site sequences of HA protein, indicating the characteristic of highly pathogenic avian influenza virus. Mutations A134V, G186V and Q226L at the receptor binding sites were found in the HA. All the strains had a stalk deletion of 5 amino acid residue "QISNT" in NA protein, and drug resistance mutation R294K occurred in strain A/Guizhou-Danzhai/18980/2017. In addition, potential glycosylation motifs mutations NCS42NCT were found in the NA of 9 of 24 strains. Conclusions: HA and NA genes of avian influenza A (H7N9) virus showed genetic divergence in Guizhou province during 2014-2017. The mutations of key sites might enhance the virulence of the virus, human beings are more susceptible to it. Hence, the risk of infection is increasing.
Animals ; Base Sequence ; Birds ; China/epidemiology* ; Genome, Viral ; Hemagglutinin Glycoproteins, Influenza Virus/immunology* ; Hemagglutinins/genetics* ; Humans ; Influenza A Virus, H7N9 Subtype/isolation & purification* ; Influenza in Birds ; Influenza, Human/virology* ; Neuraminidase/genetics* ; Phylogeny ; RNA, Viral/genetics* ; Sequence Analysis, DNA

The recent human infection with avian influenza virus revealed that H9N2 influenza virus is the gene donor for H7N9 and H10N8 viruses infecting humans. The crucial role of H9N2 viruses at the animal-human interface might be due to the wide host range, adaptation in both poultry and mammalian, and extensive gene reassortment. As the most prevalent subtype of influenza viruses in chickens in China, H9N2 also causes a great economic loss for the poultry industry, even under the long-term vaccination programs. The history, epidemiology, biological characteristics, and molecular determinants of H9N2 influenza virus are reviewed in this paper. The contribution of H9N2 genes, especially RNP genes, to the infection of humans needs to be investigated in the future.
Animals ; Chickens ; virology ; China ; epidemiology ; Humans ; Influenza A Virus, H7N9 Subtype ; genetics ; Influenza A Virus, H9N2 Subtype ; genetics ; immunology ; physiology ; Influenza in Birds ; epidemiology ; transmission ; virology ; Influenza, Human ; epidemiology ; transmission ; virology ; Vaccination ; Viral Proteins ; classification ; metabolism

OBJECTIVETo prepare the 4 candidate vaccine strains of H5N1 avian influenza virus isolated in China.

METHODSRecombinant viruses were rescued using reverse genetics. Neuraminidase (NA) and hemagglutinin (HA) segments of the A/Xinjiang/1/2006, A/Guangxi/1/2009, A/Hubei/1/2010, and A/Guangdong/1/2011 viruses were amplified by RT-PCR. Multibasic amino acid cleavage site of HA was removed and ligated into the pCIpolI vector for virus rescue. The recombinant viruses were evaluated by trypsin dependent assays. Their embryonate survival and antigenicity were compared with those of the respective wild-type viruses.

RESULTSThe 4 recombinant viruses showed similar antigenicity compared with wild-type viruses, chicken embryo survival and trypsin-dependent characteristics.

CONCLUSIONThe 4 recombinant viruses rescued using reverse genetics meet the criteria for classification of low pathogenic avian influenza strains, thus supporting the use of them for the development of seeds and production of pre-pandemic vaccines.

Animals ; Chick Embryo ; Chickens ; China ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; metabolism ; Influenza A Virus, H5N1 Subtype ; immunology ; Influenza Vaccines ; immunology ; Influenza in Birds ; prevention & control ; virology ; Neuraminidase ; genetics ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Vaccines, Synthetic ; immunology

Since 2002, H7 subtype avian influenza viruses (AIVs) have caused more than 100 human infection cases in the Netherlands, Italy, Canada, the United States, and the United Kingdom, with clinical illness ranging from conjunctivitis to mild upper respiratory illness to pneumonia. On March 31st, three fatal cases caused by infection of a novel reassortant H7N9 subtype were reported in Shanghai City and Anhui Province in China. With the ability of H7 subtype to cause severe human disease and the increasing isolation of subtype H7 AIVs, we highlighted the need for continuous surveillance in both humans and animals and characterization of these viruses for the development of vaccines and anti-viral drugs.
Animals ; Chickens ; Ducks ; Humans ; Influenza A virus ; genetics ; isolation & purification ; pathogenicity ; physiology ; Influenza Vaccines ; genetics ; immunology ; Influenza in Birds ; immunology ; prevention & control ; virology ; Influenza, Human ; immunology ; prevention & control ; virology ; Poultry Diseases ; immunology ; prevention & control ; virology ; Turkeys

To clone porcine bone marrow stromal antigen-2 (BST-2) gene, construct its recombinant eukaryotic expression plasmid and induce the expression of the fusion antiviral protein, we amplified BST-2 gene by RT-PCR from the total RNA extracted from PK15 cells. The recombinant expression plasmid pcDNA-BST-2 was constructed and then was transfected into HEK293T cells to expresse the BST-2 fusion protein. Western blot and indirect immunofluorescence assay (IFA) were performed, and the biological activity was detected. The results showed that the construction of recombinant plasmid pcDNA-BST-2 was confirmed by restriction enzyme digestion and sequencing. The expressed product had antiviral activity against Vesicular stomatitis virus (VSV), Avian influenza virus (AIV) and Porcine reproductive and respiratory syndrome virus (PRRSV). In conclusion, the research paves the way for further research on bioactivity assayand antiviral medication.
Animals ; Antigens, CD ; genetics ; immunology ; Cell Line ; Chickens ; Cloning, Molecular ; Gene Expression ; Humans ; Influenza in Birds ; immunology ; virology ; Orthomyxoviridae ; physiology ; Porcine Reproductive and Respiratory Syndrome ; immunology ; virology ; Porcine respiratory and reproductive syndrome virus ; physiology ; Swine ; Vesicular Stomatitis ; immunology ; virology ; Vesicular stomatitis Indiana virus ; physiology ; Virus Replication

OBJECTIVETo survey the distribution of influenza A subtypes in external environment and investigate the infectious status of highly pathogenic avian influenza (H5N1) in poultry-exposed population in Wuhan.

METHODSSeventy-eight external environmental samples (water, cage surface and fecal samples) were collected from 3 habitats of wild migratory birds and 5 urban live-poultry markets in 2010. In 13 avian influenza monitoring points, 249 serum samples were collected from people living around habitats of wild migratory birds or working in live poultry markets. Real-time RT-PCR method was adopted to detect influenza A virus from external environmental samples; and multiple RT-PCR method and specific H3, H5, H7 and H9 primers were then applied to analyze the subtypes of the positive samples. The levels of H5N1 antibody in poultry-exposed population were tested by horse hemagglutination inhibition test and two avian influenza inactivated antigens: A/Hubei/1/10 and A/Anhui/1/05.

RESULTSOf the 50 external environmental samples collected from live poultry markets, 17 samples were determined to be influenza A virus positive (positive rate 34.0%), including specific subtypes as follows: 4 samples of H5 single-positive subtype, 3 samples of H9 single-positive subtype, 4 samples of H3 and H5 mixed-positive subtype, 2 samples of H3 and H9 mixed-positive subtype, 2 samples of H5 and H9 mixed-positive subtype, 2 samples of H3, H5 and H9 mixed-positive subtype, but no H7 positive subtype was found. The 28 external environmental samples collected from habitats of wild migratory birds were all influenza A virus negative. Considering different types of external environmental samples, the influenza A virus positive rates in water, cage surface and fecal samples were 37.5% (6/16), 16.7% (5/30) and 18.8% (6/32), respectively. There were total 100 samples of serum whose A/Hubei/1/10 antigen inhibiting titers ≥ 40, accounting for 40.2%; while 36 samples of serum (14.5%) whose A/Anhui/1/05 antigen inhibiting titers ≥ 40 were found. The difference had statistical significance (χ(2) = 41.433, P < 0.05). Among the 249 serum samples collected from poultry-exposed population, 5 samples were H5N1 antibody positive against A/Hubei/1/10 antigen (inhibition titer ≥ 160), which came from 4 different live poultry markets, however, no positive serum sample against A/Anhui/1/05 antigen was found.

CONCLUSIONMultiple subtypes of avian influenza virus simultaneously prevailed in Wuhan urban poultry markets. Moreover, results from the distribution of avian influenza virus in external environment were consistent with the level of H5N1 antibody in poultry-exposed population.

Animals ; Antibodies, Viral ; blood ; Birds ; virology ; China ; Environment ; Humans ; Influenza A Virus, H5N1 Subtype ; immunology ; Occupational Exposure ; Poultry ; virology

Influenza vaccine strains have been traditionally developed by annual reassortment between vaccine donor strain and the epidemic virulent strains. The classical method requires screening and genotyping of the vaccine strain among various reassortant viruses, which are usually laborious and time-consuming. Here we developed an efficient reverse genetic system to generate the 6:2 reassortant vaccine virus from cDNAs derived from the influenza RNAs. Thus, cDNAs of the two RNAs coding for surface antigens, haemagglutinin and neuraminidase from the epidemic virus and the 6 internal genes from the donor strain were transfected into cells and the infectious viruses of 6:2 defined RNA ratio were rescued. X-31 virus (a high-growth virus in embryonated eggs) and its cold-adapted strain X-31 ca were judiciously chosen as donor strains for the generation of inactivated vaccine and live-attenuated vaccine, respectively. The growth properties of these recombinant viruses in embryonated chicken eggs and MDCK cell were indistinguishable as compared to those generated by classical reassortment process. Based on the reverse genetic system, we generated 6 + 2 reassortant avian influenza vaccine strains corresponding to the A/Chicken/Korea/MS96 (H9N2) and A/Indonesia/5/2005 (H5N1). The results would serve as technical platform for the generation of both injectable inactivated vaccine and the nasal spray live attenuated vaccine for the prevention of influenza epidemics and pandemics.
Animals ; Chick Embryo ; Chickens ; Genetic Engineering ; Hemagglutinins, Viral/genetics/metabolism ; Humans ; Influenza A Virus, H5N1 Subtype/*genetics/immunology ; Influenza A Virus, H9N2 Subtype/*genetics/immunology ; Influenza Vaccines/*genetics/metabolism ; Influenza in Birds/immunology/virology ; Influenza, Human/immunology/*prevention & control/virology ; Neuraminidase/genetics/metabolism ; Transgenes ; Vaccines, Attenuated/*genetics/metabolism ; Viral Proteins/genetics/metabolism

In order to control the H9N2 subtype low pathogenic avian influenza (LPAI), an inactivated vaccine has been used in Korea since 2007. The Korean veterinary authority permitted the use of a single H9N2 LPAI vaccine strain to simplify the evolution of the circulating virus due to the immune pressure caused by the vaccine use. It is therefore important to determine the suitability of the vaccine strain in the final inactivated oil emulsion LPAI vaccine. In this study, we applied molecular rather than biological methods to verify the suitability of the vaccine strain used in commercial vaccines and successfully identified the strain by comparing the nucleotide sequences of the hemagglutinin and neuraminidase genes with that of the permitted Korean LPAI vaccine strain. It is thought that the method used in this study might be successfully applied to other viral genes of the LPAI vaccine strain and perhaps to other veterinary oil emulsion vaccines.
Animals ; Base Sequence ; Birds ; DNA, Viral/chemistry/genetics ; Hemagglutinin Glycoproteins, Influenza Virus/chemistry/genetics ; Influenza A Virus, H9N2 Subtype/genetics/*immunology ; Influenza Vaccines/genetics/*immunology ; Influenza in Birds/*immunology/prevention & control/virology ; Molecular Sequence Data ; Neuraminidase/chemistry/genetics ; Polymerase Chain Reaction/veterinary ; Republic of Korea ; Sequence Alignment ; Vaccines, Inactivated/genetics/immunology

The hemagglutinin (HA) gene from H5N1 avian influenza virus and the chicken interleukin 2 (chiIL-2) gene were inserted into a expressing vector p12LS to construct a recombinant transferring vector p12LSH5AIL2, in which HA gene under the control of the promoter Ps was in inverse tandem connection with the chiIL-2 gene under the control of the promoter PE/L. The p12LSH5AIL2 was then used to transfect the chicken embryo fibroblasts (CEF) pre-infected with a wild-type fowlpox virus 282E4 strain, to generate a recombinant fowlpox virus coexpressing the inserted HA and chiIL2 genes (rFPV-H5AIL2). The rFPV-H5AIL2 was obtained and purified by blue plaque screening on the CEF. The in vitro expression of HA gene by rFPV-H5AIL2 was detected in the recombinant fowlpox virus-infected CEFs with an indirect immunofluorescence assay, and the expression of the chiIL2 gene by rFPV-H5AIL2 was confirmed by detection of the chiIL2 mRNA by RT-PCR and by detection of chiIL2 by the indirect immunofluorescence assay. Experiments on SPF and commercial chickens demonstrated that the titer for HI antibodies induced by the rFPV-H5AIL2 was significantly higher than that by the rFPV-HA. The group immunized with the rFPV-H5AIL2 exhibited the similar ratios of protective efficacy and virus shedding as the group immunized with the rFPV-HA in SPF chicken. However, in commercial chicken, the group immunized with the rFPV-H5AIL2 generated significantly higher protection against H5N1 avian influenza virus challenge and lower virus shedding than the group immunized with the rFPV-HA. This study paved the way for further development of a new AIV recombinant vaccine.
Animals ; Cells, Cultured ; Chick Embryo ; Chickens ; Fowlpox virus ; genetics ; metabolism ; Gene Expression ; Genetic Engineering ; Genetic Vectors ; genetics ; metabolism ; Hemagglutinins ; genetics ; immunology ; Influenza A Virus, H5N1 Subtype ; genetics ; immunology ; Influenza in Birds ; immunology ; virology ; Interleukin-2 ; genetics ; immunology ; Random Allocation

To construct Fv antibodies against H5N1 Avian influenza virus hemagglutinin,extracted mRNA from B lymphoblastoid cell lines secreting anti-HA antibodies was used and the VH and VL genes were amplified by RT-PCR and linked together by splicing overlap extension (SOE) with (Gly4 Ser)3 linker. The recombinant plasmid was then transformed to E. coli BL21(DE3) and sequence analysis indicated the total length of scFv was 714 bp and the expression of Fv was validated by PAGE and Western blot.
Animals ; Antibodies ; genetics ; metabolism ; pharmacology ; Birds ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Gene Expression Regulation ; Hemagglutinins ; immunology ; Immunoglobulin Heavy Chains ; genetics ; Immunoglobulin Light Chains ; genetics ; Immunoglobulin Variable Region ; genetics ; metabolism ; Influenza A Virus, H5N1 Subtype ; drug effects ; immunology ; Influenza in Birds ; virology ; Mice ; Mice, Inbred BALB C ; Recombinant Fusion Proteins ; genetics ; metabolism ; pharmacology ; Reverse Transcriptase Polymerase Chain Reaction ; Viral Proteins ; immunology