Animals ; Birds ; Humans ; Influenza A virus ; genetics ; metabolism ; pathogenicity ; Influenza in Birds ; metabolism ; virology ; Influenza, Human ; metabolism ; virology ; Viral Nonstructural Proteins ; genetics ; metabolism ; Virulence

The expression of the hemagglutinins of Avian influenza virus H5 H7and H9 subtypes was studied in this article by Pichia pastoris, one of the eukaryotis expression systems. Three reconstructed expression plasmids and engineering strains, named pPIC9K-H5HA, pPIC9K-H7HA, pPIC9K-H9HA and GS115/pPIC9K-H5HA, GS115/pPIC9K-H7HA, GS115/pPIC9K-H9HA repectively, were obtained. The reconstructed yeast engineering strains were identified by MD and MM plate selecting and PCR. The induced interests proteins were examined by SDS-PAGE and Western-bloting,the results showed that the interest genes were expressed exactly. And this will be helpful in the future study of antigen detection and antibody detection kit, as well in the subunit vaccines developing.
Animals ; Hemagglutinin Glycoproteins, Influenza Virus ; biosynthesis ; genetics ; Influenza A Virus, H5N1 Subtype ; genetics ; Influenza A Virus, H7N7 Subtype ; genetics ; Influenza A Virus, H9N2 Subtype ; genetics ; Pichia ; genetics ; metabolism

Disaster Planning ; Disease Outbreaks ; Humans ; Influenza A Virus, H1N1 Subtype ; metabolism ; Influenza, Human ; epidemiology ; transmission ; Travel

As part of our ongoing influenza surveillance program in South China, 19 field strains of H9N2 subtype avian influenza viruses (AIVs) were isolated from dead or diseased chicken flocks in Guangdong province, South China, between 2012 and 2013. Hemagglutinin (HA) genes of these strains were sequenced and analyzed and phylogenic analysis showed that 12 of the 19 isolates belonged to the lineage h9.4.2.5, while the other seven belonged to h9.4.2.6. Specifically, we found that all of the viruses isolated in 2013 belonged to lineage h9.4.2.5. The lineage h9.4.2.5 viruses contained a PSRSSRdownward arrowGLF motif at HA cleavage site, while the lineage h9.4.2.6 viruses contained a PARSSRdownward arrowGLF at the same position. Most of the isolates in lineage h9.4.2.5 lost one potential glycosylation site at residues 200-202, and had an additional one at residues 295-297 in HA1. Notably, 19 isolates had an amino acid exchange (Q226L) in the receptor binding site, which indicated that the viruses had potential affinity of binding to human like receptor. The present study shows the importance of continuing surveillance of new H9N2 strains to better prepare for the next epidemic or pandemic outbreak of H9N2 AIV infections in chicken flocks.
Animals ; *Chickens ; China ; Hemagglutinin Glycoproteins, Influenza Virus/chemistry/*genetics/metabolism ; Influenza A Virus, H9N2 Subtype/*genetics/metabolism ; Influenza in Birds/virology ; Phylogeny ; Poultry Diseases/*virology ; Sequence Analysis, RNA/veterinary

Influenza B virus is one of the causes for seasonal influenza, which can account for serious illness or even death in some cases. We tested the expression of extracellular domain of hemagglutinin (HA-ecto) of influenza B viruses in mammalian cells, and then determined the immunogenicity of HA-ecto in mice. The gene sequence encoding influenza B virus HA-ecto, foldon sequence, and HIS tag was optimized and inserted into pCAGGS vector. The opening reading frame (ORF) of neuraminidase was also cloned into pCAGGS. The pCAGGS-HA-ecto and pCAGGS-NA were co-transfected into 293T cells using linear polyethylenimine. Cell supernatant after transfection was collected after 96 h, and the secreted trimmeric HA-ecto protein was purified by nickel ion affinity chromatography and size exclusion chromatography. Subsequently, the mice were immunized with HA-ecto protein, and the corresponding antibody titers were detected by ELISA and hemagglutination inhibition (HAI) assays. The results showed that soluble trimeric HA-ecto protein could be obtained using mammalian cell expression system. Moreover, trimeric HA-ecto protein, in combination with the adjuvant, induced high levels of ELISA and HAI antibodies against homogenous and heterologous antigens in mice. Thus, the soluble HA-ecto protein expressed in mammalian cells could be used as a recombinant subunit vaccine candidate for influenza B virus.
Animals ; Hemagglutinin Glycoproteins, Influenza Virus/genetics* ; Hemagglutinins/genetics* ; Influenza B virus/metabolism* ; Influenza Vaccines/genetics* ; Mammals/metabolism* ; Mice ; Mice, Inbred BALB C

Influenza poses a great threat to life and health in populations worldwide. Studies regarding the protein components of influenza viruses will facilitate the research and development of vaccines and diag nostic reagents. The influenza virus contains both structural and non-structural proteins. From the outset, it has been accepted that an influenza A virus possesses eight gene segments that encode eight corresponding viral proteins, respectively. Research has demonstrated that the M gene encodes the M2 ion channe! protein and the NS gene encodes the non-structural protein, NS2. In recent years, several novel viral proteins have been identified from influenza A viruses. This article will briefly describe the state of current research into PA-related proteins of influenza A viruses.
Animals ; Humans ; Influenza A virus ; enzymology ; genetics ; Influenza, Human ; virology ; RNA Replicase ; genetics ; metabolism ; Viral Proteins ; genetics ; metabolism

BACKGROUNDPB1-F2 protein has been proven to increase the pathogenicity of influenza A virus (IAV) strains in primary infection and in secondary bacterial infection. It can also regulate the activity of viral polymerase. However, it was shown in another retrospective study that a portion of IAVs do not express full-length PB1-F2 protein during virus development; different kinds of stop codons cause exits in the open reading frames and form PB1-F2 gene products with the corresponding genotypes. Truncated PB1-F2 in human H3N2 IAVs has long been detected in North America but its evolution in China is still unclear.

METHODSInfluenza-like illnesses (ILIs) from the whole of Jiangsu Province were collected and inspected to determine the type and subtype of the viruses. A portion of isolates collected in the epidemic period were selected as samples for later whole-genome sequencing, and the exact sequences were determined and analyzed.

RESULTSH3N2 influenza virus was one of the epidemical strains which had been prevalent during 2009-2010, in Jiangsu. Five H3N2 isolates with truncated PB1-F2 protein (25aa) were detected in influenza samples from Nanjing and Xuzhou, while seven similar H3N2 isolates were also reported in Niigata, Japan.

CONCLUSIONThis emergence indicates the possibility that there has been transmission of the H3N2 virus between the two countries.

China ; epidemiology ; Humans ; Influenza A Virus, H3N2 Subtype ; genetics ; metabolism ; Influenza, Human ; virology ; Viral Proteins ; chemistry ; genetics ; metabolism

Since March 2009, pandemic A/H1N1/2009 influenza virus has been spreading throughout many countries including China. The emerged virus caused great harm to human health and social economy. Hemagglutinin (HA) is the most important viral surface glycoprotein, mainly possessing three kinds of functions: (1) binding to host cell receptor, (2) triggering the fusion between viral envelop and target cell membrane, (3) stimulating the body to generate the neutralizing antibody. Advances in the structure, primary function, evolution and antigenicity of pandemic A/H1N1/2009 influenza virus HA protein are reviewed in this paper.
Animals ; Evolution, Molecular ; Hemagglutinin Glycoproteins, Influenza Virus ; chemistry ; genetics ; immunology ; metabolism ; Humans ; Influenza A Virus, H1N1 Subtype ; genetics ; immunology ; pathogenicity ; physiology ; Influenza, Human ; epidemiology ; virology ; Pandemics

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

HA and M2 genes derived from human highly pathogenic avian influenza H5N1 virus (A/Anhui/ 1/2005) isolated from China, were amplified and cloned into the DNA vaccine expression vector pVRC. In order to improve the expression of hemagglutinin, the human codon usage preference was made and the whole length of HA gene of H5NI (A/Anhui/1/2005) influenza virus was synthesized,named HA/YH/K, and inserted to pVRC vector, the expression of HA/YH/K protein in eukaryotic cells was significantly improved according to internal control of actin protein. Furthermore, the M2 and HA/YH/K genes were cloned into bicistronic eukaryotic expressing vector pIRES to yield the recombinant plasmid pIRES-HA/ YH/K-M2/YS/K, which could expressed HA and M2 protein simultaneously by transfection of one plasmid. Western blot and IFA showed that the recombinant pIRES-HA/YH/K-M2/YS/K plasmid was successfully expressed in several mammalian cells (Hela, MDCK and 293FT). The above results may help to identify the function and pathogenic mechanism of HA, M2 genes derived from HPAI H5N1 (Anhui strain) and pave a way for the development of novel bivalent vaccines against human highly pathogenic avian influenza virus and for preparedness for influenza pandemic.
Animals ; Cell Line ; Gene Expression ; Genetic Engineering ; Genetic Vectors ; genetics ; metabolism ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; metabolism ; Humans ; Influenza A Virus, H5N1 Subtype ; genetics ; isolation & purification ; metabolism ; Influenza, Human ; virology ; Recombinant Fusion Proteins ; genetics ; metabolism ; Viral Matrix Proteins ; genetics ; metabolism