To investigate the susceptibility of Chukars to duck avian influenza virus H9N2 and explore their role in interspecies transmission of influenza viruses. Chukars were inoculated with duck avian influenza viruses H9N2. The present study demonstrated that inflammatory lesions and virus antigen were present in the trachea, bronchus, and parabronchus, and the viruses could be isolated from throat swabs and lung tissue homogenate supernatants. At 14 d post virus inoculation, anti-H9 influenza virus antibody in the serum was detected. The results indicated that Chukars are susceptible to duck avian influenza virus and serve as an intermediate host, thereby facilitating viral gene evolution and supporting the need for continued surveillance of epidemiology and evolution of the influenza virus in Chukars.
Animals ; Galliformes ; Influenza A Virus, H9N2 Subtype ; pathogenicity ; physiology ; Influenza in Birds ; virology ; Respiratory System ; pathology ; virology ; Virus Replication ; physiology

Two H5N1 avian influenza viruses (AIV), A/mallard/Huadong/S/2005 (S, IVPI = 2.65, in mallard) and A/mallard/Huadong/Y/2003 (Y, IVPI = 0, in mallard), were capable of distinct in pathogenicity to non-immunized mallards (Anas platyrhynchos). There were two amino acid residues difference in the HA cleavage site between two viruses, 322 (S, Leu; Y, Gln) and 329 (S, deletion; Y, Lys). Based on the variation, a series of recombinant viruses carrying HA gene either from S or Y virus with mutation at 322 and/or 329 were constructed via reverse genetics system to explore the influence of the two amino acid residues on viral pathogenicity in mallards. Recombinant viruses with S virus backbone were completely attenuated in terms of their virulence to ducks when position 322 (L322Q) and/or position 329 (-329K) of HA gene had been mutated. The critical role that L322 and -329 of HA protein from S virus play in the high virulence to ducks were influenced by the entire background of that protein because the recombinant virus with HA gene from Y and other seven genes from S were completely attenuated even if Q322L and K329- mutations of HA gene had been achieved. Recombinant viruses with Y virus backbone significantly increased their virulence to ducks when position 322 (Q322L) and/or position 329 (K329-) of HA gene had been mutated. All recombinant viruses carrying HA gene from Y with Q322L and/or K329-mutations and other seven genes from S were completely attenuated in terms of virulence to ducks whereas all recombinant viruses carrying HA gene from Y with same mutations and other seven genes from Y gained significant virulence. It seems that the compatibility among eight genes might be an important factor for HA to exert its functions. Results indicated that the mutation at amino acid position 322 and deletion at 329 in HA cleavage site significantly influence the pathogenicity of S and Y viruses in mallard, the compatibility among eight genes also contribute to the pathogenicity of both viruses in mallard.
Animals ; Birds ; Hemagglutinin Glycoproteins, Influenza Virus ; chemistry ; genetics ; physiology ; Influenza A Virus, H5N1 Subtype ; genetics ; pathogenicity ; Structure-Activity Relationship ; Virulence

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

BACKGROUNDThe duration of viral shedding and the transmission of 2009 H1N1 influenza among individuals, especially among the younger population with mild illness, are not well understood now. The aim of this study was to determine the viral shedding of the young adult patients with mild 2009 H1N1 influenza in China.

METHODSFrom September 2009 to January 2010, the clinical data and serial nasopharyngeal swabs of 67 patients with 2009 H1N1 influenza and 37 patients with seasonal influenza aged from 18 years to 35 years were collected. The nasopharyngeal swab samples were detected by real time RT-PCR to determine the viral shedding. All the patients did not receive the antiviral therapy but Chinese medicine for detoxicating.

RESULTSAmong the patients with H1N1 virus infection, 82.1% (55/67) patients presented with fever symptom, while more patients with high fever (≥ 39°C) were found in seasonal influenza patients (P < 0.05). For the H1N1 patients, the median interval between the symptom onset and the undetectable RNA was six days (4 - 10 days). But viral shedding was still found in 31.3% patients after 7 days following illness onset. The median interval between disappearance of fever and an undetectable viral RNA level was three days (2 - 8 days), and 17.9% patients were found to be viral shedding 6 days later after normalization of body temperature. For the seasonal influenza patients, 94.6% patients were detected out viral RNA within 7 days. The median interval of seasonal influenza between the symptom onset and the undetectable RNA was four days (3 - 8 days). The median interval between disappearance of fever and an undetectable viral RNA level was three days (2 - 6 days).

CONCLUSIONIt suggests that 7 days isolation period from the illness onset or 24 hours after the resolution of fever and respiratory symptoms are not long enough to cut off the transmission among Chinese young adults with mild illness.

Adult ; Female ; Humans ; Influenza A Virus, H1N1 Subtype ; genetics ; pathogenicity ; Influenza, Human ; epidemiology ; virology ; Male ; Real-Time Polymerase Chain Reaction ; Virus Shedding ; genetics ; physiology ; Young Adult

In 2014, two genetically distinct H5N8 highly pathogenic avian influenza (HPAI) viruses were isolated from poultry and wild birds in Korea. The intravenous pathogenicity indices for the two representative viruses were both 3.0. Mortality of chickens intranasally inoculated with the two H5N8 viruses was 100% with a mean death times of 2.5 and 4.5 days. Mortality rates of the contact groups for the two H5N8 viruses were 33.3% and 66.6%. Our study showed that transmissibility of the novel H5N8 viruses was different from that of previously identified H5N1 HPAI viruses, possibly due to genetic changes.
Animals ; Chickens ; Disease Outbreaks/veterinary ; Influenza A virus/*pathogenicity/*physiology ; Influenza in Birds/*mortality/transmission/virology ; Poultry Diseases/*mortality/transmission/virology ; Republic of Korea/epidemiology ; Virulence

Eleven proteins encoded by influenza A viruses play different roles in host receptor recognition, cross-species transmission, virus replication, pathogenicity, and induction of host immune responses. Understanding of the pathogenic mechanism of mutations in influenza A virus-encoded proteins could offer new targets for the development of universal vaccines and effective drugs against highly pathogenic influenza viruses. Based mainly on the current literature, this article is intended to provide a comprehensive analysis of progresses in amino acid variations in influenza A virus-encoded proteins and their relationships to pathogenicity as well as cross-species transmissibility.
Amino Acid Sequence ; Animals ; Genetic Variation ; Humans ; Influenza A virus ; genetics ; pathogenicity ; Influenza, Human ; transmission ; virology ; Mice ; Mutation ; Orthomyxoviridae Infections ; transmission ; virology ; Viral Proteins ; genetics ; physiology

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

Influenza virus assembly requires the completion of viral protein and vRNP transport to the assembly site at the plasma membrane. Therefore, efficient regulation of intracellular transport of the viral proteins and vRNPs to the surface of the host cell is especially important for virus morphogenesis. Influenza A virus uses the machineries of host cells to transport its own components including ribonucleoproteins (vRNPs) and three transmembrane proteins hemagglutinin (HA), neuraminidase (NA) and matrix 2 protein (M2). It has been shown that newly synthesized vRNPs are associated with active form of Rab11 and accumulate at recycling endosomes adjacent to the microtubule organizing center (MTOC) following nuclear export. Subsequently, they are transported along the microtubule network toward the plasma membranes in cargo vesicles. The viral transmembrane proteins are translated on the rough endoplasmic reticulum and transported to the virus assembly site at the plasma membrane. It has been found that several host factors such as ARHGAP21 and GTPase Cdc42 are involved in regulation of intracellular trafficking of influenza A virus transmembrane proteins including NA. In this review, we will highlight the current knowledge about anterograde transport and its regulation of the influenza A virus transmembrane proteins and genome in the host cytoplasm.
Cytoplasm ; metabolism ; GTP Phosphohydrolases ; metabolism ; GTPase-Activating Proteins ; metabolism ; Genome, Viral ; Hemagglutinin Glycoproteins, Influenza Virus ; metabolism ; Humans ; Influenza A virus ; genetics ; pathogenicity ; physiology ; Neuraminidase ; metabolism ; Protein Transport ; Ribonucleoproteins ; metabolism ; Viral Matrix Proteins ; metabolism ; cdc42 GTP-Binding Protein ; metabolism

The NS1 gene of the H5N1 subtype avian influenza virus was amplified by RT-PCR, and the am-plified product was cloned into the eukaryotic expression vector pCMV-Myc, then it was transfected into A549 cells. After 48 h, the expression of NS1 was detected by Western blot. Fluorescence and electron microscopy and flow cytometry showed that the NS1 gene of H5N1 avian influenza virus could induce apop-tosis in human pulmonary carcinoma cell line A549.
Annexin A5 ; analysis ; Apoptosis ; Cell Line, Tumor ; Cloning, Molecular ; Humans ; Influenza A Virus, H5N1 Subtype ; genetics ; pathogenicity ; Lung Neoplasms ; pathology ; Viral Nonstructural Proteins ; genetics ; physiology

As the scientific community scrambles to define the ancestry and lineages of the eight segments of new pandemic H1N1 strain, we looked for unique genetic events in this virus's genome to explain the newly found enhanced virulence and transmissibility among humans. Genome annotations of this virus identified a stop mutation replacing serine at codon 12 (S12Stop) of the PB1-F2 protein, a virulence factor in influenza A viruses. Here, we discuss the significance of this finding and how it may contribute to host specialization, explaining the virtual absence of the H1N1 influenza A virus strain in pig populations. This finding is expected to lead to a better understanding of the transmission and pathogenesis of the 2009 pandemic strain.
Amino Acid Sequence ; Gene Expression Regulation, Viral/physiology ; Host-Pathogen Interactions ; Humans ; Influenza A Virus, H1N1 Subtype/*genetics/*pathogenicity ; Influenza, Human/*virology ; Molecular Sequence Data ; Mutation ; Viral Proteins/chemistry/*genetics/metabolism ; Virulence