H9N2 influenza viruses have been circulating worldwide in multiple avian species and have repeatedly infected humans to cause typical disease. The continued avian-to-human interspecies transmission of H9N2 viruses raises concerns about the possibility of viral adaption with increased virulence for humans. To investigate the genetic basis of H9N2 influenza virus host range and pathogenicity in m...

Bacterial co-infections can probably influence the pathogenicity of H9N2 low pathogenic avian influenza virus (AIV). This study aimed to evaluate the effect of exposure time to Escherichia coli (O:2) on the pathogenicity of H9N2 AIV in broiler chickens. Three hundred and sixty broiler chickens were randomly allocated to six equal groups. At the age of 26 days, all chicks except groups 5 and 6 w...

sixteen avian influenza (ai) h9n2 viruses were isolated from disease outbreaks in different parts of iranduring (1998–2001). these ai isolates were used for pathogenicity, haemagglutinin (ha) gene variation andphylogenetic analysis. results in both pathogenicity tests and ha gene cleavage site sequence detectionrepresented a non-highly pathogenic feature for all iranian ai isolates studied. the...

We isolated a strain of H9N2 avian influenza virus from a quail in southern China in May 2015 and named it A/quail/Guangxi/198Q39/2015. All eight gene segments of the strain were sequenced. Sequence analysis indicated that the amino acid motif of the hemagglutinin cleavage site of this H9N2 virus was RSSR↓GLF, which is a typical characteristic of the low pathogenic avian influenza virus. This s...

In 1997, an H5N1 avian influenza A/Hong Kong/156/97 virus transmitted directly to humans and killed six of the 18 people infected. In 1999, another avian A/Hong/1074/99 (H9N2) virus caused influenza in two children. In such cases in which vaccines are unavailable, antiviral drugs are crucial for prophylaxis and therapy. Here we demonstrate the efficacy of the neuraminidase inhibitor GS4104 (ose...

We report here the genomic sequence of an H9N2 influenza A virus [A/greater white-fronted goose/Alaska/81081/2008 (H9N2)]. This virus shares ≥99.8% identity with a previously reported virus. Both strains contain a G590S mutation in the polymerase basic 2 (PB2) gene, which is a pathogenicity marker in the pandemic 2009 H1N1 virus when combined with R591.

The H9N2 subtype influenza virus (IV) is a remarkable member of the influenza A viruses because it can infect not only chickens, ducks and pigs, but also humans. Pigs are susceptible to both human and avian influenza viruses and have been proposed to be intermediate hosts for the generation of pandemic influenza viruses through reassortment or adaptation to the mammalian host. To further unders...

avian influenza is an important disease of poultry with the potential to cause major epidemics resulting in significant economic losses. the presence of avian influenza viruses (aiv) in chickens in iran has not been previously reported. an avian influenza outbreak in broiler, layer and breeder farms occurred during a very hot summer in july 1998. three aiv isolates designated as 101, 102 and 10...

In 2009, a novel H1N1 influenza (pH1N1) virus caused the first influenza pandemic in 40 y. The virus was identified as a triple reassortant between avian, swine, and human influenza viruses, highlighting the importance of reassortment in the generation of viruses with pandemic potential. Previously, we showed that a reassortant virus composed of wild-type avian H9N2 surface genes in a seasonal ...