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H9N2 influenza viruses have been circulating in China since 1994, but a systematic investigation of H9N2 in northern China has not been undertaken since 2004. Here, using the sequences of 22 viruses we isolated from poultry and pigs in northern China during 2003-2008, in combination with sequences available in a public database, we analyzed the evolution of(More)
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(More)
Evidence of H1N1/2009 influenza virus infection was identified in two domestic dogs in China in November 2009. Virus isolation and sequence analysis of all eight genes of the two isolates showed that they were related closely to the H1N1/2009 influenza virus circulating in humans, indicating that they were probably acquired from humans. To determine the(More)
To determine risk for avian influenza virus infection, we conducted serologic surveillance for H5 and H9 subtypes among poultry workers in Beijing, China, 2009-2010, and assessed workers' understanding of avian influenza. We found that poultry workers had considerable risk for infection with H9 subtypes. Increasing their knowledge could prevent future(More)
The emergence of human infection with a novel H7N9 influenza virus in China raises a pandemic concern. Chicken H9N2 viruses provided all six of the novel reassortant's internal genes. However, it is not fully understood how the prevalence and evolution of these H9N2 chicken viruses facilitated the genesis of the novel H7N9 viruses. Here we show that over(More)
Twelve avian-origin H3N2 influenza strains were isolated from dogs with signs of respiratory disease in northern China during 2009-2010. Phylogenetic analysis showed that eight gene segments of all the isolates had a close relationship with those of avian-origin H3N2 canine influenza viruses (CIVs) from South Korea and southern China. Genetic analysis(More)
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(More)
H9N2 influenza viruses have been circulating worldwide in multiple avian species and repeatedly infecting mammals, including pigs and humans, posing a significant threat to public health. The coexistence of H9N2 and pandemic influenza H1N1/2009 viruses in pigs and humans provides an opportunity for these viruses to reassort. To evaluate the potential public(More)
We examined the molecular basis of virulence of pandemic H1N1/09 influenza viruses by reverse genetics based on two H1N1/09 virus isolates (A/California/04/2009 [CA04] and A/swine/Shandong/731/2009 [SD731]) with contrasting pathogenicities in mice. We found that four amino acid mutations (P224S in the PA protein [PA-P224S], PB2-T588I, NA-V106I, and(More)