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From April to September 2012, periodic surveillance of avian influenza H5N1 viruses from different wild bird species was conducted in Northeast China. Three highly pathogenic avian influenza (HPAI) H5N1 viruses were isolated from a yellow-browed warbler, common shoveler, and mallard. To trace the genetic lineage of the isolates, nucleotide sequences of all eight gene segments were determined and phylogenetically analyzed. The data indicated that three viruses belonged to the same antigenic virus group: clade 2.3.2.1. To investigate the pathogenicity of these three viruses in different hosts, chickens, ducks, and mice were inoculated. The results showed that chickens were susceptible to each of the three HPAI H5N1 viruses, resulting in 100% mortality within 2-6 days after infection, whereas the three isolates exhibited distinctly different virulence in ducks and mice. The results of this study demonstrated that HPAI H5N1 viruses of clade 2.3.2.1 are still circulating in wild birds through overlapping migratory flyways. Therefore, continuous monitoring of H5N1 in both domestic and wild birds is necessary to prevent a potentially wider outbreak., (Copyright © 2014 Elsevier B.V. All rights reserved.)

To explore the ecology of the H6 subtype avian influenza viruses in Hebei Province, China, a long-term surveillance was conducted in 2012 among domestic poultry and birds in a wildlife park. In this study, we report the characterization of a novel H6N6 avian influenza virus isolated from a healthy green peafowl in Qinghuangdao Wildlife Park in 2012. A phylogenetic analysis indicated that the isolated H6N6 strain has the same gene constellation as the ST3367-like strains, which are mainly distributed in southern and eastern China. A mouse experiment showed that the isolate replicated efficiently in the lungs and turbinates of infected mice without previous adaptation, resulting in locally thickened alveolar septa and interstitial pneumonia. Further studies of the H6 subtype viruses are required to clarify their evolutionary pattern in north China, which will benefit disease control and pandemic preparedness for novel viruses., (Copyright © 2014 Elsevier B.V. All rights reserved.)