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Differential replication of avian influenza H9N2 viruses in human alveolar epithelial A549 cells

DOI: 10.1186/1743-422x-7-71

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Abstract:

Genetic characterization and phylogenetic analysis revealed that there are multiple lineages of H9N2 viruses isolated from various types of poultry including chickens, ducks, quail and pigeons. The H9N2 virus lineages found to be the most prevalent in poultry in southern China include the H9N2/G1-like lineage represented by A/Quail/Hong Kong/G1/97 (H9N2/G1) and the H9N2/Y280-like lineage represented by A/Duck/Hong Kong/Y280/97 (H9N2/Y280) and A/Chicken/Hong Kong/G9/97 (H9N2/G9) since 1997 [1]. These H9N2 lineages continued to disseminate in domestic poultry with the development of multiple reassortant subtypes from East Asia to the Middle East [2]. Additionally, avian-to-mammalian transmissions of H9N2 viruses were reported in Southeastern China [3].H9N2 viruses have repeatedly infected humans albeit causing a mild disease [3-5]. The low pathogenic H9N2 virus is widespread in poultry across Asia and Europe with ample opportunities for interaction with humans. It has caused infection in pigs (a putative mixing vessel for pandemic emergence) and causes severe disease in experimentally infected mice without prior adaptation [6]. The virus has an affinity for binding sialic acid receptors found on the human upper respiratory tract [7]. As past pandemics were not caused by highly pathogenic avian influenza viruses, the endemic of H9N2 viruses in poultry as well as their tropism for humans are at least as likely to cause the potential pandemic as the H5N1 virus, which is still the focus of attention [8]. Additionally, the H9N2/G1 viruses share six viral genes (viz. PB2, PB1, PA, NP, M and NS) with the lethal H5N1 viruses causing human disease in 1997 [1]. Furthermore, an H9N2 avian-human reassortant virus has been shown to have enhanced replication and efficient transmission in ferrets [9]. Thus H9N2 virus group is regarded by the World Health Organization as a potential pandemic candidate. Therefore we examined the replication characteristics of H9N2 virus lineages in th

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