Characterization of H9N2 influenza viruses isolated from vaccinated flocks in an integrated broiler chicken operation in eastern China during a 5 year period (1998–2002)

Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, Yangzhou 225009, PR China.
Journal of General Virology (Impact Factor: 3.18). 01/2009; 89(Pt 12):3102-12. DOI: 10.1099/vir.0.2008/005652-0
Source: PubMed


In the current study, we characterized H9N2 influenza viruses isolated from vaccinated flocks in an integrated broiler chicken operation during a 5 year period (1998-2002). Phylogenetic analysis of the 8 genes of 11 representative viruses showed that they all shared high similarity to that of the first isolate, A/Chicken/Shanghai/F/1998 (Ck/SH/F/98), and clustered to the same lineages. Furthermore, all 11 viruses had a 9 nt deletion between positions 206 and 214 of the neuraminidase gene. These genetic characteristics strongly suggest that these viruses are descendants of the first isolate. In addition, our study also showed that the H9N2 viruses circulating in the operation during this 5 year period were evolving, as shown by antigenic variations between viruses manifested by reactivity with polyclonal antisera and monoclonal antibodies, by haemagglutination with erythrocytes from different animals, by amino acid differences in haemagglutinin and neuraminidase proteins, and by variation in their ability to replicate in the respiratory and intestinal tract and to be transmitted by aerosol. Phylogenetic analysis revealed that the internal genes from some H5N1 viruses of duck origin clustered together with those from H9N2 virus and that the RNP genes of these H5N1 viruses isolated after 2001 are more closely related to the genes of the Ck/SH/F/98-like H9N2 viruses, indicating more recent reassortment events between these two subtypes of viruses. Continuous surveillance of influenza virus in poultry and waterfowl is critical for monitoring the genesis and emergence of potentially pandemic strains in this region.

Download full-text


Available from: Shan Lu
  • Source

    Full-text · Article ·
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Many novel reassortant influenza viruses of the H9N2 genotype have emerged in aquatic birds in southern China since their initial isolation in this region in 1994. However, the genesis and evolution of H9N2 viruses in poultry in eastern China have not been investigated systematically. In the current study, H9N2 influenza viruses isolated from poultry in eastern China during the past 10 years were characterized genetically and antigenically. Phylogenetic analysis revealed that these H9N2 viruses have undergone extensive reassortment to generate multiple novel genotypes, including four genotypes (J, F, K, and L) that have never been recognized before. The major H9N2 influenza viruses represented by A/Chicken/Beijing/1/1994 (Ck/BJ/1/94)-like viruses circulating in poultry in eastern China before 1998 have been gradually replaced by A/Chicken/Shanghai/F/1998 (Ck/SH/F/98)-like viruses, which have a genotype different from that of viruses isolated in southern China. The similarity of the internal genes of these H9N2 viruses to those of the H5N1 influenza viruses isolated from 2001 onwards suggests that the Ck/SH/F/98-like virus may have been the donor of internal genes of human and poultry H5N1 influenza viruses circulating in Eurasia. Experimental studies showed that some of these H9N2 viruses could be efficiently transmitted by the respiratory tract in chicken flocks. Our study provides new insight into the genesis and evolution of H9N2 influenza viruses and supports the notion that some of these viruses may have been the donors of internal genes found in H5N1 viruses.
    Full-text · Article · Jul 2009 · Journal of Virology
  • [Show abstract] [Hide abstract]
    ABSTRACT:   The geographic extent, xenospecificity, and clinical course of influenza A (H5N1), the bird flu strain, suggest the virus is an excellent candidate for a pandemic infection. Much attention has been paid to the virus's virology, pathogenesis and spread. In contrast, little effort has been aimed at identifying influenza's social origins. In this article, I review H5N1's phylogeographic properties, including mechanisms for its evolving virulence. The novel contribution here is the attempt to integrate these with the political economies of agribusiness and global finance. Particular effort is made to explain why H5N1 emerged in southern China in 1997. It appears the region's reservoir of near-human-specific recombinants was subjected to a phase change in opportunity structure brought about by China's newly liberalized economy. Influenza, 200 nm long, seems able to integrate selection pressures imposed by human production across continental distances, an integration any analysis of the virus should assimilate in turn.
    No preview · Article · Oct 2009 · Antipode
Show more