During the 1997 Hong Kong ‘bird flu’ incident, three subtypes of influenza
viruses, including H5N1, H9N2 and H6N1, were co-circulated at the live-poultry markets. Genetic analyses revealed that all these viruses shared the same internal gene complex and might have been all involved in generation of the HK/97-like H5N1 virus. Subsequent epidemiological and genetic studies found that both H6N1 and H9N2 viruses became established and prevalent in minor poultry in the region. However, the genesis pathway for each of these viruses has not been defined. It is also unclear about these three subtypes further interact with each other and evolve in the field, along with the emerging reassortant variants.
To address these questions, H6 subtype of avian influenza viruses isolated
from terrestrial minor poultry from 2000 to 2005, and from 2006 to 2007 in our
influenza surveillance in southern china has been genetically and antigenically
analyzed in this study. Genetic and phylogenetic analyses of representative strains indicated that all H6N1 isolates from 2000 to 2007 had W312-like hemagglutinin and neuraminidase genes. These H6N1 viruses have become established in the minor poultry, mainly in quail and chukar, in this region. However, phylogenetic analyses revealed that the internal genes of the H6N1 virus lineage were derived from multiple origins with different evolutionary pathways. Evolution analyses of different gene segments of H6N1 viruses revealed imbalance dynamic evolutionary rates between surface genes and internal genes, which suggests that this virus lineage was more likely a descendant of the HK/97-like H5N1, rather than its precursor virus.
Similar to what have been observed in the H5N1 and H9N2 virus lineages, the
internal gene complex of the H6N1 viruses was found to undergo extensive
reassortment. Many novel internal gene segments of H6N1 viruses were first
recognized in the reassortant H9N2 virus particles, suggesting that the gene flow is likely from H9N2 to H6N1. The co-circulation of different virus lineages in southern China has greatly increased the genetic diversity of influenza viruses in this region. Analyses of the dynamics of different H6N1 reassortant variants also showed that some of them became persistent, but others were transient in the field. The increasingly diversified H6N1 and other subtypes of viruses will naturally increase the opportunity of interspecies transmission and dissemination, and may pose renewal threat for public health. / published_or_final_version / Microbiology / Doctoral / Doctor of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174320 |
| Date | January 2011 |
| Creators | Cheung, Chung-lam., 張仲林. |
| Contributors | Chen, H, Guan, Y |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47158311 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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