|Huynh, Lien P|
|Hguyen, Hanh H|
Submitted to: Journal of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/12/2004
Publication Date: 4/5/2005
Citation: Nguyen, D.C., Uyeki, T.M., Jadhao, S., Maines, T., Shaw, M., Matsuoka, Y., Rowe, T., Lu, X., Hall, H., Balish, A., Klimov, A., Tumpey, T., Swayne, D.E., Huynh, L.T., Nghiem, H.K., Hguyen, H.T., Hoang, L.T., Cox, N.J., Katz, J.M. 2005. Isolation and characterization of avian influenza viruses, including highly pathogenic h5n1 viruses, from poultry in live bird markets in hanoi, vietnam - 2001. Journal of Virology, p.4201-4212. Interpretive Summary: Avian influenza viruses have crossed from birds to humans causing infections and deaths in Asia. This study determined that avian influenza viruses were present in ducks and geese in the Live Poultry Markets of Vietnam in 2001. The deadly H5N1 viruses were found. In experimental studies, these viruses were lethal to chickens but not for ducks, geese or mice. This indicates the H5N1 viruses were present in Vietnam three years before the large outbreaks of 2004, and they had negative impact on agriculture.
Technical Abstract: Since 1997, outbreaks of highly pathogenic H5N1 and circulation of H9N2 viruses among domestic poultry in Asia have posed a threat to public health. To better understand the extent of transmission of avian influenza viruses (AIV) to humans in Asia, we conducted a cross-sectional virologic study in live bird markets (LBM) in Hanoi, Vietnam in October 2001 as part of a sero-epidemiological investigation on AIV infection among poultry workers that will be reported separately. Specimens from 189 birds and 18 environmental samples were collected at 10 LBM. Four influenza A viruses of the H4N6 (n=1), H5N2 (n=1), and H9N3 (n=2) subtypes were isolated from healthy ducks for an isolation rate of over 30% from this species. The hemagglutinin (HA) gene of the H4N6 virus shared the greatest nucleotide sequence homology (89.9%) with the HA of A/Duck/Czechoslovakia/1/56. The HA genes of the 2 H9N3 viruses were genetically and antigenically similar to Korea group of H9 viruses such as A/Duck/Hokkaido/9/99. The HA gene of the H5N2 virus was antigenically and genetically most similar to earlier H5 viruses like A/Chicken/Italy/312/97. Two H5N1 viruses were isolated from healthy geese. The HA of these viruses possessed multiple basic amino acids motifs at the HA cleavage site, were highly pathogenic for experimentally infected chickens, and were thus characterized as highly pathogenic (HP) AIV. The HA genes of these viruses shared high amino acid homologies with those of other H5N1 viruses isolated during this period, but were antigenically and genetically distinct from H5N1 viruses isolated from poultry and humans in Vietnam during the early 2004 outbreaks. The HP H5N1 viruses isolated from Hanoi LBM in 2001 were not highly virulent for experimentally infected ducks, mice or ferrets. These results establish that HP H5N1 viruses with properties similar to viruses isolated in Hong Kong and mainland China during this period circulated in LBM in North Vietnam as early as 2001, suggest a common source for H5N1 viruses circulating in these Asian countries, and provide a framework to better understand the recent widespread emergence of HP H5N1 viruses in Asia.