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One of the highlights of my trip to Washington D.C. was being seated next to, and getting to know, Maggie Fox, Reuter's Health and Science Editor. She is one of a handful of really good reporters who cover avian influenza and was very kind to this humble blogger.
Here she writes on recent research that suggests the H5N1 virus originated in Southern China. By all means, follow the link to read the entire article.
Gene study suggests China source of H5N1 virus
Tue 18 Mar 2008, 19:27 GMT
WASHINGTON, March 18 (Reuters) - Southern China may have been the source for much of the spread of the H5N1 avian flu virus, researchers suggested on Tuesday.
A genetic analysis of the virus shows that strains that showed up in Vietnam, Thailand and Malaysia in 2002 and 2003 closely resemble a strain from poultry markets in China's Yunnan Province, the flu experts found.
Two viruses found in poultry in China's Hunan province in 2002 and 2003 were most closely related to viruses from Indonesia, they reported in the Journal of Virology.
"These results suggest a direct transmission link for H5N1 viruses between Yunnan and Vietnam and also between Hunan and Indonesia during 2002 and 2003," wrote the researchers, who included Guan Yi of the University of Hong Kong and Robert Webster of St. Jude Children's Research Hospital in Memphis, Tennessee.
The abstract for this study follows, published in the April 2008 edition of The Journal of Virology. (Reformatted for readability)
Identification of the Progenitors of Indonesian and Vietnamese Avian Influenza A (H5N1) Viruses from Southern China
J. Wang,1,2 D. Vijaykrishna,1,2 L. Duan,1,2 J. Bahl,1,2 J. X. Zhang,1,2 R. G. Webster,3 J. S. M. Peiris,2 H. Chen,1,2 Gavin J. D. Smith,1,2* and Y. Guan1,2*
Received 16 November 2007/ Accepted 16 January 2008
The transmission of highly pathogenic avian influenza H5N1 virus to Southeast Asian countries triggered the first major outbreak and transmission wave in late 2003, accelerating the pandemic threat to the world.
Due to the lack of influenza surveillance prior to these outbreaks, the genetic diversity and the transmission pathways of H5N1 viruses from this period remain undefined. To determine the possible source of the wave 1 H5N1 viruses, we recently conducted further sequencing and analysis of samples collected in live-poultry markets from Guangdong, Hunan, and Yunnan in southern China from 2001 to 2004.
Phylogenetic analysis of the hemagglutinin and neuraminidase genes of 73 H5N1 isolates from this period revealed a greater genetic diversity in southern China than previously reported. Moreover, results show that eight viruses isolated from Yunnan in 2002 and 2003 were most closely related to the clade 1 virus sublineage from Vietnam, Thailand, and Malaysia, while two viruses from Hunan in 2002 and 2003 were most closely related to viruses from Indonesia (clade 2.1).
Further phylogenetic analyses of the six internal genes showed that all 10 of those viruses maintained similar phylogenetic relationships as the surface genes. The 10 progenitor viruses were genotype Z and shared high similarity (
99%) with their corresponding descendant viruses in most gene segments. These results suggest a direct transmission link for H5N1 viruses between Yunnan and Vietnam and also between Hunan and Indonesia during 2002 and 2003.
Poultry trade may be responsible for virus introduction to Vietnam, while the transmission route from Hunan to Indonesia remains unclear.
While China has historically bristled at any suggestion that their nation might be the source of any infectious disease, including avian flu, the science continues to point in that direction.
