Study Explains Genetic Changes in H6 Bird Flu Virus

US - Researchers in California have found evidence that there has been mixing of the genetic material between the Eurasian and North American 'families' of the H6 sub-type of the avian flu virus.
calendar icon 29 June 2009
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From the University of California School of Veterinary Medicine, Davis and National Center for Medical Intelligence, zu Dohna and colleagues have investigated the origins of the Eurasian and North American 'families' of the H6 subtype of the avian influenza virus (AIV). Previously thought to be distinct families as the migratory pathways of birds do not generally overlap, this latest study suggests that the genes have moved between the hemispheres.

In the introduction to their paper published in the current issue of Emerging Infectious Diseases, zu Dohna and co-authors explain that the spread of highly pathogenic avian influenza virus (AIV) (H5N1) underlines the potential for global AIV movement through birds.

They continue that the phylogenies of AIV genes from avian hosts usually separate into Eurasian and North American clades, reflecting limited bird migration between the hemispheres. However, mounting evidence that some H6 sequences from North America cluster with Eurasian sub-type H6 sequences calls the strict hemispheric divide into question.

The researchers conducted a comprehensive phylogenetic analysis of the extent and timing of cross-hemisphere movements by the H6 gene.

Their results suggested that Eurasian H6 subtype has invaded North America several times, with the first invasions occurring 10 years before the first detection of invading isolates. The members of the North American clade decreased from 100 per cent in the 1980s to 20 per cent in the 2000s among H6 isolates from North America.

The authors conclude that unraveling the reasons for this large-scale gene movement between hemispheres might identify drivers of global AIV circulation.


zu Dohna H., J. Li, C.J. Cardona, J. Miller and T.E. Carpenter. 2009. Invasions by Eurasian avian influenza virus H6 genes and replacement of the virus' North American clade. Emerging Infectious Disseases, July 2009. DOI: 10.3201/eid1507.090245

Further Reading

- You can view the full report by clicking here.

Further Reading

- You can visit the Avian Flu page by clicking here.
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