Interactive map aids in tracking avian flu Technology could help forecast disease's spread Interactive map aids in tracking avian flu
From AScribe Newswire
Published: May 1, 2007
BOULDER, Colo — An interactive "supermap” that portrays the mutations and spread of the avian flu around the globe over time should help researchers and policy makers better understand the virus and anticipate outbreaks, a study involving University of Colorado at researchers said.
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The research team used data from the known evolution and spread of the avian flu, known as H5N1, to create a road map of viral spread in time and space, said CU ecology and evolutionary biology Assistant Professor Robert Guralnick, a study co-author. The team projected genetic and geographic information onto an interactive globe using Google Earth technology, allowing users to fly virtually around the planet and analyze movements and changes in the genomes, or genetic blueprints, of avian flu sub-strains that have been sequenced since the virus was first detected in Guangdong, China, in 1996.
The researchers used the technology to chart the spread of H5N1 through Asia, Indonesia, the Middle East and Europe by various hosts, including its transport by specific orders of birds and mammals, said CU graduate student Andrew Hill, a study co-author. They also used the supermap to track key genetic traits prevalent in some avian flu genomes that appear to confer the ability of H5N1 to more readily infect mammals, including people, he said.
"This is a completely new method of integrating and sharing knowledge about disease spread, giving people a quick and easy way to make sense of the changes,” said Hill, chief architect of the visualization portion of the collaborative research project. A paper by a team led by Daniel Janies of Ohio State University and involving Guralnick, Hill and American Museum of Natural History researchers Eric Waltari and Ward Wheeler was published in the April issue of Systematic Biology.
Like the legend of a roadmap, colors and symbols on the supermap indicate which types of hosts carry the virus or the distribution of genotypes of interest, Hill said. "This allows us to test hypotheses on the geographic distribution of strains that contain what laboratory studies have suggested are the key genotypes that allow avian strains of the influenza virus to infect mammals,” Hill said.
The team studied genomic sequence data from 351 strains of the avian flu collected in the field, said Guralnick, also curator of invertebrate zoology at the University of Colorado Museum. A click by users on viral "isolates” generates computer windows revealing diagnostic mutations that make each strain unique, and the information is linked by computer to the National Institutes of Health's GenBank, a database with more than 75 million sequence records.
The team looked at two key proteins found on the surface of H5N1 strains known as hemaglutinin, or HA, and neuraminidase, or NA. Scientists think if a virulent strain of H5N1 adapts to succeed at human-to-human transmission, it would likely involve mutations by the two proteins. No mutations associated with NA and HA were linked to any specific bird or mammal host, Guralnick said.
But the team found a strong association between a specific genotype, Lysine-627, in a segment of the viral genome called the polymerase basic protein, or PB2, and in mammalian hosts in the field. "While this genotype is not exclusive to mammals, we think it is important to track how this PB2 mutation is spreading, because it appears to be so infective and deadly in mice,” Janies said.
The team also used the supermap to visualize the spread of H5N1 in various parts of the world by specific orders of birds and mammals, including waterfowl, domestic fowl, shorebirds, raptors, songbirds, hoofed mammals and carnivores, Guralnick said.
In one instance, the supermap shows a direct line spreading from Thailand to Europe in a single rapid event, illustrating a 2004 incident when several infected eagles were smuggled into Belgium, Hill said. While the birds were immediately seized and confined, preventing further spread, the supermap portrayal of the event illuminated how illicit wildlife trading can trigger leaps in virus transport.
The avian flu epidemic was detected in wild aquatic birds in Guangdong in 1996 and spread to chickens and a few people in Hong Kong by 1997. From 1997-2005, the virus emerged in several Southeast Asian countries and spread through multiple hosts to Japan, Korea, Russia, the Middle East and India. In the past two years, the virus has spread to Western Europe and re-emerged in Korea.
While H5N1 is not highly communicable to people or among people, experts are concerned that future mutations have the potential to make the bird flu significantly more contagious.
