Scientists study avian influenza to make world a better place

By ANDREA JOHNSON, Assistant Editor
Thursday, July 3, 2008 11:29 AM CDT

David Suarez

According to the Economic Research Service, American consumers eat about 74 pounds of poultry products per year. For that reason, the poultry industry is dedicated to providing a good, healthy product and keeping their flocks free of diseases like avian influenza.

Many scientists and researchers, along with scientific institutions, devote themselves to studying and defeating poultry diseases.

Iowa ranks first in egg production, while Minnesota ranks first in turkey production, according to the National Ag Statistics Service.

Back in the 1980s and early 1990s, poultry producers here dealt with outbreaks of avian influenza. Scientists hypothesized the disease was carried by wild birds.

Avian influenza is normally found in wild birds such as ducks, gulls and some shore birds. When wild birds interact with poultry populations, avian influenza viruses can jump species and adapt to sicken chickens and turkeys.

Large flocks of turkeys that were kept outside were prone to catching avian influenza, so farmers moved the birds into containment housing.

Now, almost all poultry are raised indoors. The outbreaks of avian influenza have dropped almost to zero in the United States.

One type of avian influenza that has not reached the U.S. is H5N1. This highly pathogenic virus has crossed the species barrier to infect humans.

David Suarez is research leader of the Exotic and Emerging Avian Viral Disease Research Unit at the Southeast Poultry Research Laboratory. The lab is located in Athens, Ga., and operated by the Agricultural Research Service (ARS).

Suarez oversees the ARS avian influenza virus repository at the lab.

As part of his work, Suarez has overseen the complete genetic coding sequences of 150 different avian influenza viruses.

The sequencing information can help researchers better understand virus biology and improve diagnostic tests for avian influenza viruses.

“The overall plan is now that we have a lot of influenza viruses available to us, we are getting more and more information about how each virus affects different species,” said Suarez in a phone interview. “Some will infect chickens, but will not cause disease. There's some that obviously can cause very serious disease.”

Public and private scientists are assisting in the project.

The partners include USDA's Animal and Plant Health Inspection Service's Wildlife Services as well as researchers from the University of Georgia, the Ohio State University, the University of Alaska-Fairbanks and the University of Delaware.

Virus isolates were prepared at the ARS Southeast Poultry Research Laboratory. Scientists there separated the ribonucleic acid or RNA, and sent the noninfectious genetic material to industry collaborator, SeqWright Corporation, in Houston, Texas.

SeqWright researchers sequenced the genomes of each virus.

The Southeast Poultry Research Lab then reviewed the sequence information for release to GenBank. GenBank is the National Institutes of Health's genetic sequence database.

“This is really the first important step,” said Suarez. “We're trying to get the genetic information for these different viruses. Then we're going to try to connect that genetic information with its ability to cause disease. We want to try to figure out why some viruses are more pathogenic for poultry or for other species.”

Currently, most U.S. poultry are not vaccinated for avian influenza. The only exception is some turkey farmers may vaccinate breeding flocks that are located near swine farms. Turkeys can be susceptible to swine influenza.

Suarez said that it is easier to sequence a virus than bacteria. That's because a virus is a simpler form of life than a bacteria.

Sponsored by a presidential initiative on avian influenza, the project's ultimate goal is to sequence about 1,000 avian influenza viruses from the Southeast Poultry Research Lab repository.

The viruses were collected from poultry and wild bird species around the world.

Ultimately, the sequence information will be combined with studies that have compared the viruses' ability to infect and cause diseases in chickens, turkeys and ducks.

The analysis of the sequences - plus the biological data - will provide new insights into how viruses cause disease in man and animals.

“We are interested in wild bird isolates, as well as poultry isolates, to get a better estimate of which viruses that are coming from wild birds present the greatest risk of introduction into our poultry population,” said Suarez.

“If this information can help us predict which viruses are most likely to move - or if the information can help us with our surveillance of wild bird viruses - that would be the goal of the project.”

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