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Brooks laboratory aids in avian flu detection

  • Published
  • By Rudy Purificato
  • 311th Human Systems Wing
BROOKS CITY-BASE, Texas (AFMCNS) --  A Brooks City-Base epidemiology laboratory is working to develop more effective and timely methods for detecting avian flu to support a worldwide Air Force surveillance program designed to safeguard American military personnel from a potential outbreak.

The Air Force Institute for Operational Health's Epidemiology Division is at the forefront of an Air Force initiative to create more reliable and faster testing procedures for H5N1, the influenza virus that scientists believe has spread from birds to humans across three continents.

"We're developing assays (DNA testing) to rapidly screen for avian flu," said Maj. David Eddington, a molecular biologist who is the AFIOH Epidemiology Division's microbiology chief. He said Air Force scientists began the process this year of developing new technology to detect avian flu. The new assay uses polymerase chain reaction, or PCR, technology. Additionally, the organization is capable of performing molecular sequencing of the viral genome which helps detect mutations.

Since first appearing in Asian poultry in 1997, the Highly Pathogenic Avian Influenza, as it is scientifically known, mostly has killed people who have been in direct contact with domesticated fowl. The deadly respiratory strain has become zoonotic (jumping from non-human host to people), leading to the first reported human death in 1997 in Hong Kong. Scientists fear that its transmission between humans could trigger a pandemic.

To do that, it would have to mutate. During the last century, mutations in influenza viruses caused pandemics that killed millions of people in 1918, 1957 and 1968. For avian flu to become pandemic, it would have to mix its genes with those from the naturally circulating flu 'A' strain to transform so that it becomes easily transmissible from human to human, said Linda Canas, chief, AFIOH Virology section.

Influenza viruses are known to transform with some frequency. This is why surveillance exists to determine which strain is best for the current vaccine, said Major Eddington.

"With the influenza virus, two different mutations called 'shift' and 'drift' exist," said Major Eddington. He said the drift mutation process involves a small nucleic acid variation that occurs after the virus invades a cell and during replication of its nucleic acid genome. Shift mutations, however, involve larger genetic segments and can occur in naturally circulating flu 'A' strains.

"The problem (leading to potential pandemics) is someone infected with a normal circulating flu 'A' strain is (also) co-infected with avian flu," Major Eddington said. The co-mingling of virus strains creates conditions for gene sharing. This occurs after an infected cell produces gene segments from both strains and they mix together during the process called self assembly. During this process, the virus mutates into a new variation in which humans have no immunity.

"The Air Force has stepped up worldwide avian flu surveillance that includes research sites in South America and Thailand," Ms. Canas said. Since 1997, the Air Force has been executive agent for the laboratory-based Global Emerging Infections System.

This tri-service system relies on a network of global sentinel (early warning) sites, Ms. Canas noted. "Our surveillance data is shared with the Food & Drug Administration's Vaccine and Related Biological Products Advisory Committee," she said.

This information is compared with other surveillance information and used to develop North American flu vaccines. Typically, flu vaccines are composed of two 'A' strains and one 'B' strain. All flu vaccines and anti-flu prescription drugs, such as the FDA-approved prophylactic Tamiflu, are made overseas.

Air Force scientists know that current flu vaccines offer no protection against avian flu. Ms. Canas said, "We have very little information on the use of Tamiflu. The only thing that it seems to help is morbidity (onset of illness). We don't know how it will affect mortality."