November 30, 2010

Fly, Fly Away — Research on the Genetics of the Bird Flu

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Swabs taken from birds and their environment at live bird markets of New York City are brought regularly to Cornell University. The University’s Animal Health Diagnostic Center tests these samples to monitor the outbreak of the H5N1 virus — commonly known as “bird flu.” This virus is  found in avian intestines; it is highly contagious amongst birds, traveling through their saliva, feces and nasal secretions.

Prof. K. A. Schat, microbiology and immunology, unit director of avian health, works to understand the genome of the H5N1 virus.

In case that the virus is detected in the samples at the University, the swabs are immediately sent to the National Veterinary Services Laboratories in Ames, Iowa for further investigation.  If confirmed, immediate and strict control measures are initiated, including a procedure of culling — a process through which infected birds are isolated — of the infected farm and farms within a radius of approximately five miles.

Schat has worked for 40 years in the field of virology.  In 2006, he began to research the H5N1 virus.  To understand the pathogenesis – the chain of events leading to the symptoms of the virus — of H5N1, Schat works with the CDC, Australian Animal Health Laboratory (AAHL) of the CSIRO Livestock Industries, and the College of Veterinary Medicine.

Shuttling between Ithaca and Australia, to work in the high containment facilities of AAHL with bio-safety level III, Schat found that, “In my experiments, chickens had a mortality rate of 100 percent, duck had [a rate] of 30 percent, and the remaining [species] made antibodies.”

Contact with poultry can infect humans. Commercial poultry farms are cautious, and generally, their procedures prevent infections. The infection rate is currently low, and the virus is not very contagious.

In 1997, the first human case of H5N1 was reported in Hong Kong. Though it has not happened since the virus was discovered, the possibility exists that H5N1 may mutate.

Some non-contagious human cases of H5N1 have been reported in Indonesia with an 83 percent mortality and Egypt with a 30 percent  rate. Studies are being conducted to understand the impact on humans.

Schat said, “Only a specific change in the H5N1 virus can cause a contagious infection in humans. It is like a lock and key model. The current Asian virus-key is unable to lock into the cell-lock in the upper respiratory tract of humans.”

He did not comment on the consequences of a mutation on humans.

No treatment exists to manage H5N1 in humans. Schat said that when a mutation occurs, hopefully, researchers will have the resources to deal with it. “Even if the flu becomes resistant to a single drug, a cocktail of drugs would be more effective. It is hard to say on what will happen.”

Bird vaccination is also not a suitable option to prevent the spread of the virus. According to Schat, vaccinations are not absolutely effective, and in the long run, vaccination can foster mutations in the virus.  Although China, Egypt, Indonesia and Vietnam vaccinate and treat their birds, the U.S. exterminates its infected birds immediately.

According to Schat, in this fascinating and highly competitive field of avian viruses, the future holds many more questions: “What is the difference of impact in humans and different birds? How can we make the vaccines based on molecular techniques? How can we make a vaccine that fights the disease, super-infection, and also cure it?”

Original Author: Poornima Gadamsetty