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Scientists study vaccines against biological weapons
(10-10-01)

A microbiologist at The University of Texas Health Science Center at San Antonio (UTHSC) is working out new vaccines for anthrax and tularemia, two potential biological weapons that could wipe out military and civilian populations.

Karl Klose, Ph.D., assistant professor of microbiology, has received $1.5 million from the National Institutes of Health to pursue the studies, which could lead to oral vaccines for the dangerous infections within five years. Study collaborators include Kent Lohmann, Ph.D., of Brooks Air Force Base, Jean Patterson, Ph.D., of the Southwest Foundation for Biomedical Research, and John Gunn, Ph.D., assistant professor of microbiology at UTHSC.

Anthrax, a common soil bacterium, is considered the ideal bioterrorism weapon because of the potential ease with which it could be spread. It is a sneaky killer, beginning with flu-like symptoms that are difficult to diagnose. “A terrorist could be on a plane and out of the country before anyone knew what happened,” Dr. Klose said.

Anthrax, once breathed in, releases a toxin that can kill up to 80 percent of victims. Tularemia can kill approximately 60 percent. Dr. Klose and his colleagues hope to spur the body’s immune system to knock out these bacteria before they cause damage. The researchers are looking to help from an unlikely source – Salmonella, a bacterium that causes food poisoning.

Drs. Klose and Gunn have studied the characteristics of Salmonella for a number of years, and they believe it can be adapted to serve as a delivery system for anthrax and tularemia vaccines. “We have crippled the Salmonella strain so that it can live in the intestine without causing disease,” Dr. Klose said. “Next, we want to insert a small piece of anthrax – the portion that comprises the current injectable vaccine – into the Salmonella. We will vaccinate mice and other animals and monitor them to see if they develop resistance to anthrax or tularemia.”The work will be performed in a Level 4 biocontainment facility at the Southwest Foundation for Biomedical Research. Brooks AFB personnel will test the vaccinated animals to make sure they are expressing immunity to anthrax and tularemia.

Often associated with sheep and cattle, anthrax usually infects only the skin, causing black boils that are treatable. When breathed in, however, the bacterium multiplies and manufactures its toxin. Flu-like symptoms soon appear, followed by complete organ failure and death.

“The difficult thing about both anthrax and tularemia is that they can live inside macrophages, which are the cells that repel foreign invaders from our bodies,” Dr. Klose said. “Anthrax and tularemia use macrophages as ‘taxis’ to travel inside the body and multiply.”

The specter of bioterrorism looms larger in the wake of the Sept. 11 terror attacks on New York and Washington. New vaccines for anthrax and tularemia could save the lives of millions in the event a terrorist tries to disseminate these bioweapons.

The U.S. military instituted mandatory anthrax vaccinations for its personnel after the Gulf War. The current vaccine is effective but requires a series of six injections. Some military personnel have objected to the vaccine because it can cause serious reactions after the third or fourth injection, including flu-like symptoms and vision distortions. “We’re trying to develop a safer, less expensive and more effective vaccine that would be easy to administer and that would protect people against biowarfare,” Dr. Klose said. “A terrorist act using anthrax is probably only a matter of time.”

Dr. Klose has organized a bioterrorism symposium as part of the annual meeting of the Texas Branch of the American Society for Microbiology. Five scientific experts studying potential bioterrorist threats will give the session, which is scheduled for 8 a.m. to noon Nov. 17 at the Sheraton Gunter Hotel. The cost is $10 per person and the public is invited.

Contact: Will Sansom or Aileen Salinas