New anthrax drug to serve as insurance against bioterrorism

This story was written for J310F Reporting Words, Spring 2016

On a December day in 2005, Jean Patterson donned her gloves, mask and biosafety suit, and walked into her lab to check on a group of guinea pigs infected with one of the world’s deadliest biological weapons—anthrax.

Normally, all the guinea pigs would be dead or dying. Anthrax has a mortality rate of over 80%, and the guinea pigs had been administered more than 500 times the lethal dose. However, on this morning, the guinea pigs were still alive and squeaking.

“Under normal circumstances, certainly even humans would die, they wouldn’t have survived that level of toxin,” Patterson said in an interview with UT News. “But day after day, we came into lab to find the animals still happy and healthy.”*

The guinea pigs had been saved by the administration of the antibody-based drug now known as Anthim, which was approved by the FDA last month. Anthim was developed in part by a team of UT researchers—Brent Iverson, George Georgiou, and Jennifer Maynard.

Since its initial development in the early 2000s, Anthim has come a long way from its humble beginnings in guinea pigs.

The drug was licensed by the New Jersey-based pharmaceutical company Elusys, and is now in the process of being distributed to medical supply outposts throughout the country as an insurance policy against the threat of biological weapons. These outposts are part of the Strategic National Stockpile, a national repository of vaccines, medicine, and other emergency supplies.

“[This insurance policy] is very important psychologically, because the big thing about anthrax is that it’s really easy to make,” Iverson said. “It is really easy to make these spores and very easy to weaponize them.”

Anthrax, the name for the disease caused by toxins produced by Bacillus anthracis, a common environmental bacteria, does indeed have a long and infamous history as a biological weapon. In the weeks following 9/11, 17 Americans were infected with anthrax. Five died. The bacteria can be grown in a garage, and the spores—seed-like capsules of dormant bacteria—distributed by mail, sprayed from a plane or truck, or scattered via biological weapons, such as anthrax bombs developed by the US after World War II.

Although it is not spread from person-to-person, anthrax spores are able to live for up to a century, making it hard to eliminate from the environment. In addition, Iverson said that it is relatively simple to engineer antibiotic-resistant strains of the bacteria.

“The level of sophistication you need is not very high,” Iverson said. “I made this statement—I could be wrong—but I think it is easier to make anthrax than a good batch of beer.”

Treatments for anthrax generally involve a course of antibiotics, coupled with an antitoxin to eliminate their toxic products.

“Generally, it doesn’t matter toward the end how much antibiotics you get to kill the bacteria,” Patterson said. “You have to do something about the toxin that has been building up in the body.”

The toxin latches on to white blood cells involved in immune response, turning them against the infected person’s body.

“It commands the immune system to kill the person,” Iverson said. “It essentially says, ‘you are under attack, go kill everything,’ except there is nothing to attack.”

When Anthim was tested on Patterson’s guinea pigs, the results were unexpected in more than one way. After Patterson infected the guinea pigs, she did not give them the usual two-fold treatment of antibiotic and antitoxin—she just treated them with Iverson’s antibody.

“We expected the antitoxin to extend the lifespan of the infected animals,” Patterson said in an interview with UT News, “but since we did not couple it with antibiotics, we thought that the bacteria would continue to replicate, and the increasing amount of toxins would eventually overpower the treatment.”

That was not what happened; the antibody in Anthim destroyed the toxin, but also the bacteria. Iverson hypothesized that without its toxin as a defense, anthrax was barely a threat.

“It turns out that anthrax apparently never evolved to evade an immune response because it killed its animals so quickly,” Iverson said. “If you buy the animal some time, the belief was that the animal’s own immune system took out the anthrax, because you take its big weapon out so it was defenseless.”

Accordning to Iverson, it is this property makes Anthim extremely useful and appealing to the government, for use in both the national stockpile and for military applications.

“I think it is reassuring to know that it is not just biodefense,” Iverson said. “There is actually is a stockpile of medical supplies in case something really bad happens.”

Iverson said said he hopes that the stockpile of his drug will serve as a deterrent to terrorists who might plan to use anthrax as a bioweapon.

“It is as psychological as anything else,” Iverson said. “God forbid there ever is a biological attack. One would hope that the bad guys know we have a cure so they just don’t do that.”

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