Since those findings, Dr. Robert Mabry of the Iverson and Georgiou laboratory has reformulated the antitoxin to make it last longer in the bloodstream. Dr. Mabry also produced the antibody in bacterial culture, which could eliminate the need for complicated and expensive IgG production in mammalian cell culture. Drs. Jean Patterson and Ricardo Carrión at SFBR, along with veterinary staff from the SFBR Department of Comparative Medicine, have tested the re-engineered antibody with guinea pigs to determine if the antitoxin could protect against a true infection with anthrax spores.
"We expected the antitoxin to extend the lifespan of the infected animals," says Patterson, "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."
In fact, results differed from the scientists' expectations, leading to the serendipitous discovery that the antibody effectively eliminates both the toxin and the anthrax bacteria.
In two separate experiments conducted in SFBR's biosafety level 4, maximum containment laboratory, researchers placed anthrax spores in the nasal passages of guinea pigs, mimicking exposure to inhalation anthrax. The doses were 250 to 625 times what would ordinarily be lethal to 50 percent of the animals. After 72 hours, the animals not treated with the antitoxin succumbed to the infection, but those that received the treatment were still healthy two and three weeks later.
"Day after day, we came into th
Source:University of Texas at Austin