Scientists discover secrets to cholera defenses

Scientists from the University of Texas recently discovered how cholera bacteria manage to evade one of the innate human immune responses.

The end of the 50 year mystery could lay the foundation for the development of a new class of antibiotic that does not incapacitate pathogenic bacteria, but instead disables their defenses so the immune system can destroy them, according to

"If you understand the mechanism, the bacterial target, you're more likely to be able to design an effective antibiotic," lead researcher Stephen Trent, an associate professor of molecular genetics and microbiology at the University of Texas at Austin, said, reports.

The study, which was published in the Proceedings of the National Academy of Sciences, explains that the bacterium's defense is bolstered by one or two small amino acids that are attached to larger molecules called endotoxins. These endotoxins cover approximately 75 percent of the bacterium's outer surface.

"It's like it's hardening its armor so that our defenses can't get through," Trent said, according to

The amino acids alter the electrical charge of the bacterium's outer surface, changing it from negative to neutral. The molecules the immune system uses to fight such bacteria, called cationic antimicrobial peptides, are positively charged and are, therefore, unable to attach to the bacterium.

"It's orders of magnitude more resistant," Trent said, reports. "If we can go directly at these amino acids that it uses to protect against us, and then allow our own innate immune system to kill the bug, there could be less selection pressure."

Trent's lab is currently searching for compounds that will allow the CAMPs to bind with bacterium. Trent said that the benefits of such an antibiotic could be considerable because it could be useful against any bacteria that use a similar defense. In addition, because it disarms the bacteria instead of killing it outright, it might take longer for resistance to develop.