Blood of Komodo dragons could provide antibiotic alternative

2Meredith uses computers to simulate how molecules move and wiggle. Her calculations might help us get a clearer picture of what these molecules look like and how they act.

In January of this year, the Center for Disease Control and Prevention (CDC) published a much more frightening Morbidity and Mortality Weekly Report than usual: a woman in Nevada had perished from a bacterial infection that no antibiotic in America could fight. Doctors administered 26 different antibiotics to no avail.

“If we’re waiting for some sort of major signal that we need to attack this internationally, we need an aggressive program, both domestically and internationally to attack this problem, here’s one more signal that we need to do that,” Lance Price, the head of the Antibiotic Resistance Action Center at George Washington University, told STAT News.

Recently, researchers at George Mason University made a discovery that could add to science’s arsenal against antibiotic resistance: the presence of powerful bacteria-killing chemicals in the blood of Komodo dragons.

All classes of life have some natural immune resistance to bacteria that are harmful to them. The first line of defense against bacteria and viruses are chemicals called antimicrobial peptides (AMPs), which are typically found in the tissues and organs in the animal that are most exposed to airborne diseases. Natural and man-made AMPs have been the subject of intense study due to their ability to kill or stop the growth of antibiotic-resistant bacteria.

However, AMPs do have weaknesses when considering them as a way to fight bacterial infections in a context such as the doctor’s office: they are sensitive to their environment, and easily break down when confronted with certain natural chemicals or a high pH; they are costly to make or isolate; it is difficult to engineer them to fight specific strains of bacteria; and several kinds of bacteria are AMP-resistant. Luckily, many kinds of AMPs exist, even within the same organism–300 different AMPs live on the surface of a frog’s skin. There is therefore ongoing research to find and categorize different AMPs found in nature, to find the ideal version to fight different kinds of bacteria.

The researchers at George Mason University were particularly drawn to the Komodo dragon because of its incredibly robust immune system. Not only does it recover from physical battles with other members of its species–which often result in open wounds–but it also commonly eats bacteria-ridden dead meat, and bacteria from its bite can contribute to the death of live prey it attacks. In all, the saliva of the Komodo dragon was found to contain 57 separate strains of bacteria, over 90% of which could be classified as disease-causing strains. That this lizard could live with so many disease-causing bacteria in its mouth and also frequently endure bites from other members of its species justified a deeper look at its collection of AMPs.

The researchers found 48 previously undiscovered AMPs in Komodo dragon blood, and tested 8 of them against 2 antibiotic-resistant strains of bacteria: MRSA and pseudomonas aruginosa. There is only one antibiotic–vancomycin–known to be effective against MRSA, which is responsible for over 10,000 deaths in the U.S every year. Not only that, the bacteria has already developed strains that are resistant to this antibiotic, which has doctors extremely nervous. In the lab, all 8 AMPs were able to kill P. aruginosa, and 7 were able to effectively kill MRSA!

There are not currently any AMPs being used as therapeutic agents for human patients, but labs across the country are constantly finding more and testing their bacteria-killing potency. The Komodo dragon AMPs join a growing collection being studied by scientists who are racing to find new antimicrobial treatments as bacteria are racing to find ways around them.

Many people ask Dr. James Johnson, a professor who studies infectious diseases at the University of Minnesota, how scared the public should be about antibiotic resistance. He gave his response to STAT News: “We’re already falling off the cliff,” he said. Hopefully AMP research will eventually help us pull ourselves back up.

 

Sources:

  • Bishop, B. M. et. al. (2017). Discovery of Novel Antimicrobial Peptides from Varanus komodoensis (Komodo Dragon) by Large-Scale Analyses and De-Novo-Assisted Sequencing Using Electron-Transfer Dissociation Mass Spectrometry. Journal of Proteome Research. doi:10.1021/acs.jproteome.6b00857
  • Branswell, H. (2017, January 12). Nevada woman dies of superbug resistant to all available US antibiotics. Retrieved February 28, 2017, from https://www.statnews.com/2017/01/12/nevada-woman-superbug-resistant/
  • Chen, L., Todd, R., Kiehlbauch, J., Walters, M., & Kallen, A. (2017, January 13). Notes from the Field: Pan-Resistant New Delhi Metallo-Beta-Lactamase-Producing Klebsiella pneumoniae — Washoe County, Nevada, 2016. Retrieved February 28, 2017, from https://www.cdc.gov/mmwr/volumes/66/wr/mm6601a7.htm?s_cid=mm6601a7_w
  • Bahar, A. A., & Ren, D. (2013). Antimicrobial Peptides. Pharmaceuticals, 6(12), 1543-1575. doi:10.3390/ph6121543

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