As harmful bacteria continue to become resistant to standard antibiotics, it gets increasingly important to come up with alternatives. With that in mind, scientists at MIT have looked to a species of wasp, and found an effective antibiotic in its venom.
It was already known that wasp and bee venom contains peptides (short chains of linked amino acids) that kill bacteria. Unfortunately, though, these compounds have also proven to be toxic to human cells.
Not to be dissuaded, an MIT team recently analyzed the venom from the South American Polybia paulista wasp. The scientists found that one of the bacteria-killing peptides within that venom was only 12 amino acids long, suggesting that it would be relatively easy to manipulate within the lab.
They proceeded to produce several dozen variants, each with a differing helical structure (the manner in which the amino acids are arranged) and with a different degree of hydrophobicity (repellence to water) – these qualities determined how effective each variant was at killing microbes by destroying their cell membranes.
Based on their findings, the researchers produced a few dozen more particularly effective variants, then tested how toxic they were to human embryonic kidney cells grown in a glass dish. Those that weren't toxic were subsequently tested on mice infected with Pseudomonas aeruginosa bacteria, which frequently causes respiratory and urinary tract infections. While several of the variants reduced the infection, one of them (given at a high dose) eradicated it completely within four days.
The scientists are now creating yet more variants of the peptide, hoping to produce one that will be just as safe and effective, but at lower doses. They also believe that their findings could be used to develop new antibiotics from other naturally-occurring antimicrobial peptides.
"I do think some of the principles that we've learned here can be applicable to other similar peptides that are derived from nature," says postdoc Cesar de la Fuente-Nunez, one of the senior authors of a paper on the research. "Things like helicity and hydrophobicity are very important for a lot of these molecules, and some of the rules that we've learned here can definitely be extrapolated."
The paper was published this week in the journal Nature Communications Biology.
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