Decades of antibiotic overuse have bread new generations of super-bacteria that can go on living even when hit with the most potent drugs we’ve got. Scientists are scrambling to discover new antibiotic compounds, but it’s slow going. Oh, there are plenty of chemicals that will kill bacteria, but many of them are toxic to humans as well. That’s the case with many compounds in wasp venom, but a team from MIT has managed to tweak one of these molecules to be safe for people and toxic to bacteria.
The research focused on Pseudomonas aeruginosa, a persistently nasty bacterium that exists basically everywhere. It’s what’s known as an opportunistic pathogen because it tends to cause disease when another condition is present. For example, it causes potentially fatal pneumonia in cystic fibrosis sufferers and skin infections in those recovering from burns. Pseudomonas aeruginosa is of particular concern because it’s resistant to most common antibiotics. The bacterium has picked up resistant genes, and its cellular structure helps shield it from many antibiotic molecules.
That brings us to Polybia paulista, a South American Wasp with a nasty sting. Its venom contains a cocktail of peptides (amino acid complexes) that can affect cells inside the victim. In fact, one Polybia paulista peptide is already under investigation as a chemotherapy agent. This study explored uses for a peptide called polybia-CP, which can cause cell death and inflammation in humans, but it’s only 12 amino acids long. That makes it relatively easy to characterize and modify.
These wasps kindly donated peptides for study.
Polybia-CP has a helical structure, which scientists believe is capable of disrupting cell membranes. The team made small changes to polybia-CP, and then tested how the new molecules fared against bacteria. With iterative changes, the researchers arrived at a version of polybia-CP that can kill bacteria but doesn’t harm human cells—although, that assertion is based on a mouse model. There’s no reason to think it’s inaccurate, though.
The experiments found a high dose of polybia-CP could completely clear Pseudomonas aeruginosa infection in mice after about four days. This is described as “surprising.” The team is currently focusing its efforts on additional polybia-CP modifications that could make it effective against Pseudomonas aeruginosa at lower doses. With enough time and testing, polybia-CP could become a viable treatment alternative when existing antibiotics fail.
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