Wasp venom contains a potent mix of chemicals that can injure and even kill other animals when introduced through a nasty, hypodermic needle-like stinger. Simply being in proximity with one of these insects is a stressful experience, to say nothing of the pain of receiving an actual sting. But now, thanks to research from the Massachusetts Institute of Technology (MIT), you might have a newfound appreciation for the critters.
Writing in the journal Nature Communications Biology, lead author Marcelo Der Torossian Torres and his colleagues explain that many small protein molecules found in wasp venom can kill species of bacteria that are pathogenic to humans. And, according to their experiments in vitro and in mice, modified versions of these peptides show exciting potential for development into new antibacterial agents. In case you’ve been busy focusing on humanity’s other ongoing crises, effective new antibiotics are sorely needed to prevent the antibiotic resistance apocalypse.
“We’ve repurposed a toxic molecule into one that is a viable molecule to treat infections,” author Cesar de la Fuente-Nunez said in a statement.
The group began their study by analyzing a dozen or so antimicrobial peptides (AMPs) found in the venom of the South American social wasp (Polybia paulista), which just so happens to also create anti-cancer chemicals. To find the AMP with the most promising broad-spectrum activity, each was tested against the classic bacterial species of Escherichia coli, Pseudomonas aeruginosa (both Gram-negative), and Staphylococcus aureus (Gram positive). The winner of these in vitro experiments was an alpha helix-structured molecule known as Pol-CP-NH2. Like most AMPs produced by insects and arachnids, Pol-CP-NH2 eliminates bacteria by interfering with their outer membrane.
Next, the researchers started playing around with the chosen peptide’s 12-amino acid structure to see if they could create a version that is both more effective against bacteria and harmless to human cells. The former was achieved by testing several dozen Pol-CP-NH2 variants against seven strains of bacteria and two of fungus. After modifying their candidate peptides using insights gained from these acitivty tests, the molecules were assessed for toxicity using a line of human embryonic kidney cells.
“It’s a small enough peptide that you can try to mutate as many amino acid residues as possible to try to figure out how each building block is contributing to antimicrobial activity and toxicity,” de la Fuente-Nunez said.
Finally, seven variants and the naturally occurring form of Pol-CP-NH2 were tested in mice who had been infected with P. aeruginosa, a widespread and common bacterium that may cause respiratory and urinary tract infections in humans. According to the CDC, multidrug-resistant Pseudomonas now poses a serious threat to public health.
Remarkably, a single high dose of the variants completely cleared the Pseudomonas infection just a few days, with no indication of adverse effects. Several other variants were successful at reducing the infection following a single dose.
“After four days, that compound can completely clear the infection, and that was quite surprising and exciting because we don’t typically see that with other experimental antimicrobials or other antibiotics that we’ve tested in the past with this particular mouse model,” de la Fuente-Nunez added.
Moving forward, the team have already begun experimenting with new variants that could clear infections at lower doses. They also note that their methods could be used by other groups who are focused on characterizing – and potentially improving – the activity of other natural antimicrobial molecules.
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