Safe antibiotics developed from wasp venom

Scientists at MIT have created variants of the peptides from a South American wasp's venom that can kill bacteria but are nontoxic to human cells.

The venom of insects such as wasps and bees is full of compounds that can kill bacteria, according to the study published in the journal Nature Communications Biology.

However, many of these compounds are also toxic for humans, making it impossible to use them as antibiotic drugs.

In a study of mice, the researchers found that their strongest peptide could completely eliminate Pseudomonas aeruginosa, a strain of bacteria that causes respiratory and other infections and is resistant to most antibiotics.

"We've repurposed a toxic molecule into one that is a viable molecule to treat infections," said Cesar de la Fuente-Nunez from the Massachusetts Institute of Technology (MIT) in the US.

"By systematically analysing the structure and function of these peptides, we've been able to tune their properties and activity," said Fuente-Nunez.

The peptide that researchers focused on was isolated from a wasp known as Polybia paulista.

This peptide is small enough -- only 12 amino acids -- that the researchers believed it would be feasible to create some variants of the peptide and test them to see if they might become more potent against microbes and less harmful to humans.

Like many other antimicrobial peptides, this venom-derived peptide is believed to kill microbes by disrupting bacterial cell membranes.

To measure the peptides' toxicity, the researchers exposed them to human embryonic kidney cells grown in a lab dish.

They selected the most promising compounds to test in mice infected with Pseudomonas aeruginosa, a common source of respiratory and urinary tract infections, and found that several of the peptides could reduce the infection.

One of them, given at a high dose, could eliminate it completely, researchers said.

"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," Fuente-Nunez said.