Scientists genetically engineer a new strain of fungus that could finally present a cure for a common tropical disease known as African sleeping sickness.
African sleeping sickness is a parasitic disease that targets the central nervous system with symptoms that include disturbed sleeping patterns.
In a new study published in the journal PNAS, scientists engineer a new strain of fungus Acremonium egyptiacum that produces an antibiotic for the disease.
"Our collaboration started about four years ago, and we have finally achieved our goal," Ikuro Abe, a professor from the University of Tokyo Department of Pharmaceutical Sciences, says in a press release.
Fungus Presents Ideal Antibiotic
The strain A. egyptiacum produces two different kinds of antibiotic, one of which is toxic to humans. The other type of antibiotic produced by the fungus has been discovered as a potential antibiotic for African sleeping sickness back in 1996.
One of the scientists who played a role in identifying this potential treatment is Professor Kiyoshi Kita, who retired from the University of Tokyo in 2016 and dedicated a huge chunk of his career to understanding the disease.
Although it's been more than two decades since the antibiotic was found, the scientists ran into roadblocks when it comes to reproducing it. Artificially synthesizing it is too expensive and using bacteria to produce it is infeasible.
Researchers Find A Cost-Effective Option
Abe's research team determined that the two antibiotics produced by A. egyptiacum are made from the same precursor molecule. Two different groups of enzymes produce the two different antibiotics.
"The gene cluster in the fungus is unique — through a simple genetic deletion, we have engineered a strain of the fungus that only produces high concentrations of the desired antibiotic," Abe explains.
By simply eliminating the genes responsible for the toxic antibiotic, the researchers can keep the precursor molecule and the genes producing the African sleeping sickness antibiotic unchanged.
With this engineered strain of fungus, the team is able to produce 500 milligrams of antibiotic for every liter of fungus developed in the laboratory.
"We think this is an exceptionally good production system," said Abe.
Research collaborators from Kikkoman Corporation will be developing ways to grow this fungus on an industrial scale and to purify the antibiotic.
Their production could be a game-changer, not just for African sleeping sickness, but also for other diseases. This antibiotic, called ascofuranone, has also shown potential as a treatment for cancer.
African Sleeping Sickness
The disease, also called human African trypanosomiasis, is transmitted by tsetse flies, which is an insect found only in sub-Saharan Africa. While the disease is generally limited to remote rural areas, travelers passing by affected regions risk infection.
If left untreated, the African sleeping sickness is often fatal, according to the World Health Organization.