Ellen Phiddian
Whether you’ve waited hours in line for a PCR test, or found yourself questioning the accuracy of a RAT, we’ve all been tired of viral testing in the past few years.
The technology used to make RATs and PCR tests accurate is the product of decades of scientific development. But the next leap in viral testing might be going back to basics – with yeast.
A group of Australian scientists is using baker’s yeast to test for viruses.
The fragments of yeast they’ve engineered are cheap and as accurate at spotting COVID-19 as PCR tests.
“Yeast is a very special organism. One: it’s very cheap,” says lead researcher Professor Matt Trau, a chemist at the University of Queensland.
“But the yeast has another feature, which was really striking to us. It is incredibly durable.
“The coating of the yeast cell wall has a molecule called a polysaccharide. That’s a very special molecule which makes the yeast incredibly stable.”
Yeast cells can be resuscitated after millions of years.
“That polysaccharide molecule protects the proteins: the active molecules, if you like, on the surface.”
Trau and colleagues have genetically engineered yeast cells to contain proteins that bind to parts of a certain virus.
Then, with the addition of more proteins, they can use light, electricity or dyes to show if the virus has been picked up by the yeast proteins.
“It’s like a very sensitive antigen test – a nanoscale RAT, but with the sensitivity of PCR,” says Trau.
They’ve just published a study in Nature Nanotechnology showing their yeast powder can pick up COVID infections.
“We’ve run a clinical trial to robustly test our technology on clinical samples from COVID patients against PCR and RAT tests,” says Trau.
“We’ve shown that our technology either matches or outperforms those tests.”
But because it’s been genetically engineered, the yeast could be used to spot other viruses too, like influenza.
At the moment, the nanoprobes could be slotted into existing testing systems – a “cheap, durable, convenient reagent that can replace existing reagents,” says Trau.
The researchers are looking to see if they can broaden its use further.
“What we’re developing now is a completely instrument free version of this, where the nanofragment itself will bind to the virus particle and then emit a signal that could be detected remotely without any equipment – either via phone, or eventually we dream of drones or even satellites detecting that signature,” says Trau.
“On the surface of the cell wall, we can program all of the processing components that would typically happen in the laboratory.”
Because yeast is so cheap and quick to make, it could even be used to monitor potential disease outbreaks and predict pandemics.
“If there’s a pandemic, within a week or two [we could] have RATs that can distinguish all of the variants, and then as the virus changes to different variants, within a week, we’d have the next ones ready for testing,” says Trau.
It could also be used on animals.
“You can imagine putting some of this in the feedstock of animals and monitoring it with your phone,” says Trau.
“Your phone might detect a glow, or light signal from the chickens’ faecal matter, if they’re exposed to a particularly dangerous virus.”
The nanoprobes have taken three years of work from over a dozen people to develop so far. They’re still, according to Trau, “very much in the research phase” – it will need years more work to get to commercial use.
“The translational process is one that does take time, unfortunately, and we’re very interested to partner with commercial entities to help us accelerate that process,” says Trau.