CSIRO Starts Coronavirus Vaccine Trials Using Ferrets

CSIRO Starts Coronavirus Vaccine Trials Using Ferrets
Image: Getty Images

CSIRO has announced it’s working on pre-clinical trials for coronavirus vaccine candidates using an animal they previously worked with during the SARS outbreak in the early 2000s ” the humble ferret.

Australia’s national science agency, CSIRO, is teaming up with the Coalition for Epidemic Preparedness Innovations”¯(CEPI) to begin pre-clinical trials in the race to put a stop to the coronavirus pandemic that’s shutting down life as we know it.

The trials are expected to last three months and will see two potential vaccines tested on ferrets. If they’re found to be safe and the results look promising, the vaccines will then be tested on humans. It’s anticipated that early results will be known by June and if all goes well, human trials for the vaccine could begin as early as July. CSIRO, taking an optimist’s view, believe an early 2021 production of the vaccine is not completely out of the picture.

Balancing speed and safety in the race to find a coronavirus vaccine

The study’s lead researcher, Professor Trevor Drew, said while there was an urgency for a vaccine, it was important to balance that with proper testing for safety and efficacy.

“We have been studying SARS CoV-2 since January and getting ready to test the first vaccine candidates as soon as they are available,” Professor Drew said in a media release.

“We are carefully balancing operating at speed with the critical need for safety in response to this global public health emergency.”

Two proposed vaccines are being looked at by the study ” one from The University of Oxford and one developed by the U.S. pharmaceutical company, Inovio.

The first of those is what’s called a vector vaccine and can be injected via a nasal spray as well as the standard needle method.

“It uses a defective virus ” of a different type [of virus] ” to introduce the proteins of the SARS CoV-2 to the immune system but it’s unable to replicate,” Professor Drew said in a research briefing.

“There’s no possibility of becoming ill through this type of vaccine but because it has this active element of presentation [of coronavirus], it is anticipated that it will… induce a nice immune response.”

Professor Drew said the Inovio candidate varies from the vector vaccine proposal in that it injects nucleic acid, encasing certain proteins of the virus that our human cells react to and replicate, which then forces our immune system to respond.

“We think it’s very important to take a multi-pronged approach to this as it gives us the best chance of success,” Professor Drew said.

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Ferrets chosen for having similar lung receptors as humans

Ferrets were chosen for the trials due to the CSIRO’s previous experience working with them when SARS broke out in 2003.

“We are very used to working with this model [ferrets] and so we did have prior knowledge both of the model and of the likelihood that SARS CoV-2 would infect these animals,” Professor Drew said in the briefing.

But it’s the physiology of the ferret that makes it a good candidate too, he added.

“The ferret, we do know, does have the specific receptor on cells in its lungs for the virus to be able to infect and this receptor is called ACE-2,” he explained.

“This receptor is seen on a number of animals but ferrets certainly do provide the best model for us to use because of the similarity of the receptor with the human.”

Interestingly, while the focus has been on how coronavirus can be spread through the mouth and nose, Professor Drew pointed out the ferret, like the human, has shown the virus can be found in faeces.

“We’re finding the virus is being excreted from the nose, from the mouth and from the anus so it’s very important that we understand not only what is happening in the human but what is also happening in the ferret,” Professor Drew said.

The researchers admitted they’re being careful to avoid what happened during the 2003 SARS vaccine trial when the ferrets experienced a more severe form of the virus after the vaccine candidate was administered.

Professor Drew said this happened because of the way the virus infiltrates cells and how the immune system tries to fight it off.

“We are obviously alert to the fact that, in some instances, when a human responds to the disease sometimes that immune reaction can actually cause damage to the lungs, in particular, but possibly also damage to other organs,” Professor Drew said.

“The basis of this immune response is that when cells of the immune system see an infected cell, they tell it to kill itself so this signal can cause overt damage to the lung if there are a lot of cells in the lung, which are infected at that time.”

It’s because of this reality that Professor Drew and the team will be paying careful attention to how the ferrets’ immune system responds to the introduction of the vaccines and if there are any adverse effects.

“We need to make sure that with any vaccine we trial, we need to measure its ability to reduce the defensive immune response, which actually gets rid of the virus, but without causing over damage to the tissues,” Professor Drew said.

One of a few coronavirus vaccine trials underway in Australia

While the CSIRO’s announcement is a welcome step forward for COVID-19 vaccine trials, it’s not the only one in the works.

In late March, a human trial for the tuberculosis vaccine, BCG, was announced. It would see 4,000 healthcare workers in hospitals around Australia be administered the vaccine in an effort to boost their immune system, which it’s proven to do outside of preventing tuberculosis.

That trial will run for six months with an interim review at three months so there’s still sometime before its effectiveness is determined.

Elsewhere, the University of Queensland has been developing a vaccine using existing anti-malaria drugs and HIV medication. It’s soon to start its own trials but it’s just another example of one of many being worked on around the globe.

But as we all know already, for now, we’re all just waiting with bated breath.

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