Queensland researchers develop direct-acting antiviral to treat COVID-19

17 May 2021

A team of Australian and US scientists from Menzies Health Institute Queensland (MHIQ) at Griffith University and from US research institute City of Hope, has developed an experimental direct-acting antiviral therapy to treat COVID-19. Lead researcher Professor Nigel McMillan from MHIQ said: "It causes the genome to be destroyed and the virus can't grow anymore. So we inject the nanoparticles and they go and find the virus and destroy it just like a heat-seeking missile."

Griffith University's Professor McMillan said "it is almost as good as a cure" (Supplied: Griffith University)

The team’s research has been published in Molecular Therapy.

Professor McMillan said that while traditional antivirals like zanamivir and remdesivir reduced symptoms and helped people recover earlier, "this therapy actually stops the virus replicating, so the body can repair itself and the recovery will be much quicker," he said.

This next-generation antiviral approach used gene-silencing RNA technology called siRNA (small-interfering RNA) to attack the virus’ genome directly, which stops the virus from replicating, as well as lipid nanoparticles designed at Griffith University and City of Hope to deliver the siRNA to the lungs, the critical site of infection.

"This is the first time we have been able to package this up as a particle, send it through the blood stream to attack the virus.

"It travels to the lungs and it will actually enter all the lung cells, but only in the lung cells with the virus will it destroy. Normal cells are completely unharmed by this treatment."

Professor McMillan said that although it was "not a cure", because it was so effective "it is almost as good as a cure."

Infected mice treated with the therapy had improved survival rates and loss of disease. “Remarkably, in treated survivors, no virus could be detected in the lungs,’’ Professor McMillan said.

“Treatment with virus-specific siRNA reduces viral load by 99.9%. These stealth nanoparticles can be delivered to a wide range of lung cells and silence viral genes.

Professor McMillan said that this treatment was targeted towards those people with serious illness who are suffering, for example in ICU, where vaccines are too late.

"We basically should be able to eliminate people dying from this disease, if treated soon enough.

"It allows us to treat those people who are suffering from the virus who are very sick, or those who may perhaps be in danger of being exposed to the virus, such as those in hotel quarantine.

"It is an injection that would be delivered daily into someone in ICU for four or five days, or as a single injection for someone just exposed.

"They'd be assured they won't suffer from the disease itself."

Professor Kevin Morris, co-lead researcher from both City of Hope and Griffith University said: “This treatment is designed to work on all betacoronaviruses such as the original SARS virus (SARS-CoV-1) as well as SARS-CoV-2 and any new variants that may arise in the future because it targets ultra-conserved regions in the virus’ genome.”

“We have also shown that these nanoparticles are stable at 4°C for 12 months and at room temperature for greater than one month, meaning this agent could be used in low-resource settings to treat infected patients,” Professor McMillan said.

The results suggest that siRNA-nanoparticle formulations can be developed as a therapy to treat COVID-19 patients, as well as used for future coronavirus infections by targeting the virus’ genome directly.

“These nanoparticles are scalable and relatively cost-effective to produce in bulk,” Professor Morris said.

“This work was funded as an urgent call by Medical Research Futures Fund and is the type of RNA medicine that can be manufactured locally in Australia,’’ Professor McMillan said.

The treatment could be available as early as 2023, depending on the outcomes of the next phase of clinical trials.