Tackling the ‘silent pandemic’: breakthrough study puts first long COVID treatment on horizon

09 April 2025

Tackling the ‘silent pandemic’: breakthrough study puts first long COVID treatment on horizon

09 April 2025

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COVID-19 is caused by the SARS-CoV-2 virus. This image shows antibodies (shown in orange and purple) binding to ‘spike proteins’ on the surface of SARS-CoV-2 virus (shown in teal and yellow). Spike proteins are critical for SARS-CoV-2 to enter human cells, and this can be blocked by specific antibodies – breaking the infection cycle. Credit: WEHI

Researchers have shown a new drug compound can prevent long COVID symptoms in mice – a landmark finding that could lead to a future treatment for the debilitating condition.

The world-first study found mice treated with the antiviral compound, developed by a multidisciplinary research team at WEHI, were protected from long term brain and lung dysfunction – key symptoms of long COVID.

Researchers hope the unprecedented results could lead to clinical trials and the first treatment for the disease in the future.

At a glance

WEHI researchers have developed a drug compound that can protect mice from contracting long COVID symptoms.

The world-first study also found the compound can treat acute COVID with better efficacy than Paxlovid – the leading treatment currently approved for COVID-19.

It’s hoped the results could lead to clinical trials and an oral treatment for long COVID in the future.

Long COVID, also known as post-acute sequelae of COVID-19 (PASC), is a chronic condition characterised by symptoms that last for weeks or months after contracting COVID-19.

It is a significant health burden that remains poorly understood – with symptoms ranging from breathing difficulties, brain fog and chronic fatigue.

Despite millions of people worldwide reporting these symptoms, the cause of long COVID remains largely unknown and there is no approved treatment for the disease.

Corresponding author and WEHI Laboratory Head, Dr Marcel Doerflinger, said the landmark results could be a turning point in the hunt for treatments to support people at risk of developing this condition.

“With 5% of people who contract COVID-19 going on to develop long COVID, the disease has morphed into a silent pandemic where millions are battling symptoms with more questions than answers,” Dr Doerflinger, said.

“Our pre-clinical studies have achieved something no currently approved therapy has done to date – preventing the most debilitating symptoms of long COVID in mice.

“While more research is needed to develop a drug that can be used in humans, seeing these milestone results in the unique mouse models developed at WEHI suggests this could be a real possibility in the future, which is incredibly exciting.”

L-R: Dr Shane Devine, Dr Marcel Doerflinger and Professor David Komander looking at a PCR machine – a lab device that enables scientists to detect tiny amounts of virus taken from a sample. The data generated from this machine found the novel compound developed by WEHI researchers to be highly efficacious in suppressing the SARS-CoV-2 virus in mouse models. Credit: WEHI 

Landmark discovery

While currently approved therapies for COVID-19 like Paxlovid target a critical coronavirus protein known as Mpro, WEHI researchers identified another protein, termed PLpro as a promising drug target in 2020.

Professor David Komander has spent over 15 years studying the family of proteins that includes PLpro and co-led the large, multidisciplinary WEHI team that spearheaded the discovery of new PLpro inhibitors.

To find a new drug compound that could target this critical protein, the team turned to the National Drug Discovery Centre (NDDC), headquartered at WEHI.

“Existing drugs had hit several hurdles to be effective in blocking PLpro in cells – our team wanted to see if we could find new ones capable of overcoming these barriers,” Prof Komander, a corresponding author and Division Head at WEHI, said.

“In order to do this, we screened over 400,000 compounds to see if we could uncover novel drug-like molecules that had potential against this protein.

“To have identified a drug target and then develop a novel drug compound against it in less than five years is an incredible feat that would have been impossible without the advanced technologies, speed and scale of the NDDC and multidisciplinary team at WEHI.”

Pictured: a mouse lung treated with a drug similar to Paxlovid (left) and a mouse lung treated with the compound developed at WEHI (right). The dark red is indicative of lung damage and inflammation in mice during the long COVID stage of disease. The lung on the right is healthier, showing the WEHI compound’s boosted efficacy.

Boosted efficacy

Dr Shane Devine, a co-first and corresponding author on the paper, said the team also found their novel compound can potentially treat acute COVID better than currently available antivirals for the
disease.

“Our study has provided the first evidence to prove PLpro is a powerful new drug target for COVID-19treatments, while also showing its potential ability to treat the virus with unprecedented efficacy,” Dr Devine said.

Paxlovid is the leading COVID-19 treatment, but is currently only recommended for people who areconsidered at risk of severe disease.

A key limitation of this treatment is that it requires two compounds to interact with each other for the treatment to be effective – meaning it can also interfere with many other medications.

“Paxlovid and other antivirals in the market target Mpro and have these same issues, highlighting the urgent need for more research to enhance COVID-19 treatments that can provide greater access to more patients,” Dr Devine said.

“The SARS-CoV-2 virus also continues to mutate, meaning it’s only a matter of time until Paxlovid will no longer work.

“Our findings could lead to a future drug to help close these critical gaps.”

The project will continue collaborating with the Centre for Drug Candidate Optimisation (CDCO) and the Monash Institute of Pharmaceutical Sciences (MIPS) to evaluate the biopharmaceutical properties of this antiviral compound.

The research is supported by the Medical Research Future Fund, the Wellcome Trust and generous philanthropic donations for COVID research and translation.

Chief Investigators: Professor Guillaume Lessene, Dr Marcel Doerflinger and Professor David Komander.
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Header image:COVID-19 is caused by the SARS-CoV-2 virus. This image shows antibodies (shown in orange and purple) binding to ‘spike proteins’ on the surface of SARS-CoV-2 virus (shown in teal and yellow). Spike proteins are critical for SARS-CoV-2 to enter human cells, and this can be blocked by specific antibodies – breaking the infection cycle.