Putting HTLV-1 on the map

Hearing that the World Health Organization (WHO) has declared a new threatening pathogen wouldn’t normally be cause for celebration. But for University of Melbourne Professor Damian Purcell, a Laboratory Head at the Doherty Institute, the classification of HTLV-1 as Threatening Pathogen to Humans by the WHO followed years of hard work and advocacy to have this deadly disease recognised.  

HTLV-1, the Human T-cell lymphtrophic virus, affects up to 10 million people worldwide and is endemic in remote Aboriginal communities. The virus’s tendency to slip under the radar has allowed it to run rampant in some communities, such as Indigenous Australian living in remote areas where it affects more than 45 percent of people. There is no treatment or cure.  

From a similar family of viruses as HIV, infection can lead to neurological diseases and blood cancers. As the virus replicates, it suppresses the protective activity of the immune system.  

The viruses ability to exist, largely anonymously, drove a team of researchers and advocates from across the globe to campaign for awareness. 

The campaign to put HTLV-1 on the map began back in 2017 following a special symposium on HTLV-1 at the Global Virus Network’s (GVN) 9th International Meeting at the Doherty Institute, when a team of researchers and advocates from across the globe penned an open letter to the WHO, published in The Lancet, calling for an end to HTLV-1. 

It was the first big step.  

Members of the GVN’s HTLV-1 Task Force then petitioned Ministers of Health around the globe to call on the WHO to recognise HTLV-1, and in 2018 the WHO invited the network to assemble a team to provide a review on the issue.  

Three years later, on the Thursday, 15 April 2021, the WHO formally classified the virus. 

For Professor Purcell, one of the signatories to the original letter and a member of the GVN’s HTLV-1 Task Force, the announcement was welcomed progress.  

“It came at the end of the 20^th International Conference on Human Retrovirology which we were hosting in Melbourne. Dr Zsuzsanna Jakab, the Deputy Director-General of the WHO recorded a video message for us which we were able to share with the delegates, this is an important step in advancing the understanding of HTLV-1 and reducing the burden of disease it causes.  

"It felt amazing that at it was finally being recognised at the top level of the WHO and that they had given it a home in the WHO structure, classifying it into the HIV, hepatitis and sexually transmitted infections portfolio.  

"Australia has the highest rates of HTLV-1 infection anywhere in the world. And yet it is still not listed as a notifiable disease, true infection rates remain unknown."

“Specifically for Australia, we have all of the key components required for an effective response to this virus – indigenous clinical leadership; the medical research skills and capacity; and two forthcoming developments in treatment and vaccine development. 

“However, it wasn’t even on the table as a major issue, in Australia or globally and therefore, there was no desire to accelerate research and implement the strategies.” 

Professor Purcell is hopeful that the classification by the WHO will help shed light on the situation and encourage proactive steps towards combating the virus.  

You need to look no further than its sister virus, HIV, to see how beneficial high profile can be.  

“Thanks to global investment and public health interventions, great advances have been made in the fight against HIV-1 and we need the same approach to be applied to HTLV-1,” said Professor Purcell.  

“Things like combination antiviral drugs – these interventions haven’t even been investigated or initiated with HIV. It also looks like vaccines might be much more achievable in the setting HTLV-1 than HIV. We need to take what we have learnt researching and investing in HIV vaccines and apply it to HTLV-1, it is all relevant.  

HTLV-1 presents a complex pattern of disease. 

“While HTLV-1 infections are considered to be inconsequential at first, we have shown that in every infected person this virus causes insidious lifelong damage to normal immune function,” explains Professor Purcell. 

And with the disease not notifiable, this is likely just the tip of the iceberg.  

“We know some things that are directly caused by HTLV-1, like T cell leukemia. But as we get more data, better quality data, we are going to understand there are many more conditions that are linked,” says Professor Purcell. 

“People at risk from HTLV-1 deserve biomedical tools against this virus similar to those that provided game-changing therapeutic and prevention options for the other blood-born persistent viral infections like HIV and the HBV and HCV hepatitis viruses.”