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Understanding HTLV-1

HTLV-1, like its distant cousin - HIV, is a blood-borne and sexually transmitted virus, also passed from mother to child through breastfeeding. It causes a lifelong infection of immune cells and is associated with a wide range of serious diseases, including T-cell leukemia, neurological diseases and chronic inflammatory diseases.  

The University of Melbourne’s Dr Ashley Hirons, Research Officer at the Doherty Institute, explained that, unlike HIV, HTLV-1 does not destroy infected cells, but instead promotes the growth and survival of poorly functioning infected cells that readily evade immune detection. 

“This virus remains in the body for life and can impact long-term health, even in people with no obvious symptoms,” said Dr Hirons. 

Like HIV, HTLV-1 has no cure. But unlike other blood-borne viruses such as HIV, hepatitis B and hepatitis C, there are neither effective antiviral treatments, nor rapid diagnostics for remote settings or preventive vaccines for HTLV-1.  

Challenges and advocacy for HTLV-1

Despite its prevalence and health consequences, HTLV-1 is not widely known and remains one of the most neglected viruses in research, public health policy and awareness. While HIV has benefitted from vast amounts of research and funding, HTLV-1 lacks comparable resources, resulting in minimal advancement in treatment. 

In many countries, routine screening is not available and infections often go undetected.  

“HTLV-1 infections are often diagnosed incidentally, or after a disease has progressed, due to limited testing protocols, particularly in Australia. This contributes to a higher risk of transmission and delays crucial support and options for managing the associated conditions,” said Dr Hirons. 

The University of Melbourne’s Professor Damian Purcell, Head of Molecular Virology Laboratory at the Doherty Institute, has worked to put HTLV-1 on the map and advance our knowledge of the virus through his research. For Professor Purcell, raising awareness is crucial to encouraging testing, preventing transmission and reducing the stigma associated with the virus. 

“Enhanced knowledge and awareness of HTLV-1 among healthcare professionals and the public can drive earlier detection, boost research initiatives and ultimately lead to better health outcomes for those affected by the virus,” said Professor Purcell. 

Professor Purcell is a major contributor to a campaign launched in 2018, a year after the 9th Global Virus Network International Meeting put the spotlight on HTLV-1. Researchers and advocates wrote an open letter to the WHO, published in The Lancet, calling for action to eradicate the virus.  

They then petitioned health ministers globally, prompting the WHO to review the issue. In 2021, following years of advocacy by international researchers, the WHO formally recognised HTLV-1 as a Threatening Pathogen to Humans, classifying it into the HIV, hepatitis and sexually transmitted infections portfolio.  

A coordinated approach to ending HTLV

Despite this win on a global scale, more than three decades after the virus was first identified in Central Australia, no harmonised public health response has been implemented to reduce transmission in remote communities. 

“HTVL-1 is not going away, and it causes serious diseases in a high number of people. We owe it to the communities affected to focus our effort on the development of solutions to prevent, treat, cure and eliminate the virus,” Professor Purcell said. 

The Doherty Institute, in collaboration with organisations in the US and Japan, is working to raise awareness and advance vaccine research efforts on HTLV-1. In 2022, the Institute signed an agreement with Moderna to accelerate vaccine development for neglected regionally important infectious diseases, including HTLV-1.  

A recent study, led by the Doherty Institute and published in Retrovirology, stressed the importance of understanding the genetic make-up of the various HTLV-1 subtypes around the world. The research found that HTLV-1 subtype-C, prevalent in Central Australia, has key genetic differences compared to the more globally spread subtype-A, underscoring the need for further research to understand the implications on viral pathogenesis and transmission.  

Dr Hirons also believes that by raising awareness among policymakers and the healthcare community about the virus, countries like Australia can build a healthcare infrastructure that includes better surveillance, more robust diagnostics, transmission prevention strategies and support framework for those living with HTLV-1. 

“By raising our collective voices, we can ensure that HTLV-1 becomes a priority on both the Australian and global health agenda, providing hope and support to millions living with this virus,” she said.