A study co-led by WEHI and the Peter Doherty Institute for Infection and Immunity has found that existing HIV drugs can suppress transmission of the HTLV-1 virus in mice.
Human T-cell leukaemia virus type 1 (HTLV-1) is a virus that infects the same cell type as HIV – T cells, a type of blood immune cell that helps the body fight off infections.
A small proportion of people infected with HTLV-1 after a long duration of infection develop serious diseases, such as adult T-cell leukemia and spinal cord inflammation. Around 10 million people globally live with the life-threatening virus HTLV-1. Yet it remains a poorly understood disease that currently has no preventative treatments and no cure.
The new study, published in Cell, identifies a new drug target that could lead to the elimination of HTLV-1-positive cells from individuals with an established infection, thereby preventing disease progression.
Co-lead author and WEHI laboratory head Dr Marcel Doerflinger said the promising results of the new study could help find a desperately needed treatment and prevention strategy for one of the most neglected viruses in the world.
“Our study marks the first time any research group has been able to suppress this virus in a living organism,” said Dr Doerflinger.
“As HTLV-1 symptoms can take decades to appear, by the time a person knows they have the infection the immune damage is already in full swing.
“Suppressing the virus at transmission would allow us to stop it before it has the chance to cause irreversible damage to immune function, leading to disease and a premature death.”
In a 10-year research effort, the team isolated the virus. It developed a world-first humanised mouse model for HTLV-1, enabling them to study how the virus behaves in a living organism with a human-like immune system.
The mice were transplanted with human immune cells that are susceptible to HTLV-1 infections, including Australia’s genetically novel HTLV-1 strain. International and Australian strains equally caused leukaemia and inflammatory lung disease in these human immune system mice.
The mice were then treated with tenofovir and dolutegravir – two antiviral therapies currently approved to silence HIV and prevent AIDS.
“What’s most exciting is that these antivirals are already in use for millions of HIV patients, meaning there’s a direct path for the clinical translation of our findings,” said Dr Doerflinger.
“We won’t have to start from scratch because we already know these drugs are safe and effective. And now we’ve shown that their use can very likely be extended to HTLV-1.”
The researchers also discovered that human cells containing HTLV-1 could be selectively killed when mice were treated with HIV drugs in combination with another therapy inhibiting a protein (MCL-1) known to help rogue cells stay alive.
The team is now leveraging precision RNA therapies to develop new ways to target MCL-1 and establish combination treatments that can be clinically tested, which they believe could offer a promising curative strategy for HTLV-1.