Why not eliminate HTLV-1 while eliminating HIV-1? We need HTLV-1 PEP/PrEP clinical trials

Posted on November 28, 2023   by Dr Goedele N. Maertens and Dr Fabiola Martin

As a former elected member of the Virology Division, it has been my honour to help shape the scientific content of the Annual Conference for the past three years. From close by I have witnessed the amazing science that is done by all members of our Society, the supporting network that is built by and for the members of the Society. Microbes affect us all, the recent Covid pandemic made that very clear to us all. Here, Dr Fabiola Martin and I ask for your support in our call to include a not so well known, yet disabling and often deadly virus, human T-lymphotropic virus-1 (HTLV-1), to be included in HIV-1 pre-exposure clinical trials. 

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HTLV-1 PrEP Open Letter to Gilead & ViiV

Human T Lymphotropic/Leukaemia Virus-1 (HTLV-1) is a sexually transmitted infection (STI) closely related to human immunodeficiency virus-1 (HIV-1). HTLV-1 causes chronic infection, can be transmitted from mother to baby and is associated with significant disease burden and mortality, preceded by years of suffering and poor quality of life for victims.   

Therefore, HTLV-1 is one of the 2030 elimination targets of the World Health Organization’s global STI elimination strategy.  

Although there is currently no drug or vaccine available to cure HTLV-1, we now know that the very same drugs that effectively treat patients with HIV or prevent people from getting HIV-1, called HIV PrEP, also prevent the transmission of HTLV-1 in our laboratory testing (Reviewed in Bradshaw and Taylor, Frontiers in Medicine 2022). We believe that these compounds are likely to block the transmission from mother to child. 

It is well known that many HIV PrEP clinical trials are conducted in countries where HTLV-1 is common. So, by adding in HTLV-1 testing to these HIV-PrEP trials we could measure if the HIV PrEP drugs also prevent HTLV-1 transmission. The beauty of such an outcome would be that these HIV-1 drugs are already licensed to be used in humans.  

Therefore, in our open letter to the pharmaceutical companies Gilead and ViiV we are calling for the inclusion of the outcome ‘HTLV-1 transmission incidence’ into their HIV-1 clinical trials when conducted in HTLV-1 endemic regions. 

We and our patients know that this inclusion is not only feasible and of top-priority, but unethical if left ignored.  

It is our moral obligation to include HTLV-1 in these HIV-1 clinical trials.   

Including HTLV-1 in these HIV-1 clinical trials will be beneficial for two reasons:  

  1. Obtaining critical information through research is essential in finding new ways to halt transmission between patients and will contribute significantly to the body of literature. 
  2. These trials will provide the necessary framework for testing these drugs. It is a moral imperative to incorporate HTLV-1 testing into the trials, as it empowers the parents involved in the study to take every possible measure to prevent transmission to their children. This approach ensures that fathers and mothers living with HTLV-1 can sleep peacefully at night, knowing they have done everything in their power to protect their children from contracting HTLV-1.

On November 10, World HTLV day, we made this letter available to the public. We are asking you to support us with your signature and to share the HTLV-1 PrEP Open Letter widely. We and our patients, and all people who may become infected with HTLV-1 rely on your support. 



Dr Fabiola Martin and Dr Goedele N. Maertens 

Dr Fabiola Martin, Sexual Health Specialist, Senior Clinical Lecturer, University of Queensland, Brisbane, UQ 

Dr Goedele N. Maertens, Reader in Molecular Virology, Imperial College London, UK 

This blog was republished on the Microbiology Society website with permission from Dr Fabiola Martin, Dr Goedele N. Maertens and Imperial College London 

The original blog can be found here.