Public health impact and implications for future actions: WHO global consultation on the human T-lymphotropic virus type 1, Tokyo, Japan, 13-15 November 2019

The human T-lymphotropic virus type 1 (HTLV-1, also known as the human T-cell leukaemia virus type 1), was the first oncogenic human retrovirus discovered 40 years ago. It was shown to be the cause of an aggressive haematological malignancy known as adult T-cell leukaemia/lymphoma (ATL). Transmission of HTLV-1 occurs when the viral RNA genome from infected donor cells transfers and permanently integrates a copy of proviral DNA into the cells of a recipient host. This results in lifelong infection of the new host.