Scientists have now gained new insights into a cancer-causing virus.
A virus, called human T-cell leukemia virus type 1 (HTLV-1), is known to contribute to leukemia and lymphoma. HTLV-1 is a retrovirus, and like another retrovirus HIV, it also affects T cells, which are vital cells in the immune system. Although HTLV-1 in most cases doesn't trigger signs and symptoms, some individuals infected with the virus develop cancers such as adult T-cell leukemia (ATL).
In a new study described in the Journal of Virology, a team consisting of scientists from the University of Minnesota and University of Delaware focused on a critical structural protein in HTLV-1 that is responsible for virus particle assembly and release, known as the Gag protein
. They introduced mutations into Gag and explored how these mutants could affect the production of HTLV-1 particles. They found several critical amino acid residues in the structurally conserved capsid domain of Gag, which were needed to produce virus particles.
The discovery greatly deepens the understanding of the importance of the structure of Gag in virus particle assembly. The role of HTLV-1 Gag is distinct from that of HIV-1 and other retroviruses studied to date. The production of new viral particles is important for a virus to establish its infection in host cells. Thus, the discovery would have significant implications in studying the biology of HTLV-1 and developing antiviral strategies.
According to study senior author Louis Mansky at the University of Minnesota, our understanding of HTLV-1 is far from complete, and more investigation into how new viral particles are produced from infected host cells is needed.
In remote regions of central Australia, HTLV-1 infection rate is higher than 40% in adults, and the indigenous communities are most affected. This high rate of HTLV-1 has attracted scientists' attention. Recently, a coalition of scientists, activists, and researchers in this field wrote to the World Health Organisation (WHO) to plead for action to fight HTLV-1.
HTLV-1 is a "distant cousin" of HIV. The two viruses have something in common. For example, like HIV, HTLV-1 can also be transmitted through sexual contact, blood transfusions, and mother-to-child transmission. However, there are differences between HIV and HTLV-1. For instance, HTLV-1 is highly contagious but is not as easily transmitted as HIV. Besides, only some of the HTLV-1-infected people develop HTLV-1-associated diseases. Due to these differences, HTLV-1 is less well-known, compared with HIV.
In addition to leukemia, HTLV-1 also causes other severe complications, including kidney failure, lung disease, inflammation of the spinal cord that may result in paralysis, and other infections. It's estimated that HTLV-1 infects up to 20 million people worldwide. But this number could be bigger because there is a lack of awareness and testing for HTLV-1.
HTLV-1 was first detected and isolated in 1979 and the discovery was published in 1980. In 1984, HIV was first discovered. HIV has become a global epidemic and attracted the whole world's attention. Possibly due to this reason, HTLV-1 has been neglected by the global research community for a long time. There's been little research to develop treatments or a vaccine for HTLV-1. That's why 60 representatives from 26 countries signed a letter recently to tell WHO it's urgent to eradicate HTLV-1.