World AIDS Day is an international day dedicated to raising awareness of AIDS (acquired immunodeficiency syndrome) and the virus that causes it – HIV (human immunodeficiency virus). It is a chance to support the over 105,000 people who live with HIV in the UK, and 38 million who live with it worldwide. It’s also an opportunity commemorate the 40 million who have died from an AIDS-related illness.
Ongoing HIV research at the Francis Crick Institute aims to better characterise HIV proteins through structural and molecular biology. Despite over 40 years of research into HIV, there are still aspects that are not well characterised. By understanding HIV replication and its interaction with factors inside the host cell, we can better identify drug and vaccine targets for preventing and treating infection.
HIV is a retrovirus, a kind of virus that carries single-stranded RNA instead of DNA. Infected cells read this RNA and turn into DNA, inserting it into their own DNA and causing the cell to produce more retroviruses. Scientists in our Retrovirus-Host Interactions Laboratory and Retroviral Replication Laboratory are looking at how retroviruses infect cells, how the viruses multiply when they get inside a cell, and which proteins the viruses interact with along the way.
As there is currently no cure or vaccine for HIV, the only way to treat the virus is through antiretroviral therapy (ART). If taken every day, exactly as prescribed, ART can reduce the amount of HIV in the blood - the ‘viral load’ - to a very low level. This is known as viral suppression, and it helps to keep you healthy and prevent illness.
If your viral load is so low that it does not show up in a standard lab test, this is called having an undetectable viral load. Almost everyone who takes ART daily can reach an undetectable viral load after six months of treatment, eventually living a healthy life with no risk of transmitting HIV.
Researchers at the Crick found that ART also reduces the risk of developing active tuberculosis (TB) in people infected with HIV-1. TB is one of the leading causes of death among people living with HIV, so the findings highlight the additional benefits of ensuring people living with HIV have access to ART.
There are two different ways of looking at a cure for HIV – a ‘sterilising cure’ and a ‘functional cure’. A sterilising cure means that there is no trace of HIV left in the body, while a functional cure means that a person remains undetectable without medication, although a ‘latent’ form of the virus might still exist in their body in areas called ‘reservoirs’.
One of the key challenges in HIV research is finding a way to get rid of these reservoirs. The two main methods under investigation are called ‘shock-and-kill’ and ‘block-and-lock’. In ‘shock-and-kill’, the dormant virus is woken up so that it can be treated with antiviral drugs, whereas the ‘block-and-lock’ method aims to permanently silence the dormant virus. There has been some progress in these areas, but we still don’t have a way to eliminate the reservoirs completely.
Bone marrow transplants have also shown some success as treatments for HIV, leaving three patients between 2008 and 2020 with no trace of the virus in their body. However, bone marrow transplants are risky and often impractical.
As eliminating the reservoirs remains challenging, and bone marrow transplants aren’t likely to be practical on a wide scale, a functional cure could be a more achievable short-term goal. Although this means that the person would still harbour the virus, it would be possible to control it long-term without antiretroviral drugs. Studies involving antibody treatments or different antiretroviral treatments have shown some remission or long-term suppression, and there are some promising signs.
A 2021 report found that more than 4 in 5 people believed there was still a risk of someone on effective HIV treatment passing on HIV through sex.
The stigma associated with an HIV diagnosis is amplified by intersecting prejudices and discrimination raising additional barriers to treatment and prevention for many of the key populations at risk of HIV infection including men who have sex with men, Black African populations, people who inject drugs, people in prisons, sex workers, transgender people, and migrants.
