What are HIV and AIDS?
What are HIV and AIDS?
HIV, or human immunodeficiency virus, is an infection that is passed between people by unprotected sex or by sharing a needle or syringe to inject drugs with someone who is infected. The virus often stays inactive in the blood for a long time, even years, before causing any symptoms. But eventually it begins to destroy immune system cells called CD4 cells.
As a result, the patient’s immune system gradually loses the ability to protect them against other illnesses and infections. When this happens, the disease is known as AIDS, or acquired immunodeficiency syndrome. Once HIV infection develops into AIDS, the sufferer is open to many infections, including thrush, pneumonia and tuberculosis, and infections of the brain, eye, skin and stomach. Patients often develop persistent diarrhoea and lose weight as well.
The virus works by invading a CD4 cell and making billions of new copies of itself. It then kills the ‘host’ cell and releases the new copies of itself which can go on to infect and kill other CD4 cells. There are estimated to be almost 60,000 people in the UK who are infected with HIV, including a third who may not know they have the virus. But rates of HIV/AIDS are much higher in developing countries – for instance, in some parts of Africa one in four people are HIV-positive.
A snapshot of MRC research into HIV and AIDS
MRC scientists are currently carrying out several major studies into preventing and treating HIV/AIDS. Some of this work is based at our units in The Gambia and Uganda, while teams of MRC researchers in the UK are also working hard to find ways to combat the epidemic. Here are some examples:
- The Microbicide Development Programme is a partnership set up between the MRC and the UK Department for International Development to develop vaginal microbicides to prevent HIV transmission. Coordinated by the MRC Clinical Trials Unit in London, the researchers have recruited 10,000 healthy women in Uganda and South Africa to test a potential microbicide gel for three to four years.
- MRC researchers are carrying out a five-year study to test the effectiveness of anti-retroviral HIV drugs in rural Africa. The lab tests usually used to monitor such treatment are unavailable in these areas, so it will rely on doctors’ observations alone. A total of 3,300 volunteers, who will receive treatment during and after the trial, have been selected from two sites in Uganda and one in Zimbabwe.
- Working at the molecular level, Professor Michael Malim of King’s College London is studying how the HIV virus infects human cells and what causes it to become resistant to drug treatment.
- At University College London, Professor Caroline Sabin is studying databases of anonymous information about HIV patients in the UK to find out about rates of drug resistance and at what point in treatment the virus tends to become resistant to different drugs. She aims to develop a mathematical model to estimate when current treatments will no longer be effective and ways to prevent this happening.
- Professor Frances Gotch at Imperial College London is testing two possible HIV vaccines. These new vaccines might make it possible to delay or interrupt antiretroviral drug treatment, or increase the time it remains effective in individual patients.
- The MRC Viral Diseases Programme in The Gambia involves population-based studies of different groups of people with and without HIV infection. It including finding out how antiretroviral drugs can be effectively used and a study of thousands of people infected with HIV-2 – a relatively uncommon form of the virus that is less easily transmitted.
- The MRC/Ugandan Viral Research Institute is using a wide variety of research tools to tackle the HIV/AIDS epidemic. This work includes finding out how antiretroviral drugs can be used effectively in Africa, and a study of thousands of people infected with HIV-2 to understand why this relatively uncommon form of the virus is less easily transmitted than HIV-1, which could help lead to the development of new drugs or vaccines.