Friday 07 September, 2001
Aids vaccine hope
It is the holy grail of Aids research. One small jab, or maybe even a pill and you need never worry about catching the disease which has so far killed 22 million people worldwide.
Attempts to develop Aids vaccines began more than ten years ago, but they have all so far failed - due to the ability of the virus to mutate or change its shape. But as BBC Science reports, there is now new hope.
Vaccine trials
In March this year Pamela Mandela became one of 18 Kenyan volunteers to be injected with a vaccine containing part of the genetic material of HIV.
She is not HIV positive but she lives in Kenya where more than 2 million people have the virus and this is her way of tackling the problem. She comments:
| ‘I fear Aids, but I also hate Aids. Being one of the first volunteers, I am fighting back at HIV and Aids - and not just fearing.’ | |
The story of this vaccine begins with an extraordinary group of Nairobi prostitutes.
Dr Andrew McMichael, who heads the international research team that is developing the vaccine, explains why they were the key to the project:
‘Those who live in a particular slum area called Mujego have a very high rate of infection. So 90% of the women are infected, which is terrible, but of the 10% who aren't, about half of those are resistant to infection. They've been exposed for many years, they have incredibly high exposure but they don't become infected.’
Immunity
The apparent immunity of this group of women to the HIV virus intrigued Kenyan researchers like Omu Anzala from the University of Nairobi medical school:
‘The question is what is really happening here? Why are these women remaining HIV negative? And yet when we follow them through the clinics we see them coming in with all manner of other sexually transmitted diseases.’
Vaccines designed to tackle HIV have been developed before, but they've all failed. In all cases the HIV virus was able to adapt and withstand the vaccine.
An international research team was set up to examine the blood of the Kenyan women to try to work out why they were immune. Andrew McMichael examined this blood in his laboratory at Oxford University in the UK.
He explains:
| ‘We found that these women actually make killer T cell responses to HIV and we've argued that this is what’s protecting them from infection.’ | |
Killer T cells
Killer T cells are blood cells responsible for attacking cells infected with viruses. They do this by picking out a very specific part of the virus exposed on the surface of infected cells.
Last year the research team announced they had found the part of the HIV virus that the women's T cells attacked, from this they developed their vaccine, which went into human trials earlier this year. McMichael explains:
‘We put virus proteins, not the whole virus, inside cells and allow those cells to process the virus proteins in a way that will stimulate killer T cells, which have a rather curious way of seeing virus products on the cell surface.’
‘If we can mimic that then we can stimulate killer T cells and we have found ways of doing that that look pretty effective.’
Human trials
The human trials are still in their early stages. So far they have concentrated on seeing if the vaccine is safe - the biggest fear being that it could accidentally trigger HIV.
Omu Anzala says, within their limited scope, these trials are going well:
‘We have not seen any major side effects, but the kind of side effects we have seen are like headache and fever are normal with any drug.’
If all goes to plan a major trial involving thousands of people will take place in about three years.
This will be a very complex venture involving finding people who are at a high risk of contacting HIV. In addition to using the active vaccine, some of the volunteers will be treated with an inactive or placebo drug to rule out any psychological effects.
Scientists are convinced that in terms of drug treatments for HIV, vaccines are the way forward. And it’s economic arguments, which are now driving research.
While the initial cost of developing vaccines may be high it is minimal when compared to the projected costs of treating the symptoms of the worlds estimated 36 million HIV infected people.
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| Racism and Aids |
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According to Dr Peter Piot, the head of the United Nations' Aids programme, racial prejudice is helping the spread of the disease around the world.
Addressing delegates at the World Conference Against Racism in Durban, South Africa, Dr Piot told said that if the Aids epidemic had centred on Europe, rather than Africa, and had affected predominantly white people, the response to it would have been faster and more generous.
There are about 36 million people infected with HIV around the world, 25.3 of whom live in Africa, according to UNAIDS. |
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