FRUSTRATION AT being unable to help Aids patients drove Kenyan surgeon Dr Pamela Mandela Idenya to become the first Kenyan to receive a trial Aids vaccine in public.

"I joined the medical profession to alleviate human suffering, but with Aids, I often find myself not able to," the 31-year-old ear, nose and throat specialist said on Wednesday last week after being injected with the test vaccine.

"I fear Aids, but I also hate the havoc it is wreaking. By being one of the first volunteers, I am fighting back."

Pamela is the fourth Kenyan to receive the trial vaccine, but so far the only one to inform the public about it. Like all other subjects involved in the first phase of the trials, Pamela is HIV-negative and is considered at low risk of contracting the Aids virus.

"I hope my example will encourage other Kenyans to volunteer for the trials," she said on Thursday. "An effective vaccine offers the best hope in the war against Aids, especially given that the high cost of antiretrovirals makes them virtually inaccessible for most people in the developing world."

About 60 Kenyans are expected to be involved in the trials. Subjects like Pamela have to satisfy strict inclusion criteria, including being HIV-negative, being in good general health and being free from chronic illness such as diabetes or heart disease.

The trial vaccine was developed by Kenyan and British scientists following the observation, in the mid 1980s, that a group of prostitutes operating at Nairobi's Majengo slum were immune to HIV, the virus which causes Aids.

Subsequent immunological investigations revealed that the prostitutes had above normal levels of cytotoxic or killer T-cells, which are an important component of the body's arsenal against the Aids virus.

The researchers postulated that a vaccine which stimulated the body to produce the killer -T cells could protect uninfected people against HIV.

According to Dr Omu Anzala, the manager of the team of Kenyan researchers involved in the studies, the vaccine comes in two parts. The first is a naked DNA component which encodes the parts of the Aids virus that stimulate the production of killer-T cells. When administered to humans, scientists hope, the component will prime the body to produce the T-cells in healthy people. 

The second is the same DNA put into a Modified Vaccinia Virus (MVA), which is used as a carrier. This part of the vaccine is intended to boost the immune response elicited by the naked DNA component.

Pilot lots of the DNA vaccine, The EastAfrican established, were manufactured by the British company, Cobra Pharmaceuticals, and the MVA by a German firm called IDT.

Because subjects involved in the trials will not receive the actual Aids virus itself, researchers say, they will be at little risk of contracting the killer disease. 

The test vaccine is designed to protect against strain A of HIV, which causes at least 70 per cent of all infections in East Africa. Virtually all of the other vaccines under development are for HIV type B, which is the most common strain in northern America and Europe.

According to Dr Anzala, the trials currently taking place in Kenya are the first in a three phase programme to find out whether the vaccine is safe and effective. The first phase, Dr Anzala says, is meant to specifically test the safety of the vaccine and its effects on the human body. 

Dr Anzala says phase II trials, to check the immune response, will be carried out on people considered to have a relatively higher risk of HIV infection than those in phase I, while phase III, lasting three or four years and using very high risk subjects such as commercial sex workers and truck drivers, will establish the effectiveness of the vaccine in protecting against HIV.