HIV Immunity - Salome is a human specimen of potentially incalculable value

[Snowy Owl]

The search for Salome's secret
By William Langley in Nairobi

http://www.telegraph.co.uk/news/main.../wsalome16.xml

The place that Salome Simon calls home is a rickety, spearmint-painted shack with a listing tin roof, under which are squeezed two beds offering strikingly different comfort levels. One is a pink-curtained affair of almost Barbara Cartlandesque splendour - the other is low, plain and hard, and it is where Salome's work as a 50p-a-trick Kenyan prostitute is done.
<!--MPU STOPPED BY MEDIA --> The local punters are not the only ones with an interest in her services. To Western scientists and medical researchers, Salome is a human specimen of potentially incalculable value. Despite plying her trade for more than two decades in a country ravaged by Aids, she has never contracted HIV, and every credible study of her case points towards her being immune to it.


If the secret of her immunity could be identified and its ingredients reproduced in the laboratory, the world might be vastly closer to developing an effective Aids vaccine. But Salome's body has chosen not to surrender its mysteries easily. Dr Larry Gelmon, the co-ordinator of a Canadian-led research team examining her case - and those of a small number of other apparently Aids-resistant Kenyan prostitutes - says: "It's baffling, it's tantalising, it's exasperating, but we are certain the answer's here somewhere."
Kenya's Aids rate is one of the world's highest. In recent years, the figure has been as high as 25 per cent of the general population, though estimates are now at 15 per cent. Among the women who sell sex, the levels of infection are 80 per cent. Dozens of those whom Salome has worked alongside have died through the years, yet she remains, enigmatically, uninfected.
Dressed in a bright print wrap and black canvas sneakers, Salome, 45, looks little different from tens of thousands of other women in the teeming Nairobi suburb of Majengo.

The word means "slum" in Swahili, and never was anywhere more appropriately named; the unmade streets are narrow and treacherous, the tiny houses dilapidated, the air malodorous, the atmosphere - at least for outsiders - menacing. Here, for more than 20 years, Salome has worked at a prodigious rate.
On an average day, she might entertain five or six clients. On a good day, 10. In the course of her career, she has probably had sex more than 50,000 times. The encounters are basic - lasting around two minutes each - but they earn her 7,000 Kenyan shillings (&#163;65) a month, which, in this neighbourhood, amounts to a decent wage.

"I don't like the work, but I am a businesswoman," she tells me, with a hearty chortle, "and I have to think about the money. I tried working on a stall, but it wasn't so good." She appears bemused by the scientists' interest in her, but says that, if she becomes famous, she would like to leave Majengo and buy a big house somewhere else.
Evidence of the immunity phenomenon first emerged in the late 1980s when a team of Canadian medical researchers, studying sexually transmitted infections in Nairobi, noticed that a small number of local prostitutes - while susceptible to other venereal diseases, such as syphilis and gonorrhoea - were not contracting Human Immuno-deficiency Virus.
At this time, Aids was beginning its sweep across sub-Saharan Africa, changing the world's perception of it as a "gay plague", and leaving millions dead.

Prostitution in Kenya is a rough-and-ready business, mostly practised at rural truckstops and in poor homes, like Salome's. Such polite, First World notions as "safe sex" were slow to arrive. "Nobody used condoms here," says Dr Elizabeth Ngugi, a community health specialist at Nairobi University. "Kenyan men like their sex nyama kwa nyama - flesh to flesh - and, even when condoms became available, they'd pay more not to use them. So most women were unprotected and the virus spread like wildfire."
Seated on a wooden stool outside her shack - the sign that she is available for business - Salome watched as her fellow prostitutes began to sicken and die. "I knew something bad was happening," she says. "I lost friends and neighbours. Sometimes I wondered why it wasn't happening to me."

Precisely the same question occurred to the team from the University of Manitoba, which had set up a small study base in Majengo. The project's leader, Dr Frank Plummer, now the eminent director of the Centre of Infectious Disease Prevention and Control in Ottawa, was astounded by what he found. "It was clear," he says, "that a small number of these women were basically immune to HIV. It was beyond statistical possibility that they had simply been lucky. Their exposure has been on an enormous scale. Something in their systems is able to recognise and destroy the virus."

But what? And how? And why, if proof of human immunity to Aids is sitting in wattle huts in tumbledown Majengo, has the world at large taken so long to wake up to it?

Only in the past few years has the pace and urgency of the Nairobi research begun to accelerate. Bill Gates's charitable foundation gave a multimillion pound donation last year, and other money has flowed in from organisations around the world, including Britain's Wellcome Trust. New laboratories dedicated to the study have recently opened at Nairobi University. Yet the research is beset with difficulties. HIV, the virus that causes Aids, has proved itself to be a fiendishly clever and endlessly adaptable foe, and the early certainty that science would find a counter to it has long since evaporated.

The women - mostly illiterate and steeped in an essentially peasant culture that holds to its own, closed ways - are not the easiest sample to study. Many are considered unreliable witnesses to their own lives, and they regularly drop out of the project, moving to other towns. Certain clues have, nevertheless, emerged. It appears, for example, that most of the immune women are genetically linked, but these ties produce no definitive pattern or guarantee that immunity will be passed on. One of Salome's daughters recently died of Aids.
It also seems, bizarrely, that the immunity fades if sexual activity ceases. Blood tests have shown that women who take a break from their work, as the Nairobi prostitutes often do on their annual return to their villages, suffer a sharp fall in their immune responses. Several have contracted the virus on resuming business. "The conclusion is that they are best protected when their systems are being constantly challenged," says Dr Plummer. "When there is nothing to fight, the defences come down."

Nor is the women's immunity absolute. When HIV is introduced into samples of their blood, it takes hold as it would normally. Perhaps the most astonishing thing about the Nairobi prostitutes is, therefore, that they seem to be protected only against contracting HIV through sex. "This makes us think," says Dr Richard Lester, an infectious disease specialist attached to the team, "that the key to the immunity may lie in their genital tracts. The virus is entering their bodies, but before it gets into their bloodstream it is being identified and killed.
"Usually in immunology, the first place you look for answers is the blood, and this may have been our mistake. We've been focusing on the wrong thing. There's nothing unusual about these women's blood, but there might be about their vaginas."

A possible explanation is that the women's genital tracts, stimulated by excessive sexual activity, have developed powerful antibodies that can destroy HIV. And, if excessive sexual activity is what a scientist hopes to study, there is nowhere better to look than in the micro-brothels of a Kenyan shanty town.

Salome was raised in Bukoba, a small town in neighbouring Tanzania, where she married, and had three children. After her husband left her, she moved to Nairobi looking for work. Tens of thousands of other poor, rural Africans have the same idea every year, and competition for the few jobs available is tough. "I had my children to feed," she tells me, sitting on the low bed that she jokingly calls "the office". "I needed money, and this work was all I could do."

Gloomy and humid, the one-room shack is 8ft-square, with no electricity, running water or furniture apart from the two beds. She cooks on a tiny paraffin stove, and her only luxury is a portable radio. Ten years ago, she tried to make a living selling shoes on a market stall, but her takings were barely a quarter of what they had been before, and she quickly returned to prostitution. Even so, she considers herself fortunate. Of the 20 or so women who first joined the project, she is believed to be the only one left alive.

Since those early days, other pockets of Aids immunity have been discovered all over the world. The incidence in the general population may be as high as five per cent, but none of these people offers the same dramatic potential for study as the Kenyan prostitutes. "What is unique about these women," says Dr Gelmon, "is that they are permanently exposed to the virus. If you are living an ordinary life in Canada or England or somewhere, you may be equally resistant, but you are also unlikely to be at risk. Here, we can actually witness the immunity in action."

While understandably fascinating for the scientists, the women's extended and continuing exposure has led to charges that they are being exploited. Among those expressing reservations is Dr Ngugi. "If the aim is to fight Aids," she says, "we could start by getting these women out of sex work. You have to ask how this is benefiting them."
Dr Gelmon's response is straightforward. "Frankly, the benefit is that they are alive and well. We give them full, free health care of a kind that they'd never have otherwise. We can't make them give up prostitution. We're not lifestyle counsellors. We can't tell them what to do in their own homes. The reality is that this is how many of them choose to live. Sure, there's a useful element in it for us, but it's a shared benefit."

Which raises the question of where such usefulness is leading? For all the important work that they have done, no one on the Canadian team pretends that an effective vaccine is just around the corner. Five years ago, a team of immunologists from Oxford University produced an experimental vaccine based on the Nairobi research, but the results were disappointing and the project abandoned. "The hope was that we could make a vaccine that would mimic what the women's bodies do naturally," says Prof Andrew McMichael, the university's head of medical research and human immunology. "But there is likely to be a mixture of factors at work, including genetic make-up, and possibly an element of good luck, and it is hard to replicate all these things."

Millions of dollars have been spent in pursuit of Salome's secret; more money than the raggedy inhabitants of Majengo, milling through their foetid alleyways, could ever imagine. Here, Aids is one more affliction, heaped on hardships too many to list. If, in this unlikely human laboratory, lies a miracle cure it will come too late for the thousands already infected. "I hear of people dying every day," says Salome. "Sometimes I feel guilty to be alive. I will be happy if I can help."

And so the search goes on. "My own belief," says Dr Plummer, "is that this research will lead to a vaccine. I don't know when. As someone said, it's difficult to make predictions - especially about the future."