Search for Aids cure shifts to prostitutes with immunity

• Women from Nairobi slum have antibodies capable of stopping virus before it attacks

A few years later, another vaccine based on the same cellular immune response concept was tried in South Africa in what has come to be popularly known as the STEP Trial. This too failed.

Then came the Merck vaccine, which failed after entering the most advanced stage of the clinical trials.

But as these trials aborted, the active prostitutes in Majengo and other parts of Nairobi had little to worry about as they continued to resist the virus, confounding the scientists even further.

“We went back to basic science to understand why these women continued to have an excellent immune system,” says Dr Joshua Kimani, the clinical director of research for University of Nairobi and University of Manitoba.

Despite the drawbacks they have faced over the years, the researchers did not give up on the Majengo women.

Now, millions of shillings are being spent on fresh research to follow the Majengo prostitutes to establish their intriguing ability to defy HIV.

Scientists have renewed the efforts to understand why these women are a special breed. Many of the researchers, including Dr Kimani, still believe the solution to getting an effective vaccine lies with these women.

This quest for answers has seen researchers from University of Nairobi and University of Manitoba open up new centres in Korogocho and Kangemi to study more prostitutes there. The research will go on until 2010 and is expected to shed more light on resistance to HIV infection.

The women being recruited now are HIV negative prostitutes, who will then be studied for a period of three years to monitor their responses to HIV or any other sexually transmitted disease. So far, five per cent of them have been found to have the ability to resist HIV.

In recent times, some of the prostitutes have also been found to produce neutralising antibodies that stop HIV from infecting their cells. Unlike the killer T-cells, which kill an infected cell, the neutralising antibodies stop HIV from infecting the cell in first place.

Focus is now being put on finding neutralising antibodies in HIV positive individuals and then use them to develop an effective Aids vaccine. And the scientists appear to be succeeding on this front.

“What we are experiencing now is phenomenal and provides critical information of how we move forward and the massive work we need to undertake in this direction,” says Dr Wayne Koff of International Aids Vaccine Initiative.

In an interview with the Daily Nation, Dr Koff said his group had identified four antibodies that could neutralise the virus.
Immune systems

In this quest, the researchers are also paying attention to immune systems of individuals who have lived with HIV for the past three years without using anti-retroviral medicine. Some of them are believed to possess the neutralising antibodies.

Also to be studied are discordant couples — where one partner is HIV negative and the other positive.