Important note: Information in this article was accurate in 2004. The state of the art may have changed since the publication date.
Sunday Times (Johannesburg) - December 12, 2004
Brett Horner
"Those of us with 'fitter genes' for protection against HIV are more likely to fight off an attack"
SOUTH African scientists have discovered that the ability of an HIV-infected person to fight the disease is determined by the genes they inherit from their ancestors.
In a study written up this week in the prestigious journal Nature, Durban medical scientists, in conjunction with counterparts from the universities of Oxford and Harvard, identify a particular gene that plays a leading role in the body's defence against HIV.
The team found this gene was passed on to future generations and played a role in the evolutionary development of the human immune system.
The study has also raised hope of finding a vaccine to combat the virus.
Samples for the study were taken from 375 pregnant women in Durban and the research was carried out over three years.
What also emerged was an evolutionary "war" taking place between the virus and the human immune system. The scientists found that although the virus was constantly mutating, human immune-response genes adapted their defence mechanisms to counter the changes.
Professor Jerry Coovadia, a University of KwaZulu-Natal HIV/Aids expert who was a leading member of the research team, said a key outcome of the study was how ancestry had played a fundamental role in determining how the immune system of an infected individual dealt with the virus.
"The main findings of this study show that not only is the virus changing rapidly as it mutates to escape from our protective immune responses, but those of us with 'fitter genes' for protection against the virus are more likely to fight off the attack."
The team found that certain types of a gene called HLA-B are more protective and therefore determine how well the virus can be controlled and how long a person will survive with the disease.
HLA-B genes tell the immune system which cells in the body the virus has infected and so must be destroyed.
It is these "fitter" genes that are passed on to future generations.
Coovadia said this amounted to "an evolutionary process" that had been going on for thousands of years, during which our ancestors were exposed to innumerable diseases.
A fellow author of the study, Dr Photini Kiepiela, said it meant that, in time, the fitter would survive.
"What you will find is that people with [weaker genes] will not actually be around because they won't be passed on to the next generation."
She added that the results would help in the quest for a vaccine specific to the target population.
"You have to be careful what you put into a vaccine. It has to be tailor-made," Kiepiela said.
Bruce Walker, co-author of the study and managing director of the Aids programme at the Massachusetts General Hospital, praised the study as a step in the right direction.
"The Aids crisis will only be solved with the development of an effective vaccine," he said.
"This study's results help to tell us what the most effective immune responses are."
US doctor Philip Goulder, a principal investigator with the research team, agreed with Walker's views.
"The findings will help in understanding precisely how the immune system can succeed or fail against HIV, a prerequisite for a rational approach towards design of an HIV vaccine," Goulder said.
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