Johannesburg - One was a sex worker from Durban. The other lived deep in rural KwaZulu-Natal.
Both were HIV-positive. And both were part of a rare group of people: that one-fifth living with the disease whose bodies produce antibodies that work against a wide range of HIV strains.
Now, by studying their blood samples at different stages in their progression, scientists may be on their way to developing an Aids vaccine.
The Centre for the Aids Programme of Research in SA (Caprisa) consortium brought together scientists from South Africa and the US to examine how and why only some HIV-infected people develop broadly neutralising antibodies – those antibodies that work not just against a single strain of the virus but several different strains.
It’s this changing nature of the virus that has stood in the way of a vaccine in the past, as the antibodies cannot recognise the virus in the body.
So far, the only immunogen that has been able to stimulate these antibodies to develop is HIV itself, and even then only years into the disease.
When a person becomes infected with HIV, their body starts to produce antibodies to fight the virus.
“But the virus gets there first,” said lead author and virologist Dr Penny Moore, of the National Institute of Communicable Diseases. “It’s always changing, always just one step ahead.”
Now, the scientists have discovered that as the virus changes with time, so do the antibodies.
“They try to paint the virus into a corner, to get it to expose a vulnerability that will help them identify it,” explained Moore.
As the disease reaches an advanced stage, the virus coats itself with a sugar – glycan – to protect itself against the constant onslaught of antibodies. And it’s this sugar that is the key.
Broadly neutralising antibodies can recognise it, target it and bind themselves to it. The result: the virus is blocked from infecting healthy cells in the body.
It’s not a cure, emphasised Caprisa director Professor Salim Abdool Karim.
But understanding how these antibodies evolve may be the next step towards developing a vaccine.
The fact that the antibodies develop only at an advanced stage of the disease means they did not help the two women whose blood made the discovery possible.
One continues to live a happy life, now on antiretroviral treatment, but she will never be cured. The other succumbed to extreme drug-resistant TB.
Karim paid tribute to them and the thousands of other people living with HIV: “There was little benefit in it for themselves, but it may have a great benefit to the world.” - The Star