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Published : Tuesday, June 12, 2012 00:00 Article Views : 151 Written by : AFP

PARIS: Scientists said that they had found a key clue on why a tiny minority of individuals infected with HIV (human immunodeficiency virus) has a natural ability to fight off AIDS (Acquired Immune Deficiency Syndrome).

In a study they said holds promise for an HIV vaccine, researchers from four countries reported that the secret lies not in the number of infection-killing cells a person has, but in how well they work.

According to previous research, only about one person in 300 has the ability to control the human immunodeficiency virus (HIV) without drugs, using a strain of killer cells called cytotoxic T lymphocyte (CTL) cells.

Taking that discovery further, scientists from the United States, Canada, Japan and Germany reported that the strain has molecules called receptors that are better able to identify HIV-infected white blood cells for attack.

Until now, it was well-known that people with HIV have tons of these killer cells, Bruce Walker, an infectious diseases expert at the Ragon Institute in Massachusetts, told Agence France-Presse.

We have been scratching our heads since then, asking how, with so many killer cells around, people are getting AIDS. It turns out there is a special quality that makes them [some cells] better at killing, he said.

The study looked at 10 infected people, of whom five took antiretroviral drugs to keep HIV under control while the rest were so-called elite controllers who remained naturally healthy.

HIV kills a type of white blood cell called CD4, leaving people with AIDS wide open to other, opportunistic and potentially deadly infections.

What we found was that the way the killer cells are able to see infected cells and engage them was different, Walker said.

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Secret of HIV killer cells revealed