Infected at least 10 years ago by her husband, the woman is able somehow to naturally control the deadly and incurable virus - even though her husband must take cocktails of strong HIV drugs to control his.

She is a so-called "elite suppressor", and studies of her immune cells have begun to offer clues to how her body does it, the team at Johns Hopkins University in Baltimore said.

"This is the best evidence to date that elite suppressors can have fully pathogenic virus," said Dr Joel Blankson, who led the study.

Tests show they are infected with the same strain of virus.

What is different is the immune system of the wife.

"That's a good sign in terms of developing a therapeutic vaccine," Blankson said.

Such a vaccine would not prevent infection but might be used to treat patients.

Both the man and the woman, who are from Baltimore, were diagnosed 10 years ago, Blankson said.

The husband is a former injecting drug user.

Tests showed that immune cells known as CD8 T-cells from the wife stalled HIV replication by as much as 90 per cent, while the husband's T-cells stopped it by only 30 per cent, Blankson's team reported in the Journal of Virology.

Her virus has also mutated in apparent response to this immune attack, becoming weaker, while her husband's virus has remained strong.

Nampa-Reuters

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