Zurich University Hospital scientists have discovered that the HIV virus survives antiretroviral medicine and can spread from a single infected cell.

Antiretroviral medication suppressed HIV so well that no traces of it appeared in laboratory tests, researchers said. But scientists Beda Joos and Huldrych Guenthard found that the virus that causes Aids resurfaced with astounding rapidity as soon as patients stopped taking the drugs.

That led them to two debateable theories about the virus's ability to survive medical treatment: either it remained in the blood at extremely low levels of infection, or it built itself into a cell's DNA and waited.

The study looked at 20 patients who had been using anti-HIV medication for a long time. Researchers stopped giving the medicines for two-week periods, followed by two-months of steady treatment.

Numerous variations of the virus rapidly resurfaced between treatments. That meant anti-AIDS medication was so effective because it completely paralysed the virus, researchers said.

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