Why is HIV incurable?

Hope for a cureMedicines made HIV-infected people virus-free

So far: an HIV infection is treatable - but not curable. The only exceptions to this rule were the so-called "Berlin patient" and the "London patient". In both cases, the cure for HIV was a side effect of successful cancer treatment. The patients had received a stem cell transplant - with cells that are insensitive to the HIV virus.

However, at the 23rd World AIDS Conference, which took place virtually because of the corona pandemic and is ending today, an HIV patient from Sao Paulo, Brazil, was presented whose case attracted a great deal of attention. Since discontinuing intensive drug therapy over a year ago, no HIV viruses have been detectable in the man's blood. This raises hopes that AIDS could in future be curable with medication alone. But it is too early to celebrate a breakthrough in AIDS therapy.

Is the Sao Paolo patient the third HIV patient cured?

No. The man has not needed AIDS medication for over a year, viruses are no longer detectable in his body and there are no longer any antibodies against HIV in his blood. Even so, caution should be exercised: a relapse could still occur. A single virus left in the body can be enough to cause the infection to flare up again.

This was shown by the case of the Mississippi Baby a few years ago. That too seemed cured at first. But after two years there was a relapse. Today the child has to take HIV medication again to keep the virus in check. Against this background, the successful therapy of the Sao Paolo patient is an astonishing stage victory. Whether he is really healed remains to be seen.

With which therapy was this stage success achieved?

The man was 34 when he tested positive for HIV in October 2012. He then received a completely normal combination therapy with three active ingredients for four years. In 2016, this therapy was then significantly intensified. He was given two additional AIDS drugs. First: Dolutegravir - an active ingredient that prevents the AIDS virus from incorporating its genetic material into cells. Second, maraviroc - a substance that prevents the virus from entering immune cells. In addition, the patient received high-dose vitamin B3. This substance, which can be bought without a prescription in drugstores and pharmacies, is sometimes used as an accompaniment to HIV therapy so that the immune system can recover better. The researchers headed by Ricardo Diaz from Sao Paulo speculate that the substance may also have previously overlooked effects. It could be that it activates dormant immune cells infected with HIV, making the viruses vulnerable to the drugs. Dormant viruses hidden in the body have so far been the biggest obstacle on the way to a cure for HIV. Should the Sao Paulo patient prove to be cured in the long term, then the additional vitamin B3 given has probably contributed to this.

Should all HIV patients be consuming vitamin B3 now?

No, because the exact mechanisms of action are still completely unclear. At the moment there is only one hint: the material might be helpful. Whether it really is must be scientifically proven in large studies. With regard to the chances of success, caution is advised: the researchers treated a total of five patients with the intensified drug therapy. But only one of them, the Sao Paulo patient, has achieved temporary success. Nevertheless, the case nourishes the hope that it might be possible to cure AIDS only with medication - that is, without an expensive and dangerous stem cell transplant.

What other approaches are being tried to cure HIV with drugs?

One approach is to gradually make a patient's immune system insensitive to HI viruses so that it can control the pathogens on its own - and possibly even remove them from the body. The disadvantage: This is a very complex and very expensive approach, which has not yet been proven to work.

Another approach is to wake up dormant, infected cells in a targeted manner and to activate the AIDS viruses hidden in them. They would then be vulnerable to drugs or special defense molecules, so-called neutralizing antibodies. The ideal 'alarm clock' for these cells has not yet been found. The Sao Paulo patient may provide new impulses here.