What′s changed since the last HIV meeting? | Science| In-depth reporting on science and technology | DW | 20.07.2017
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World AIDS Conference IAS2017

What's changed since the last HIV meeting?

As the world's top HIV experts head to Paris for an International AIDS Society meeting, word is we're still playing catch-up with the virus. And if resistance to antiretroviral drugs grows, things will only get worse.

There is always a subtle change here or there. But years can go by in the field of HIV and AIDS, from one official report to another, and from one initiative to another, and sadly, very little really changes. Almost 35 years after the virus was discovered by Françoise Barré-Sinoussi and Luc Montaigner, we're still talking about a global epidemic. And we're still only "playing catch up."

Now, as world HIV experts prepare to talk through the latest science in Paris at IAS 2017, a biannual meeting of the International AIDS Society, new statistics suggest those experts will have to fight the battle on an emerging front: HIV drug resistance.

The World Health Organization has a new report out suggesting 6 out of 11 countries surveyed in Africa, Asia and Latin America show significant drug resistance levels. In those countries "over 10 percent of people starting antiretroviral therapy had a strain of HIV that was resistant to some of the most widely used HIV medicines."

What this will do for the UNAIDS 90-90-90 initiative is anyone's guess. The initiative wants to see 90 percent of people with a diagnosed HIV infection on antiretroviral therapy, and it wants to achieve viral suppression among 90 percent of those people.

But what if the drugs no longer work?

"If resistance is 10 percent in some countries, I find that concerning, because it means a resistant virus has already been transmitted, and that's a high rate," says Professor Hendrik Streeck, who heads Germany's first dedicated HIV research lab in Essen.

With five different classes of HIV drugs the threat of resistance may not yet be a global one. But the WHO predicts an additional 135,000 deaths and 105,000 new infections in the next five years if we fail to act.

"That depends on how often a resistant virus is transmitted. If a person takes antiretroviral drugs the wrong way and they develop a resistance, the mutation of the virus can take over, and if that person transmits that mutation to another person, that other person can't be treated with the same drug," says Streeck. "And usually it's a whole class of drugs. So with rates of 10 percent, we could be on the brink of losing whole classes of drugs."

Suppression is a temporary fix

When antiretroviral treatment came on the scene, it changed a lot. In fact, it saved people's lives. But the drugs are never more than a temporary fix, even when they work.

Antiretroviral drugs will reduce the virus to undetectable levels. But it's still there. So if you stop treatment - either voluntarily or because you can't access the drugs - the virus will break out again.

"HIV is very smart. It can hide away in the body, and that's what we call latency," says Dr Wenhui Hu, an associate professor at Temple University's Lewis Katz School of Medicine. "So we're trying to remove the latent HIV completely for a permanent cure."

Wenhui Hu Professor am Center for Metabolic Disease Research (Danielle Hu)

Still no HIV cure? Wenhui Hu and his team are working on a gene editor that will excise latent HIV cells for good

In some cases the virus will integrate itself into a patient's own genome. The viral DNA, or HIV proviral DNA, "can become your own DNA," says Hu.

He and his team are researching two methods, one of which involves the gene editing technology, CRISPR/Cas9. Another technique, known as Shock and Kill, reactivates the latent cells, and using latency-reversing drugs, kills the cell. But there can be side-effects. Gene editing, meanwhile, is less indiscriminate.

"So we use gene editing technology to target a specific latent cell. With CRISPR/Cas9 we can target only the HIV positive cells. Our 'dCas9' technology induces more power to shock the latent virus and deliver a direct suicide, and you don't have to depend on your immune system," says Hu.

Cures versus vaccines

A cure for HIV sounds as good as a cure for cancer. But there's still no real cure for either. Besides, experts like Mitchell Warren, who heads the advocacy group AVAC, say prevention is better than cure.

"To be successful, even within the 90-90-90 model, includes scaling up prevention through circumcision, condom use, oral PrEP (pre-exposure prophylaxis)," says Mitchell. "And we have to make sure there's simultaneous investment in the innovation and new technology, like gene editing and vaccine or HIV remission and cure research. Going into Paris, that's a very complex balance to strike."

The complexity and truth, says Warren, is that 90-90-90 and treatment alone won't end the epidemic if we don't stop new infections at the same time. Warren says we're not getting ahead of the epidemic, "we're still playing catch up."

"We're beginning to see progress toward those 90-90-90 numbers - getting people on treatment and seeing viral suppression go up, but we're not seeing the overall impact on the epidemic in nearly as rapid a frame. We aren't seeing the rapid reduction in new infections," says Warren.

For that we may need a vaccine far more than a cure - if we can't have the full arsenal.

"A cure for HIV will help the individuals who are treated, but it will not help on the epidemic scale," says Streeck. "Especially with sexually transmitted diseases, where people tend not to get monitored enough, they're stigmatized or ashamed to talk about it. And so a cure might slow the epidemic down, but it won't stop it."

The 9th IAS Conference on HIV Science (IAS 2017) runs from July 23-26, 2017, in Paris. 

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