Real or Not? HIV Cure in Animals Using CRISPR Gene Editing
May 4, 2017
You may have heard about the story that's been making the media rounds regarding a potential HIV cure using gene editing that had been tested in animals. (If you haven't, you can see examples from CBS News, Daily Mail, HuffPost UK, The Independent, Science Daily, The Sun, and TechCrunch.) Here's some help making sense of the story, including what's true or not, and what to get excited about.
Researchers at Temple University and the University of Pittsburgh have been able to cut HIV out of infected cells in mice. They do this through a gene-editing method known as CRISPR/Cas9, or simply CRISPR for short, according to a new study published in Molecular Therapy.
Here's a video explaining how CRISPR can cut the HIV DNA out an infected cell:
In this new study, the researchers used CRISPR in transgenic mice and reduced HIV RNA expression (a measure of HIV presence and activity) by about 60-95% -- which confirmed the findings from the first mouse study from last year. They then tested the method in mice with EcoHIV, a mouse equivalent of HIV, during acute infection (very soon after infection) and found 96% effectiveness.
They also tested the method in humanized mice (mice modified to have human immune cells). In that final test, they found that CRISPR was able to remove HIV from latently infected cells. In humans, latently infected cells are the last hiding place for HIV where current antiretroviral therapy cannot reach.
What's Not Entirely Accurate
Some of the news stories out there, including this article from The Daily Mail, state that the researchers "completely eliminated" HIV from animals and that it was the "first time ever." That's not entirely accurate.
The new study shows a drastic reduction in HIV, but not complete eradication. And, it isn't the first time we've seen a cure-like response in animal studies. It's not even the first time we've seen it with CRISPR, since the same research team published proof-of-concept results last year. Moreover, in 2013 we saw a vaccine clearing the monkey version of HIV in macaques (SIV), and in a study last year, researchers announced sustained remission of SIV in monkeys given an experimental antibody.
Possible Reasons to Get Excited
"These are indeed significant results from a reputable research group that has previously presented work on CRISPR/cas9 and HIV, demonstrating that the targeted genetic therapy can excise integrated HIV genomes from mice," Benjamin Young, M.D., Ph.D., senior vice president and chief medical officer of the International Association of Physicians in AIDS Care (IAPAC), told TheBody.com.
"These results should be very exciting to the HIV cure field, but the community should be careful to appreciate that these are still non-human studies in an early phase of development. It is not yet a cure for HIV in people," Young added.
"There will need to be very extensive future studies on genome toxicity (genetic injury) and other safety aspects of CRISPR before moving into large human trials. These are important examples of the concept that investment in basic science often yields novel concepts from unexpected places. Who would have thought that study of bacterial defense systems (it's what CRISPR does in its natural environment) would yield the most exciting genetic therapeutic strategy in decades?" Young concluded.
What's Next for CRISPR and HIV?
"The next stage would be to repeat the study in primates, a more suitable animal model where HIV infection induces disease, in order to further demonstrate elimination of HIV-1 DNA in latently infected T cells and other sanctuary sites for HIV-1, including brain cells. Our eventual goal is a clinical trial in human patients," said study author Kamel Khalili, Ph.D., according to the study press release.
While CRISPR is very promising, we're still a long way from seeing it tested in humans, let alone from calling it a "cure." We have also already seen HIV fight back. Last year, a study found that HIV quickly mutates and overcomes CRISPR within two weeks.
Warren Tong is the senior science editor for TheBody.com and TheBodyPRO.com.
Follow Warren on Twitter: @WarrenAtTheBody.
This article was provided by TheBody.com.
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