Scientists eliminate HIV-1 from genome of human T-Cells

March 21, 2016
HIV-1 Virus. Credit: J Roberto Trujillo/Wikipedia

A specialized gene editing system designed by scientists at the Lewis Katz School of Medicine at Temple University is paving the way to an eventual cure for patients infected with HIV, the virus that causes AIDS. In a study published online this month in the Nature journal, Scientific Reports, the researchers show that they can both effectively and safely eliminate the virus from the DNA of human cells grown in culture.

According to senior investigator on the new study, Kamel Khalili, PhD, Laura H. Carnell Professor and Chair of the Department of Neuroscience, Director of the Center for Neurovirology, and Director of the Comprehensive NeuroAIDS Center at the Lewis Katz School of Medicine at Temple University (LKSOM), "Antiretroviral drugs are very good at controlling HIV infection. But patients on antiretroviral therapy who stop taking the drugs suffer a rapid rebound in HIV replication." The presence of numerous copies of HIV weakens the immune system and eventually causes acquired immune deficiency syndrome, or AIDS.

Curing HIV/AIDS—which has claimed the lives of more than 25 million people since it was first discovered in the 1980s - is the ultimate goal in HIV research. But eliminating the virus after it has become integrated into CD4+ T-cells, the cells primarily infected with HIV, has proven difficult. Recent attempts have focused on intentionally reactivating HIV, aiming to stimulate a robust immune response capable of eradicating the virus from . However, to date, none of these "shock and kill" approaches has been successful.

Dr. Khalili and colleagues decided to try a different approach, specifically targeting HIV-1 proviral DNA (the integrated viral genome) using uniquely tailored technology. Their system includes a guide RNA that specifically locates HIV-1 DNA in the T-cell genome, and a nuclease enzyme, which cuts the strands of T-cell DNA. Once the nuclease has edited out the HIV-1 DNA sequence, the loose ends of the genome are reunited by the cell's own DNA repair machinery.

In previous work, Dr. Khalili's team had demonstrated the ability of their technology to snip out HIV-1 DNA from human cell lines. In their latest study, however, they concentrated on latently and productively infected CD4+ T cells to show not only that the technology eliminates the virus from cells but also that its persistent presence in HIV-1-eradicated cells actually protects them against reinfection. More importantly, they carried their work over to ex vivo experiments, in which T-cells from patients infected with HIV were grown in cell culture, showing that treatment with the gene editing system can suppress viral replication and dramatically reduce viral load in patient cells.

In another major component of the study, Dr. Khalili's team addressed questions about off-target effects and toxicity. Using an approach known as ultra-deep whole-genome sequencing, which is considered the gold standard for genomic assessment, the researchers analyzed the genomes of HIV-1-eradicated cells for mutations in genes outside the region targeted by the guide RNA. Their analyses ruled out off-target effects on genes, including potential collateral effects on cellular gene expression. Studies of cell viability and proliferation showed that HIV-1-eradicated cells were growing and functioning normally.

"The findings are important on multiple levels," Dr. Khalili said. "They demonstrate the effectiveness of our gene editing system in eliminating HIV from the DNA of CD4 T-cells and, by introducing mutations into the viral genome, permanently inactivating its replication. Further, they show that the system can protect cells from reinfection and that the technology is safe for the , with no toxic effects."

"These experiments had not been performed previously to this extent," he added. "But the questions they address are critical, and the results allow us to move ahead with this technology."

Explore further: High viral load in HIV-infected individuals underlies innate immune cell dysfunction

More information: Rafal Kaminski et al. Elimination of HIV-1 Genomes from Human T-lymphoid Cells by CRISPR/Cas9 Gene Editing, Scientific Reports (2016). DOI: 10.1038/srep22555

Related Stories

High viral load in HIV-infected individuals underlies innate immune cell dysfunction

March 17, 2016
Individuals infected with HIV exhibit both severe immune deficiency and aberrant inflammation, resulting in susceptibility to secondary infection as the disease progresses. HIV-associated deficiencies in adaptive immune responses ...

Scientists eliminate the HIV virus from cultured human cells for first time

July 21, 2014
The HIV-1 virus has proved to be tenacious, inserting its genome permanently into its victims' DNA, forcing patients to take a lifelong drug regimen to control the virus and prevent a fresh attack. Now, a team of Temple University ...

Researchers prove HIV targets tissue macrophages

March 8, 2016
Investigators in the Division of Infectious Diseases at the University of North Carolina School of Medicine have clearly demonstrated that HIV infects and reproduces in macrophages, large white blood cells found in the liver, ...

Antibodies from unconventional B cells less likely to neutralize HIV, study finds

March 17, 2016
Antibodies derived from a type of immune cell found in unusually high numbers in HIV-infected individuals with chronically uncontrolled virus levels are less effective at neutralizing HIV than antibodies derived from a different ...

Researchers find tough new obstacle to HIV cure strategies

February 15, 2016
(Medical Xpress)—It's a good news/bad news scenario: Researchers have made a new discovery about HIV that will redirect curative strategies toward latent reservoirs of HIV—that's the good news. The bad news is that they ...

Recommended for you

Scientists divulge latest in HIV prevention

July 25, 2017
A far cry from the 1990s "ABC" campaign promoting abstinence and monogamy as HIV protection, scientists reported on new approaches Tuesday allowing people to have all the safe sex they want.

Girl's HIV infection seems under control without AIDS drugs

July 24, 2017
A South African girl born with the AIDS virus has kept her infection suppressed for more than eight years after stopping anti-HIV medicines—more evidence that early treatment can occasionally cause a long remission that, ...

Meds by monthly injection might revolutionize HIV care (Update)

July 24, 2017
Getting a shot of medication to control HIV every month or two instead of having to take pills every day could transform the way the virus is kept at bay.

Candidate AIDS vaccine passes early test

July 24, 2017
The three-decade-old quest for an AIDS vaccine received a shot of hope Monday when developers announced that a prototype triggered the immune system in an early phase of human trials.

Paris spotlight on latest in AIDS science

July 21, 2017
Some 6,000 HIV experts gather in Paris from Sunday to report advances in AIDS science as fading hopes of finding a cure push research into new fields.

Scientists elicit broadly neutralizing antibodies to HIV in calves

July 20, 2017
Scientists supported by the National Institutes of Health have achieved a significant step forward, eliciting broadly neutralizing antibodies (bNAbs) to HIV by immunizing calves. The findings offer insights for HIV vaccine ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.