Scientists use stem cells to create HIV resistance

June 10, 2014 by Marcia Malory, Medical Xpress report
hiv
Scanning electron micrograph of an HIV-infected H9 T cell. Credit: NIAID

(Medical Xpress)—Yuet Wai Kan of the University of California, San Francisco and colleagues have created HIV-resistant white blood cells by editing the genomes of induced pluripotent stem cells. The researchers inserted genes with a mutation that confers resistance to HIV into stem cells. White blood cells grown from these stem cells were HIV resistant. The research appears in the Proceedings of the National Academy of Sciences.

The HIV virus attacks CD+4 T cells, a type of white blood cell, by locking onto a protein called CCR5. A small number of people of European descent have a mutation in the gene that codes for CCR5. HIV infection progresses more slowly in people with one copy of this mutation, known as CCR5Δ32, than in people without the mutation. Those who are homozygous for CCR5Δ32 are resistant to HIV infection.

Inserting genes with the CCR5Δ32 mutation into cells of people suffering from HIV infection could cure them of the virus. Previously, scientists tried doing this by transplanting stem cells from people with natural HIV resistance into people with HIV. In a well known case, Timothy Ray Brown, an HIV patient, received stem cells from the bone marrow of someone with the mutation. After the procedure, signs of HIV infection disappeared.

Unfortunately, because so few people naturally carry the CCR5Δ32 mutation, finding enough donors to treat all HIV patients would virtually be impossible. It would be better if scientists could create the mutation in people with the infection. Researchers have tried disrupting normal copies of the gene that codes for CCR5, so the virus could not latch on to the protein. However, this might not be a good idea, as completely destroying the gene could have an unknown harmful effect.

Kan and his team thought a preferable solution would be to recreate the CCR5Δ32 mutation in . People with this mutation usually are healthy, so the team didn't think this would cause any problems. They generated stem cells homozygous for CCR5Δ32, using a new method of genome editing that relies on the CRISPR-Cas9 system, a bacterial immune system that works by splicing DNA from invading viruses into the bacteria's own DNA.

White blood cells derived from the stem cells were HIV resistant. These were not CD+4 T-cells. However, previous attempts to modify the CCR5 gene in CD+4 T cells of HIV-infected patients, using an older genome editing method, show that patients receiving this treatment would require repeated T-cell transplants. The researchers suggest creating HIV resistant , which would later develop into all kinds of blood cells.

Explore further: Scientists uncover features of antibody-producing cells in people infected with HIV

More information: Seamless modification of wild-type induced pluripotent stem cells to the natural CCR5Δ32 mutation confers resistance to HIV infection, Lin Ye, PNAS, DOI: 10.1073/pnas.1407473111

Abstract
Individuals homozygous for the C-C chemokine receptor type 5 gene with 32-bp deletions (CCR5Δ32) are resistant to HIV-1 infection. In this study, we generated induced pluripotent stem cells (iPSCs) homozygous for the naturally occurring CCR5Δ32 mutation through genome editing of wild-type iPSCs using a combination of transcription activator-like effector nucleases (TALENs) or RNA-guided clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 together with the piggyBac technology. Remarkably, TALENs or CRISPR-Cas9–mediated double-strand DNA breaks resulted in up to 100% targeting of the colonies on one allele of which biallelic targeting occurred at an average of 14% with TALENs and 33% with CRISPR. Excision of the piggyBac using transposase seamlessly reproduced exactly the naturally occurring CCR5Δ32 mutation without detectable exogenous sequences. We differentiated these modified iPSCs into monocytes/macrophages and demonstrated their resistance to HIV-1 challenge. We propose that this strategy may provide an approach toward a functional cure of HIV-1 infection.

Related Stories

Scientists uncover features of antibody-producing cells in people infected with HIV

June 3, 2014
By analyzing the blood of almost 100 treated and untreated HIV-infected volunteers, a team of scientists has identified previously unknown characteristics of B cells in the context of HIV infection. B cells are the immune ...

Study identifies population of stem-like cells where HIV persists in spite of treatment

January 12, 2014
Although antiviral therapy against HIV suppresses viral replication and allows infected individuals to live relatively healthy lives for many years, the virus persists in the body, and replication resumes if treatment is ...

HIV can cut and paste in the human genome

May 27, 2014
For the first time researchers have succeeded in altering HIV virus particles so that they can simultaneously, as it were, 'cut and paste' in our genome via biological processes. Developed at the Department of Biomedicine ...

Gene therapy locks out HIV, paving the way to control virus without antiretroviral drug

March 5, 2014
University of Pennsylvania researchers have successfully genetically engineered the immune cells of 12 HIV positive patients to resist infection, and decreased the viral loads of some patients taken off antiretroviral drug ...

NIH study describes new method for tracking T cells in HIV patients

February 3, 2014
A team of researchers has reported a novel method for tracking CD4+ T cells in people infected with HIV. CD4+ T cells are critical for immune defense against an array of pathogens and are a primary target of HIV. In the study, ...

Recommended for you

New simulation tool predicts how well HIV-prophylaxis will work

June 14, 2018
A new mathematical simulation approach predicts the efficacy of pre- and post-exposure prophylaxis (PrEP) medications, which help prevent HIV infection. The framework, presented in PLOS Computational Biology by Sulav Duwal ...

Many at risk for HIV despite lifesaving pill

June 11, 2018
Multiple barriers may stop high-risk individuals from accessing an HIV drug that can reduce the subsequent risk of infection, according to a new University of Michigan study.

Active HIV in large white blood cells may drive cognitive impairment in infected mice

June 7, 2018
Macrophages, large white blood cells that engulf and destroy potential pathogens, harbor active viral reserves that appear to play a key role in impaired learning and memory in mice infected with a rodent version of HIV. ...

HIV vaccine elicits antibodies in animals that neutralize dozens of HIV strains

June 4, 2018
An experimental vaccine regimen based on the structure of a vulnerable site on HIV elicited antibodies in mice, guinea pigs and monkeys that neutralize dozens of HIV strains from around the world. The findings were reported ...

HIV study reveals new group of men at risk of infection

June 4, 2018
A group of men who may be underestimating their HIV risk has been identified in a new study.

Discovery reveals how cells try to control levels of key HIV protein

May 31, 2018
One of the many challenges in treating HIV is that the virus can lie dormant in cells, quietly evading immune detection until it suddenly roars to life without warning and begins replicating furiously. Salk Institute researchers ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Osiris1
not rated yet Jun 13, 2014
Sounds like these folks are flirting with the Nobell Prize. Inasmuch as some have inferred an off world source for this virus and some have even gone so far as to call its cure our 'final exam' as earning our respect and membership in the community of spacefaring sentients, we may by the application of this consider ourselves accepted.

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.