The Pivotal Role of Combinatorial CRISPR Gene Editing in the Elimination of HIV-1 Infection

Recent research from Temple University’s Lewis Katz School of Medicine and the University of Nebraska Medical Center (UNMC) demonstrates that gene-editing therapy aimed at two targets - HIV-1, the virus that causes AIDS, and CCR5, the co-receptor that aids the virus getting into cells—can effectively eliminate HIV infection.

Image Credit: Temple University

The study, which was published online in the journal The Proceedings of the National Academy of Sciences (PNAS), is the first to use a dual gene-editing technique in conjunction with antiretroviral medications to cure HIV-1 in animals.

“The idea to bring together the excision of HIV-1 DNA with inactivation of CCR5 using gene-editing technology builds on observations from reported cures in human HIV patients. In the few instances of HIV cures in humans, the patients underwent bone marrow transplantation for leukemia, and the donor cells that were used carried inactivating CCR5 mutations,” states Kamel Khalili, PhD, Laura H. Carnell Professor and Chair of the Department of Microbiology, Immunology, and Inflammation, Director of the Center for Neurovirology and Gene Editing, and Director of the Comprehensive NeuroAIDS Center at the Lewis Katz School of Medicine.

The new study’s senior investigators were Dr Khalili and Howard E. Gendelman, MD, Professor and Chair of the Department of Pharmacology and Experiential Neuroscience at UNMC. The two researchers have been working together for a long time and have intentionally combined their scientific strengths to find an HIV cure.

We are true partners, and what we achieved here is really spectacular. Dr Khalili’s team generated the essential gene-editing constructs, and we then applied those constructs in our LASER-ART mouse model at Nebraska, figuring out when to administer gene-editing therapy and carrying out analyses to maximize HIV-1 excision, CCR5 inactivation, and suppression of viral growth.”

Howard E. Gendelman, Professor and Chair, Department of Pharmacology and Experiential Neuroscience, University of Nebraska Medical Center

Drs Khalili and Gendelman and their teams previously demonstrated that HIV can be edited out of the genomes of live, humanized HIV-infected mice, leading to a cure in certain animals.

Dr Khalili and co-investigator Rafal Kaminski, PhD, Assistant Professor at the Katz School of Medicine’s Center for Neurovirology and Gene Editing, merged their expertise in CRISPR gene-editing technology for targeting HIV-1 with a therapeutic strategy identified as long-acting slow-effective release (LASER) antiretroviral therapy (ART) co-developed by Dr Gendelman and Benson Edagwa, PhD, Assistant Professor of Pharmacology at UNMC.

LASER ART reduces the frequency of ART administration by keeping HIV replication at low levels for lengthy periods of time.

Despite successfully eliminating HIV in LASER-ART mice, the researchers discovered that HIV could re-emerge from tissue reservoirs and cause rebound infection. This outcome is analogous to rebound infection in human patients who have been receiving ART but have suddenly stopped or had their therapy interrupted.

Because HIV integrates its DNA into the genome of host cells, it can remain dormant in tissue reservoirs for extended periods of time, beyond the reach of antiretroviral drugs. As a result, when ART is discontinued, HIV replication resumes, giving rise to AIDS.

Dr Khalili and co-workers began work on next-generation CRISPR technology for HIV excision to avoid rebound infection, establishing a new, dual approach targeted at permanently eradicating HIV from the animal model.

“From success stories of human HIV patients who have undergone bone marrow transplantation for leukemia and been cured of HIV, our hypothesis was that the loss of the virus’s receptor, CCR5, is important to permanently eliminating HIV infection,” he details.

Researchers devised a more straightforward and feasible approach for CCR5 inactivation that comprises an IV inoculation of the CRISPR gene editing molecule.

Dr Gendelman’s team demonstrated that when the constructs produced at Temple were provided combined, they resulted in viral suppression, restoration of human T-cells, and elimination of reproducing HIV-1 in 58% of infected animals. The findings support the notion that CCR5 plays an important role in HIV infection.

The Temple team also plans to try the dual gene-editing method in nonhuman primates in the near future. Dr Khalili will work with Tricia H. Burdo, PhD, Professor and Vice Chair in the Department of Microbiology, Immunology, and Inflammation at the Katz School of Medicine, a well-known expert in the use of non-human primate models for studying HIV-1 and a co-author on the new study, to accomplish this.

Dr Burdo and her colleagues are curious about the role of CCR5 in SIV-infected primates. Her lab was previously involved in research that demonstrated the efficacy and safety of CRISPR-based technology in eradicating HIV DNA from primate cells.

The novel dual CRISPR gene-editing technique has great potential for the treatment of HIV in humans. “It is a simple and relatively inexpensive approach. The type of bone marrow transplant that has brought about cures in humans is reserved for patients who also have leukemia. It requires multiple rounds of radiation and is not applicable in resource-limited regions, where HIV infection tends to be most common,” Dr. Khalili noted.

Curing HIV is the big picture. Through our ongoing collaboration, Temple and UNMC have carried out meaningful research that could ultimately impact the lives of many people.”

Howard E. Gendelman, Professor and Chair, Department of Pharmacology and Experiential Neuroscience, University of Nebraska Medical Center