A Paradigm Shift in HIV Therapy: Evaluating CRISPR-Cas9’s Safety and Efficacy in SIV Eradication from Non-Human Primates


The battle against HIV has been a prolonged and arduous one, with significant strides in treatment but no definitive cure. In a groundbreaking study, researchers have shifted the paradigm by using CRISPR-Cas9 gene editing technology to target and excise simian immunodeficiency virus (SIV), a close relative of HIV, from infected non-human primates (NHPs).  CRISPR-Cas9 is a revolutionary gene editing technology that has transformed the field of genetics. It stands for “Clustered Regularly Interspaced Short Palindromic Repeats” and “CRISPR-associated protein 9.” This system, derived from a natural defense mechanism found in bacteria, allows for precise editing of DNA at specific locations in the genome. In a new study published in Gene Therapy by Dr. Jennifer Gordon from the Excision BioTherapeutics, Inc and Professor Kamel Khalili from Temple University investigated a new CRISPR-Cas9 HIV treatment.

The study involved twelve male Indian rhesus macaques, infected with SIV and treated with antiretroviral therapy (ART). They were divided into groups, with varying doses of EBT-001, an AAV9-based vector delivering SaCas9 and dual guide RNAs designed to target the SIV genome. The macaques received a single intravenous infusion of EBT-001. Researchers monitored the animals for weight, lymphocyte and monocyte counts, blood chemistries, cytokine levels, and off-target effects using whole genome sequencing. The biodistribution of the vector DNA in tissues and blood was quantified using a TaqMan-based qPCR assay.

The authors found that EBT-001 was well-tolerated across all dosage groups, with no significant off-target effects or abnormal pathology. This establishes the safety profile of CRISPR-Cas9 in a large animal model, a critical step towards human application. Moreover, the vector DNA was broadly distributed across known tissue reservoirs of SIV, including the spleen, lymph nodes, and colon. This widespread distribution is crucial for targeting the virus in all potential reservoirs. According to the authors, there was successful editing of proviral DNA fragments in blood cells and various organs. The presence of excision products confirmed the effectiveness of CRISPR-Cas9 in excising viral DNA, a promising result for its potential in eradicating HIV. The authors demonstrated that animals treated with EBT-001 showed improvement in absolute lymphocyte counts and maintained normal body weight, suggesting an overall beneficial effect on health. Whole genome sequencing revealed no significant unintended editing events, reinforcing the specificity of CRISPR-Cas9.  Given the similarities between SIV and HIV, these results are a beacon of hope. They demonstrate the potential of CRISPR-based gene editing as a therapeutic approach for HIV in humans.

This research marks a pivotal moment in HIV cure strategies. The use of CRISPR-Cas9 to successfully edit SIV DNA in a large animal model not only demonstrates the feasibility of this approach but also paves the way for human clinical trials. The findings bring us a step closer to a potential cure for HIV, which could transform millions of lives globally. The journey towards an HIV cure has been laden with challenges, but this study illuminates a new path. The safety, efficacy, and precision of CRISPR-Cas9 in excising SIV from non-human primates herald a new era in HIV treatment. While further research is needed, particularly in human trials, the promise shown in this study is undeniably a leap forward in the quest to conquer HIV.

A Paradigm Shift in HIV Therapy: Evaluating CRISPR-Cas9's Safety and Efficacy in SIV Eradication from Non-Human Primates - Medicine Innovates
Image depicting the CRISPR-Cas9 gene editing technology in action. It illustrates the Cas9 enzyme and guide RNA (gRNA) interacting with a DNA strand, set against the detailed backdrop of a cell’s interior. This visualization captures the intricate and precise nature of this groundbreaking technology. Image Credit: Medicine Innovates Graphics Team.

About the author

Jennifer Gordon, Ph.D.

Senior Vice President, R&D
Excision BioTherapeutics, Inc., San Francisco, CA, USA

Jennifer Gordon, Ph.D. is Senior Vice President of Research and Development at Excision BioTherapeutics. Prior to joining Excision, Dr. Gordon spent nearly three decades in academic research, most recently as Associate Professor, Department of Neuroscience and Center for NeuroVirology, and Associate Dean for Research at Temple University School of Medicine.  Dr. Gordon has been the recipient of numerous NIH grants for her research on HIV and JC virus, as well as neurodevelopmental and neurodegenerative disorders. She has published over 125 peer-reviewed research papers, review articles, book chapters, and CME monographs.  She previously served as the Managing Editor of the Journal of NeuroVirology for over 25 years, and served as a long-time Board Member and Officer of the International Society for NeuroVirology.

Dr. Gordon received a B.S. in Biology from Albright College and a Ph.D. in Pathology from MCP-Hahnemann School of Medicine. She completed a postdoctoral fellowship in Molecular Virology in the Department of Biology, College of Science of Technology, Temple University, before joining the faculty at Temple.

About the author

Kamel Khalili, PhD

Laura H. Carnell Professor, Department of Neuroscience
Chair and Professor, Department of Microbiology, Immunology & Inflammation
Director and Professor, Center for Neurovirology & Gene Editing
Director, Comprehensive NeuroAIDS Center
Temple University

The research program in my laboratory consists of three areas associated with neurodegeneration, neuroproliferation and neuroinflammation. In all three areas, the aim is to understand the biological events involved in control of neural cell function, growth and differentiation. To achieve this goal, we use human neurotropic viruses, including JCV and HIV, both of which greatly impact on the normal function of a variety of neural cells, as probes to determine the mechanism involved in the control of gene expression and signal transduction in the brain. As expression and replication of these pathogenic viruses in brain induces a broad range of reversible and irreversible injuries, the outcome of our studies provides fundamental information regarding the neuropathogenesis of HIV- and JCV-induced disorders, and offers excellent opportunities for the development of better diagnostic tests and effective therapeutic modalities. Our strategies are transformative in nature and employ a broad range of molecular and cellular techniques in in vitro studies, animal models and clinical samples. Our most current areas of research lie in understanding the effect of viruses on pathways involved in protein quality control, chromosomal instability upon virus infection of the CNS, pathways involved in neurodegeneration upon HIV infection and the neuroprotective role of glial cells, particularly oligodendrocytes in healthy and disease states, and the identification of cellular factors and signaling events that lead to uncontrolled proliferation of glial cells and the development of malignancies of the brain.


Tricia H. Burdo, Chen Chen, Rafal Kaminski, Ilker K. Sariyer, Pietro Mancuso, Martina Donadoni, Mandy D. Smith, Rahsan Sariyer, Maurizio Caocci, Shuren Liao, Hong Liu, Wenwen Huo, Huaqing Zhao, John Misamore, Mark G. Lewis, Vahan Simonyan, Ethan Y. Xu, Thomas J. Cradick, Jennifer Gordon, Kamel Khalili. Preclinical safety and biodistribution of CRISPR targeting SIV in non-human primates. Gene Therapy, 2023; DOI: 10.1038/s41434-023-00410-4.

Go To Gene Therapy