How can we use Gene Editing to protect or cure us from viral infections?
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Is the problem still unsolved?
Is it concisely described?
- What are the risks of eliminating our natural cell receptors to avoid viral infections through them?
- What gene editing designs would be more efficient and safer to target latent infections? Would knock-out be enough or should we aim for targeted deletion of viral sequences?
- What are the best ways to deliver the treatment to the infected area? (topic, systemic?)
- How can we make sure that we have edited all cells containing the virus?
- How can we be sure that this approach is safe? How can we avoid generation of Cas9-resistant viruses and of chromosomal rearrangements?
- How can we quantify the benefit generated? Is it enough to justify the risks? Should we limit it to life-threatening conditions?
- Would it be ethical to use gene editing to make us immune to other viruses apart from HIV? Should we wait until infections occur before treating? Is it worth the risks doing it directly in tissues, or should we limit it to ex-vivo approaches?
- Could we potentially adapt the bacterial immune system to be active in all cells of our organism, generating superhumans with resistance to a library of viruses?
Ernst, M.P.T., et al., Ready for Repair? Gene Editing Enters the Clinic for the Treatment of Human Disease. Mol Ther Methods Clin Dev, 2020. 18: p. 532-557.
Lee, C., CRISPR/Cas9-Based Antiviral Strategy: Current Status and the Potential Challenge. Molecules, 2019. 24(7).
Using Recombinase to achieve targeted HIV excision
- CCR5 is not the only entry point of the virus
- Transcriptionally silent ( and still able to replicate) virus reservoir can still be present in the organism, for example in resting memory CD4+ T cells . This may result in the rebound of the virus for example at the moment in which it becomes able to infect via the CXCR4 receptor .
- can eradicate the virus, instead of preventing its entry
- no off-targets were detected due to the high specificity of the engineering of the protein
- it doesn’t trigger a DNA repair response which in some papers has been linked to p53 pathway activation and toxic responses like apoptosis
- to date, no “anti-recombinase” immune response ( like for CRISPR) has been reported
Falkenhagen A, Joshi S. Genetic Strategies for HIV Treatment and Prevention. Mol Ther Nucleic Acids. 2018;13:514-533. doi:10.1016/j.omtn.2018.09.018
Alkhatib G. The biology of CCR5 and CXCR4. Curr Opin HIV AIDS. 2009;4(2):96-103. doi:10.1097/COH.0b013e328324bbec
Battistini, A. & Sgarbanti, M. HIV-1 latency: an update of molecular mechanisms and therapeutic strategies. Viruses 6, 1715–1758 (2014).
Verheyen J, Thielen A, Lübke N, Dirks M, Widera M, Dittmer U, Kordelas L, Däumer M, de Jong DCM, Wensing AMJ, Kaiser R, Nijhuis M, Esser S. Rapid Rebound of a Preexisting CXCR4-tropic Human Immunodeficiency Virus Variant After Allogeneic Transplantation With CCR5 Δ32 Homozygous Stem Cells. Clin Infect Dis. 2019 Feb 1;68(4):684-687. doi: 10.1093/cid/ciy565. PMID: 30020413.
Yu S, Yao Y, Xiao H, Li J, Liu Q, Yang Y, Adah D, Lu J, Zhao S, Qin L, Chen X. Simultaneous Knockout of CXCR4 and CCR5 Genes in CD4+ T Cells via CRISPR/Cas9 Confers Resistance to Both X4- and R5-Tropic Human Immunodeficiency Virus Type 1 Infection. Hum Gene Ther. 2018 Jan;29(1):51-67. doi: 10.1089/hum.2017.032. Epub 2017 Jun 9. PMID: 28599597.
Lekomtsev, S., Aligianni, S., Lapao, A. et al. Efficient generation and reversion of chromosomal translocations using CRISPR/Cas technology. BMC Genomics 17, 739 (2016). https://doi.org/10.1186/s12864-016-3084-5
Karpinski, J., Hauber, I., Chemnitz, J. et al. Directed evolution of a recombinase that excises the provirus of most HIV-1 primary isolates with high specificity. Nat Biotechnol 34, 401–409 (2016). https://doi.org/10.1038/nbt.3467
Crudele, J.M., Chamberlain, J.S. Cas9 immunity creates challenges for CRISPR gene editing therapies. Nat Commun 9, 3497 (2018). https://doi.org/10.1038/s41467-018-05843-9
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Multiplex targeting of highly conserved regions to minimize mutational escape