scholarly journals CRISPR-Cas9 Dual-gRNA Attack Causes Mutation, Excision and Inversion of the HIV-1 Proviral DNA

Viruses ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 330 ◽  
Author(s):  
Caroline S. Binda ◽  
Bep Klaver ◽  
Ben Berkhout ◽  
Atze T. Das

Although several studies demonstrated that the HIV proviral DNA can be effectively targeted and inactivated by the CRISPR-Cas9 system, the precise inactivation mechanism has not yet been analyzed. Whereas some studies suggested efficient proviral DNA excision upon dual-gRNA/Cas9 treatment, we previously demonstrated that hypermutation of the target sites correlated with permanent virus inactivation. To better understand the mechanism underlying HIV inactivation, we analyzed the proviral DNA upon Cas9 attack with gRNA pairs. We observed that dual-gRNA targeting resulted more frequently in target site mutation than fragment excision, while fragment inversion was rarely observed. The frequencies varied for different gRNA combinations without an obvious relationship with the distance between the target sites, indicating that other gRNA and target DNA characteristics influence the DNA cleavage and repair processes.

2019 ◽  
Vol 10 ◽  
Author(s):  
Cecilia Sgadari ◽  
Paolo Monini ◽  
Antonella Tripiciano ◽  
Orietta Picconi ◽  
Anna Casabianca ◽  
...  

Author(s):  
M.A. Tyumentseva ◽  
◽  
A.I. Tyumentsev ◽  
V.G. Akimkin ◽  
◽  
...  

For the effective functioning of supervisory and health monitoring services, it is necessary to introduce modern molecular technologies into their practice. Therefore, the task of developing new effective methods for detecting pathogen, for example HIV, based on CRISPR/CAS genome editing systems, remains urgent. In the present work, guide RNAs and specific oligonucleotides were developed for preliminary amplification of highly conserved regions of the HIV-1 genome. The developed guide RNAs make it possible to detect single copies of HIV-1 proviral DNA in vitro as part of CRISPR/CAS ribonucleoprotein complexes in biological samples after preliminary amplification.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bo Zhang ◽  
Diyin Luo ◽  
Yu Li ◽  
Vanja Perčulija ◽  
Jing Chen ◽  
...  

AbstractCas12i is a newly identified member of the functionally diverse type V CRISPR-Cas effectors. Although Cas12i has the potential to serve as genome-editing tool, its structural and functional characteristics need to be investigated in more detail before effective application. Here we report the crystal structures of the Cas12i1 R-loop complexes before and after target DNA cleavage to elucidate the mechanisms underlying target DNA duplex unwinding, R-loop formation and cis cleavage. The structure of the R-loop complex after target DNA cleavage also provides information regarding trans cleavage. Besides, we report a crystal structure of the Cas12i1 binary complex interacting with a pseudo target oligonucleotide, which mimics target interrogation. Upon target DNA duplex binding, the Cas12i1 PAM-interacting cleft undergoes a remarkable open-to-closed adjustment. Notably, a zipper motif in the Helical-I domain facilitates unzipping of the target DNA duplex. Formation of the 19-bp crRNA-target DNA strand heteroduplex in the R-loop complexes triggers a conformational rearrangement and unleashes the DNase activity. This study provides valuable insights for developing Cas12i1 into a reliable genome-editing tool.


2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S183-S183
Author(s):  
Rajesh Gandhi ◽  
Joshua Cyktor ◽  
Ronald Bosch ◽  
Hanna Mar ◽  
Gregory Laird ◽  
...  

Abstract Background HIV-1 proviruses persist in people on antiretroviral therapy (ART) but most are defective and do not constitute a replication-competent reservoir. The decay of infected cells carrying intact compared with defective HIV-1 proviruses has not been well-defined in people on ART. Methods We separately quantified intact and defective proviruses (using an intact proviral DNA assay), residual plasma viremia, and markers of inflammation and activation in people on long-term ART. Longitudinal measurements were done at three timepoints: timepoint 1 was a median of 7.1 years on ART; timepoint 2 was a median of 3.7 years later; timepoint 3 was a median of 5.5 years after timepoint 1 and a median 12 years after starting ART (Figure 1). Figure 1: Study timepoints Results Among 40 participants tested longitudinally from a median of 7.1 years to 12 years after ART initiation, intact provirus levels declined significantly over time (median half-life 7.1 years; 95% confidence interval [CI], 3.9, 18), whereas defective provirus levels did not decrease. The median half-life of total HIV-1 DNA was 41.6 years (95% CI, 13.6, 75). When we evaluated the change in proviral DNA per year, intact proviral DNA declined significantly more (p< 0.001) than defective proviral DNA (the latter did not change) (Figure 2). The proportion of all proviruses that were intact diminished over time on ART, from about 10% at the first on-ART timepoint to about 5% at the last timepoint (Figure 3). At timepoint 1, intact provirus levels on ART correlated with total HIV-1 DNA and residual plasma viremia, but there was no evidence for associations between intact provirus levels and inflammation or immune activation. Figure 2: Percent change in HIV-1 proviral DNA per year Figure 3: Total HIV-1 proviruses (grey bars) and the percentage of intact proviruses (red lines, displaying median, Q1, Q3) by timepoint. Conclusion Cells containing intact, replication-competent proviruses are selectively lost during suppressive ART. Defining the mechanisms involved should inform strategies to accelerate HIV-1 reservoir depletion. Disclosures Rajesh Gandhi, MD, Merck (Advisor or Review Panel member) Gregory Laird, PhD, Accelevir Diagnostics (Shareholder, Other Financial or Material Support, Employee) Albine Martin, PhD, Accelevir Diagnostics (Shareholder, Other Financial or Material Support, Employee) Bernard Macatangay, MD, Gilead (Grant/Research Support) Joseph J. Eron, MD, Gilead Sciences (Consultant, Research Grant or Support)Janssen (Consultant, Research Grant or Support)Merck (Consultant)ViiV Healthcare (Consultant, Research Grant or Support) Janet Siliciano, PhD, Gilead (Advisor or Review Panel member)US Military HIV Research Program (Advisor or Review Panel member) John Mellors, MD, Abound Bio (Shareholder)Accelevir Diagnostics (Consultant)Co-Crystal Pharmaceuticals (Shareholder)Gilead (Consultant, Grant/Research Support)Merck (Consultant)


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