scholarly journals Efficient CRISPR editing with a hypercompact Cas12f1 and engineered guide RNAs delivered by adeno-associated virus

2021 ◽  
Author(s):  
Do Yon Kim ◽  
Jeong Mi Lee ◽  
Su Bin Moon ◽  
Hyun Jung Chin ◽  
Seyeon Park ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Eukaryotic Cells ◽  
Adeno Associated Virus ◽  
Guide Rna ◽  
Guide Rnas ◽  
Cleavage Activity ◽  
Large Deletions ◽  
Complementary Region ◽  
Low Activity ◽  
Indel Frequency

AbstractGene therapy would benefit from a miniature CRISPR system that fits into the small adeno-associated virus (AAV) genome and has high cleavage activity and specificity in eukaryotic cells. One of the most compact CRISPR-associated nucleases yet discovered is the archaeal Un1Cas12f1. However, Un1Cas12f1 and its variants have very low activity in eukaryotic cells. In the present study, we redesigned the natural guide RNA of Un1Cas12f1 at five sites: the 5′ terminus of the trans-activating CRISPR RNA (tracrRNA), the tracrRNA–crRNA complementary region, a penta(uridinylate) sequence, the 3′ terminus of the crRNA and a disordered stem 2 region in the tracrRNA. These optimizations synergistically increased the average indel frequency by 867-fold. The optimized Un1Cas12f1 system enabled efficient, specific genome editing in human cells when delivered by plasmid vectors, PCR amplicons and AAV. As Un1Cas12f1 cleaves outside the protospacer, it can be used to create large deletions efficiently. The engineered Un1Cas12f1 system showed efficiency comparable to that of SpCas9 and specificity similar to that of AsCas12a.

scholarly journals Unified energetics analysis unravels SpCas9 cleavage activity for optimal gRNA design

2019 ◽  
Vol 116 (18) ◽  
pp. 8693-8698 ◽  
Author(s):  
Dong Zhang ◽  
Travis Hurst ◽  
Dongsheng Duan ◽  
Shi-Jie Chen
Keyword(s):  
Genome Engineering ◽  
Learning Approaches ◽  
Loop Formation ◽  
Unified Framework ◽  
Guide Rna ◽  
Guide Rnas ◽  
Cleavage Activity ◽  
Protospacer Adjacent Motif ◽  
Traditional Approaches ◽  
Target Effects

While CRISPR/Cas9 is a powerful tool in genome engineering, the on-target activity and off-target effects of the system widely vary because of the differences in guide RNA (gRNA) sequences and genomic environments. Traditional approaches rely on separate models and parameters to treat on- and off-target cleavage activities. Here, we demonstrate that a free-energy scheme dominates the Cas9 editing efficacy and delineate a method that simultaneously considers on-target activities and off-target effects. While data-driven machine-learning approaches learn rules to model particular datasets, they may not be as transferrable to new systems or capable of producing new mechanistic insights as principled physical approaches. By integrating the energetics of R-loop formation under Cas9 binding, the effect of the protospacer adjacent motif sequence, and the folding stability of the whole single guide RNA, we devised a unified, physical model that can apply to any cleavage-activity dataset. This unified framework improves predictions for both on-target activities and off-target efficiencies of spCas9 and may be readily transferred to other systems with different guide RNAs or Cas9 ortholog proteins.

ASSESSMENT OF EFFICIENCY AND OFF-TARGET ACTIVITY OF CRISPR/CAS RIBONUCLEOPROTEIN COMPLEXES

2020 ◽  
Author(s):  
Y.V. Mikhaylova ◽  
◽  
M.A. Tyumentseva ◽  
A.A. Shelenkov ◽  
Y.G. Yanushevich ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Correct Choice ◽  
Target Sequence ◽  
Dna Breaks ◽  
Gene Encoding ◽  
Guide Rna ◽  
Guide Rnas ◽  
Ribonucleoprotein Complexes ◽  
Chemokine Receptor Ccr5 ◽  
Target Activity

In this study, we assessed the efficiency and off-target activity of the CRISPR/CAS complex with one of the selected guide RNAs using the CIRCLE-seq technology. The gene encoding the human chemokine receptor CCR5 was used as a target sequence for genome editing. The results of this experiment indicate the correct choice of the guide RNA and efficient work of the CRISPR- CAS ribonucleoprotein complex used. CIRCLE-seq technology has shown high sensitivity compared to bioinformatic methods for predicting off-target activity of CRISPR/CAS complexes. We plan to evaluate the efficiency and off-target activity of CRISPR/CAS ribonucleoprotein complexes with other guide RNAs by slightly adjusting the CIRCLE-seq-technology protocol in order to reduce nonspecific DNA breaks and increase the number of reliable reads.

Basic Biology of Adeno-Associated Virus (AAV) Vectors Used in Gene Therapy

2014 ◽  
Vol 14 (2) ◽  
pp. 86-100 ◽  
Author(s):  
Balaji Balakrishnan ◽  
Giridhara Jayandharan
Keyword(s):  
Gene Therapy ◽  
Adeno Associated Virus ◽  
Basic Biology

Comparative Study of Adeno-associated Virus, Adenovirus, Bacu lovirus and Lentivirus Vectors for Gene Therapy of the Eyes

2017 ◽  
Vol 17 (3) ◽  
Author(s):  
Giedrius Kalesnykas ◽  
Emmi Kokki ◽  
Laura Alasaarela ◽  
Hanna P. Lesch ◽  
Timo Tuulos ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Comparative Study ◽  
Adeno Associated Virus ◽  
Lentivirus Vectors

Recombinant adeno-associated virus 9-mediated expression of Kallistatin suppresses lung tumor growth in mice

2020 ◽  
Vol 20 ◽  
Author(s):  
Weihong Qu ◽  
Jianguo Zhao ◽  
Yaqing Wu ◽  
Ruian Xu ◽  
Shaowu Liu
Keyword(s):  
Lung Cancer ◽  
Gene Therapy ◽  
Tumor Growth ◽  
Lung Tumor ◽  
Control Group ◽  
High Dose ◽  
Blank Control Group ◽  
Adeno Associated Virus ◽  
Tumor Tissues ◽  
Subcutaneous Xenograft

Background:: Lung cancer remains the most common cause of cancer-related deaths in China and worldwide. Traditional surgery and chemotherapy do not offer an effective cure although gene therapy may be a promising future alter-native. Kallistatin (Kal) is an endogenous inhibitor of angiogenesis and tumorigenesis. Recombinant adeno-associated virus (rAAV) is considered the most promising vector for gene therapy of many diseases due to persistent and long-term transgen-ic expression. Objective:: The aim of this study was to investigate whether rAAV9-Kal inhibited NCI-H446 subcutaneous xenograft tumor growth in mice. Method:: The subcutaneous xenograft mode were induced by subcutaneous injection of 2×106 H446 cells into the dorsal skin of BALB/c nude mice. The mice were administered with ssrAAV9-Kal (single-stranded rAAV9) or dsrAAV9-Kal (double-stranded rAAV9）by intraperitoneal injection (I.P.). Tumor microvessel density (MVD) was examined by anti-CD34 stain-ing to evaluate tumor angiogenesis. Results:: Compared with the PBS (blank control) group, tumor growth in the high-dose ssrAAV9-Kal group was inhibited by 40% by day 49, and the MVD of tumor tissues was significantly decreased. Conclusion:: The results indicate that this therapeutic strategy is a promising approach for clinical cancer therapy and impli-cate rAAV9-Kal as a candidate for gene therapy of lung cancer.

scholarly journals Quantitation of Trace Levels of DNA Released from Disrupted Adeno-Associated Virus Gene Therapy Vectors

2021 ◽  
Author(s):  
Jared S. Bee ◽  
Kristin O'Berry ◽  
Yu (Zoe) Zhang ◽  
Megan Kuhn Phillippi ◽  
Akanksha Kaushal ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Adeno Associated Virus ◽  
Virus Gene ◽  
Gene Therapy Vectors

scholarly journals Bombyx mori Pupae Efficiently Produce Recombinant AAV2/HBoV1 Vectors with a Bombyx mori Nuclear Polyhedrosis Virus Expression System

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 704
Author(s):  
Qian Yu ◽  
Pengfei Chang ◽  
Xiaoxuan Liu ◽  
Peng Lü ◽  
Qi Tang ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Bombyx Mori ◽  
Nuclear Polyhedrosis Virus ◽  
Expression System ◽  
Efficient Production ◽  
Human Bocavirus ◽  
Adeno Associated Virus ◽  
Silkworm Pupae ◽  
Polyhedrosis Virus ◽  
Nuclear Polyhedrosis

Recombinant adeno-associated virus (AAV) vectors have broad application prospects in the field of gene therapy. The establishment of low-cost and large-scale manufacturing is now the general agenda for industry. The baculovirus-insect cell/larva expression system has great potential for these applications due to its scalability and predictable biosafety. To establish a more efficient production system, Bombyx mori pupae were used as a new platform and infected with recombinant Bombyx mori nuclear polyhedrosis virus (BmNPV). The production of a chimeric recombinant adeno-associated virus (rAAV) serotype 2/human bocavirus type-1 (HBoV1) vector was used to evaluate the efficiency of this new baculovirus expression vector (BEV)–insect expression system. For this purpose, we constructed two recombinant BmNPVs, which were named rBmNPV/AAV2Rep-HBoV1Cap and rBmNPV/AAV2ITR-eGFP. The yields of rAAV2/HBoV1 derived from the rBmNPV/AAV2Rep-HBoV1Cap and rBmNPV/AAV2ITR-eGFP co-infected BmN cells exceeded 2 × 104 vector genomes (VG) per cell. The rBmNPV/AAV2Rep-HBoV1Cap and rBmNPV/AAV2ITR-eGFP can express stably for at least five passages. Significantly, rAAV2/HBoV1 could be efficiently generated from BmNPV-infected silkworm larvae and pupae at average yields of 2.52 × 1012 VG/larva and 4.6 × 1012 VG/pupa, respectively. However, the vectors produced from the larvae and pupae had a high percentage of empty particles, which suggests that further optimization is required for this platform in the future. Our work shows that silkworm pupae, as an efficient bioreactor, have great potential for application in the production of gene therapy vectors.

scholarly journals Next Step in Gene Delivery: Modern Approaches and Further Perspectives of AAV Tropism Modification

Pharmaceutics ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 750
Author(s):  
Maxim A. Korneyenkov ◽  
Andrey A. Zamyatnin
Keyword(s):  
Gene Therapy ◽  
Genome Organization ◽  
Rational Design ◽  
Structural Data ◽  
Rational Approach ◽  
Tissue Tropism ◽  
Adeno Associated Virus ◽  
Chemical Conjugation ◽  
The Usa ◽  
Therapy Delivery

Today, adeno-associated virus (AAV) is an extremely popular choice for gene therapy delivery. The safety profile and simplicity of the genome organization are the decisive advantages which allow us to claim that AAV is currently among the most promising vectors. Several drugs based on AAV have been approved in the USA and Europe, but AAV serotypes’ unspecific tissue tropism is still a serious limitation. In recent decades, several techniques have been developed to overcome this barrier, such as the rational design, directed evolution and chemical conjugation of targeting molecules with a capsid. Today, all of the abovementioned approaches confer the possibility to produce AAV capsids with tailored tropism, but recent data indicate that a better understanding of AAV biology and the growth of structural data may theoretically constitute a rational approach to most effectively produce highly selective and targeted AAV capsids. However, while we are still far from this goal, other approaches are still in play, despite their drawbacks and limitations.

scholarly journals An improved method for precise genome editing in zebrafish using CRISPR-Cas9 technique

2021 ◽  
Author(s):  
Eugene V. Gasanov ◽  
Justyna Jędrychowska ◽  
Michal Pastor ◽  
Malgorzata Wiweger ◽  
Axel Methner ◽  
...  
Keyword(s):  
Genome Editing ◽  
High Efficiency ◽  
Target Site ◽  
Proof Of Concept ◽  
Intervention Site ◽  
End Joining ◽  
Guide Rna ◽  
Guide Rnas ◽  
Cas9 Nuclease ◽  
Non Homologous End Joining

AbstractCurrent methods of CRISPR-Cas9-mediated site-specific mutagenesis create deletions and small insertions at the target site which are repaired by imprecise non-homologous end-joining. Targeting of the Cas9 nuclease relies on a short guide RNA (gRNA) corresponding to the genome sequence approximately at the intended site of intervention. We here propose an improved version of CRISPR-Cas9 genome editing that relies on two complementary guide RNAs instead of one. Two guide RNAs delimit the intervention site and allow the precise deletion of several nucleotides at the target site. As proof of concept, we generated heterozygous deletion mutants of the kcng4b, gdap1, and ghitm genes in the zebrafish Danio rerio using this method. A further analysis by high-resolution DNA melting demonstrated a high efficiency and a low background of unpredicted mutations. The use of two complementary gRNAs improves CRISPR-Cas9 specificity and allows the creation of predictable and precise mutations in the genome of D. rerio.

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