Nature sub-journal: Sun Yat-sen University discovers the first method to detect ABE genome-wide off-target effects

The adenine base editor (ABE) can catalyze A-T to G-C conversion and is an important tool in the gene editing toolbox. On January 8, 2019, a research team composed of Sun Yat-sen University, Guangzhou Medical University, the Chinese Academy of Medical Sciences and some American scholars published a research paper in Nature Communications titled "Genome-wide profiling of adenine base editor specificity by EndoV-seq". The corresponding authors are Professor Huang Junjiu and Professor Song Yangzhou of Sun Yat-sen University. The study demonstrated the first detection method capable of detecting genome-wide off-target effects of ABE, and revealed possible similarities and differences between ABE and the classical Cas9 nuclease.

The research team used their independently developed EndoV-seq platform to systematically evaluate the off-target deamination of ABE across the whole genome. EndoV-seq uses endonuclease V to cleave, in vitro, the inosine-containing DNA strands generated by ABE deamination of genomic DNA. The treated DNA is then subjected to whole-genome sequencing to identify off-target sites.

Among the 8 gRNAs tested with ABE by the researchers, 2-19 (average 8.0) off-target sites were found, significantly fewer than with the classical Cas9 nuclease (7-320, average 160.7). In vivo off-target deamination was further verified by deep sequencing of target sites.

In addition, the researchers demonstrated that six different ABE-gRNA complexes can be examined in a single EndoV-seq assay. This study demonstrated the first detection method for genome-wide off-target effects of ABE, and revealed possible similarities and differences between ABE and the classical Cas9 nuclease. Original link: https://www.nature.com/articles/s41467-018-07988-z. Source: WeChat official account iNature.