Lay Summary Pigs are an important food animal species and a translational model for human disease. The development of gene editing systems such as the CRISPR/Cas9 system has greatly improved the efficiency of introducing precise genetic modifications in pigs. Although efficient, the system can introduce random DNA break in the genome and cause toxicity. To minimize the toxicity, diverse CRISPR/Cas9 systems have been developed. In this study, the efficiency and specificity of selected Cas9 variants (eSpCas9, HiFi Cas9, and LZ3 Cas9) were evaluated using swine embryos as a model. The efficiency of eSpCas9 was comparable to conventional Cas9 and could effectively suppress DNA mutations at non-target locations. In summary, the fidelity of different Cas9 variants was investigated to reduce toxicity of gene editing events without compromising on-target success in swine embryos. The findings indicate that the use of Cas9 variants can advance the field of gene editing in the livestock.
Kim et al. (Wed,) studied this question.