The effect of genome editing on the development of preimplantation bovine embryos in vitro

Genome editing of preimplantation embryos of farm animals requires an efficient technology for delivering editing system components, such as CRISPR/Cas9, into the fertilized oocyte. The present study investigate the effect of the genome editing complex delivery method on the rate of embryonic development, the efficiency of targeted changes, and the level of blastocyst formation in vitro after knockout of target genes in bovine zygotes. We used two delivery methods: AAV-9 transduction and intracytoplasmic microinjection of a complex of gRNA and Cas209 RNA to knockout the CD2 and bLG genes. The obtained data showed that transduction with the AAV-2 virus serotype is less efficient in terms of knockout level and significantly affects the embryo developmental potential: the blastocyst formation level decreased to 11,3% compared to the intact control group - 50%. The method of microinjection into the cytoplasm turned out to be more effective in our experiment in terms of the yield of edited embryos and the number of formed blastocysts suitable for transfer into the uterus of recipient cows (31,1%).