Genome editing of CCR5 by CRISPR-Cas9 in Mauritian cynomolgus macaque embryos

The discovery that CCR5 serves as an R5-HIV-1 co-receptor, coupled with findings of protection from HIV infection in individuals lacking CCR5, led to the exploration of novel therapeutic strategies for HIV infection based on genome editing of CCR5. Advancing translation of CCR5-mutant-based cellular therapies for HIV requires development of novel physiologically relevant animal models. Mauritian cynomolgus macaques (MCMs), with high degree of MHC allele sharing, are valuable models for HIV-1 research and stem cell therapies. To facilitate the generation of a CCR5-mutant MHC-defined MCM model, we explored editing the CCR5 gene in MCM embryos via CRISPR-Cas9. We refined ovarian stimulation and in vitro fertilization (IVF) methods established for Chinese cynomolgus macaques to generate in vitro MCM embryos. Time-lapse embryo imaging was performed to assess the timing of MCM embryonic developmental events in control and CRISPR-Cas9 microinjected embryos. Using a dual-guide gene targeting approach, biallelic deletions in the CCR5 gene were introduced into similar to 23-37% of MCM embryos. In addition, single blastomere PCR analysis revealed mosaicism in CCR5 editing within the same embryo. Successful development of IVF and CCR5 editing protocols in MCM embryos lays a foundation for the creation of CCR5-mutant MCMs to assess novel stem cell-based HIV therapeutics.