<i>IL2RG</i> deficient X-SCID pigs generated via electroporation-mediated gene editing using CRISPR/Cas9

Interleukin 2 receptor gamma (IL2RG) knockout (KO) is frequently used to generate X-linked severe combined immunodeficiency (X-SCID) models. Humans and pigs have anatomical and physiological similarities; hence, X-SCID pigs are being actively developed. IL2RG KO X-SCID pigs are typically achieved through somatic cell nuclear transfer using genetically modified somatic cells as nuclear donors. Therefore, we investigated the possibility of generating IL2RG KO pigs through electroporation-mediated zygotic gene editing using CRISPR/Cas9. First, we designed and selected an efficient guide RNA targeting the porcine IL2RG gene. Subsequently, we obtained one mosaic mutant male piglet carrying a frame-shift mutation (-19 bp) in IL2RG without off-target events, after the transfer of gene-edited zygotes. We also confirmed that F1 female pigs successfully inherited the -19bp mutation (XKOX). Subsequently, we obtained 30 offspring, including 10 IL2RG-KO male pigs (XKOY), from three F1 XKOX litters. The XKOY pigs showed thymic tissue hypoplasia, and flow cytometry analysis revealed absence of cytotoxic T lymphocytes, helper T, and natural killer cells. Typically, X-linked disorders predominantly affect males. Therefore, female carriers pigs are usually maintained and mated with WT males, generating animal models of the disease. In this study, we successfully generated IL2RG-modified F0 male hemizygous pigs rescued by mosaic genotype via electroporation-mediated zygotic gene editing and subsequently generated IL2RG KO pigs by mating F0 pigs with WT females. Our results demonstrated the feasibility of using zygote electroporation to generate IL2RG-deficient pigs. Furthermore, while obtaining a fertile IL2RG mosaic male pig capable of transmitting the mutation was serendipitous, it presents a potential alternative approach for generating X-linked immunodeficiency models.