The invention discloses an Il21
gene knockout mouse model and a construction method and an application thereof. The construction method comprises the following steps that S1, based on the
CRISPR / Cas9 technology, a knockout area of an Il21
gene is determined, specific target sites sgRNA1 and sgRNA2 are designed according to the determined knockout area, and
gene sequences of the gRNA1 and the gRNA2 are shown in SEQ ID NO.1 and SEQ ID NO.2 respectively; S2, microinjecting active gRNA1, gRNA2 and cas9 proteins into fertilized eggs of the mouse,
transplanting the fertilized eggs survived after injection into the body of the false
pregnant female mouse, and obtaining an F0-generation mouse after the false
pregnant female mouse is pregnant and farrowing; S3,
mating the F0-generation mouse obtained in the step S2 with a wild-type mouse to obtain an F1-generation heterozygote; and S4, carrying out
inbreeding on the F1-generation heterozygote obtained in the step S3 to obtain F2-generation mice, namely the IL21
gene knockout mouse model. Based on the
CRISPR / Cas9 technology, the mouse
animal model is established by knocking out an
exon3-
exon5 region in an ENSMUST000029273.7 transcript of an IL21 gene for the first time by designing reasonable gene sequences of specific target sites gRNA1 and gRNA2, and the mouse
animal model can be applied to related research after tumor healing.