Making targeted transgenic mice
Transgenic mice have been made for more than 20 years, however to construct a mice that have a targeted gene deletion (knock-out) or insertion (knock-in) which is under the control of endogenous promotors the strategy is somewhat more complicated. The targeting vector is dependent on homologous recombination to be inserted in the genome and electroporation of cultured ES cells are used as compared to microinjection of DNA straight into fertilized eggs. After electroporation, the ES cells must be screened by Southern blotting and PCR to obtain the correct clone. Thus, the making of a targeted transgenic mouse involves 3 major steps, 1) Make a targeted gene construction, 2) Transfection into embryonic stem (ES) cells and screening, 3) Transfer correct ES cell clone into the blastocyst of a pseudopregnant mouse and backcross to inbred strain.

 In the MOPC315 system we would like to make several immunoglobulin knock-in and conditional knock-out mice for various projects and we are currently working on making 3 different knock-in mice. Klaus Rajewsky at Harvard Medical School, which was a pioneer and still leading in this field, is an appreciated collaborator.