A novel Cre recombinase reporter mouse strain facilitates selective and efficient infection of primary immune cells with adenoviral vectors.

Replication-deficient recombinant adenoviruses are potent vectors for the efficient transient expression of exogenous genes in resting immune cells. However, most leukocytes are refractory to efficient adenoviral transduction as they lack expression of the coxsackie/adenovirus receptor (CAR). To circumvent this obstacle, we generated the R26/CAG-CARΔ1(StopF) (where R26 is ROSA26 and CAG is CMV early enhancer/chicken β actin promoter) knock-in mouse line. This strain allows monitoring of in situ Cre recombinase activity through expression of CARΔ1. Simultaneously, CARΔ1 expression permits selective and highly efficient adenoviral transduction of immune cell populations, such as mast cells or T cells, directly ex vivo in bulk cultures without prior cell purification or activation. Furthermore, we show that CARΔ1 expression dramatically improves adenoviral infection of in vitro differentiated conventional and plasmacytoid dendritic cells (DCs), basophils, mast cells, as well as Hoxb8-immortalized hematopoietic progenitor cells. This novel dual function mouse strain will hence be a valuable tool to rapidly dissect the function of specific genes in leukocyte physiology.