HIGH-FREQUENCY RECOMBINATION BETWEEN LOXP SITES IN HUMAN-CHROMOSOMES MEDIATED BY AN ADENOVIRUS VECTOR EXPRESSING CRE RECOMBINASE

An adenovirus vector (AdCre1) expressing Cre recombinase has been used to induce recombination between loxP sites in human chromosomes. G418 resistant cells with one loxP site, generated by transfection with a plasmid containing loxP between tile SV40 promoter and the G418 resist ance (neo) gene, were infected with AdCre1 and transfected with a plas mid containing loxP adjacent to a promoterless hisD gene. This resulte d in integration of hisD downstream of the SV40 promoter with gain of histidinol and loss of G418 resistance. Since AdCre1 is non-replicatin g and Cre expression transient, histidinol resistant cells containing the hisD gene flanked by loxP sites were stable. Reinfection of these cells with AdCre1 induced excision of hisD in over 90% of infected cel ls. This high efficiency of site-specific recombination suggests that AdCre1 may be exploited for temporal and tissue-specific regulation of gene expression and for chromosome engineering in vitro and in animal s.