Construction of chicken x human microcell hybrids for human gene targeting

Human chromosomes 1, 2, 3, and 11 were tagged with pSV2 neo and transferred via microcell fusion from mouse A9 human monochromosomal hybrids to a chicken pre-B cell line, DT40, proficient for homologous recombination. Hybrids containing two copies of human chromosome 11 were transfected with targeting vectors containing a mammalian selectable gene with either the D11S16 or HRAS genomic sequences corresponding to two different chromosome 11 loci. Analysis of stable transfectants showed a high frequency (approximately 80%) of targeted integration of these constructs into each of the homologous loci of human chromosome 11 in DT40 hybrids. The results suggest that any human genomic sequences on human chromosomes transferred into DT40 cells could be targeted at high frequency, thereby allowing for subsequent modification of human genes and chromosomes.