focus-forming virus vector containing a mutant DHFR gene were used to infect 
human bone marrow (Hock and Miller. 1986; Table Id). Up to 50% of CFU-MIX. 20% 
BFU-E. and 10% CFU-GM acquired G418 resistance after N2 infection; up to 10% of 
the CFU-GM developed MTX-resistance after infection with the DHFR vector. 
Finally. Williams et al . . (1986) demonstrated that an ADA vector could infect 
ADA" B cells. 
Studies by our group ; Using the SAX vector to infect immortalized human 
ADA-deficient T and B lymphocytes, an overall efficiency of infection of 23 to 
50% was achieved (Table Id). Southern analysis of vector-transduced populations 
which had been selected In G418 demonstrated unrearranged, intact vector 
sequences. Other vectors similar to SAX. but containing the human ADA cDNA 
gene under the control of a number of different promoters, also expressed ADA 
p 
and Neo efficiently In Immortalized ADA-deficient human R and T lymphocytes 
(Zwlebel et al.. 1986; Kantoff et al.. 1986; Kohn et al.. submitted for 
p 
publication). Expression of both the Neo and ADA genes was detected (see next 
section). In another set of experiments N2 and SAX were used to Infect human 
bone marrow cells. Following infection with N2. 0.1-2% of CFU-E, 0.1-1. 5% of 
BFU-E. and 0.1-4% of CFU-C were able to grow in the presence of G418. SAX 
Infection generally yielded a lower proportion of resistant cells. 
In summary, a number of different vectors have been shown to be able to 
Infect human hematopoietic cells, including progenitors and immortalized 
lymphocytes. It Is still unclear whether vectors will remain integrated in a 
stable fashion In humah bone marrow cells over extended periods of time. 
Additional reference material is included in Appendix A for the 
convenience of the reader. 
Recombinant DNA Research, Volume 12 
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