ADENOASSOCIATED VIRUS TYPE 2-MEDIATED TRANSDUCTION IN PRIMARY HUMAN BONE-MARROW-DERIVED CD34(- DONOR VARIATION AND CORRELATION OF TRANSGENEEXPRESSION WITH CELLULAR-DIFFERENTIATION() HEMATOPOIETIC PROGENITOR CELLS )

Although the adeno-associated virus type 2 (AAV) is known to possess a broad host range that transcends the species barrier, we suggested in an earlier study that AAV infection of human cells is receptor mediat ed (S. Ponnazhagan et al., J. Gen. Virol. 77:1111-1122, 1996). In the present studies, we investigated the ability of AAV to infect primary human hematopoietic progenitor cells capable of multilineage different iation, Bone marrow-derived CD34(+) cells from 12 hematologically norm al volunteer donors were infected with a recombinant AAV containing th e beta-galactosidase gene under the control of the cytomegalovirus imm ediate-early promoter (vCMVp-lacZ), Whereas 15 to 80% of the cells fro m approximately 50% of the donors showed various levels of lacZ gene e xpression, the expression was undetectable in cells from the remaining donors, However, if cells from both sets of donors were stimulated wi th various combinations of cytokines to induce differentiation into my eloid and lymphoid lineages following AAV infection, then the level of expression of the transduced gene increased up to 20-fold over a peri od of 14 days, The results of virus-binding assays suggested that the observed difference between the two groups was due to the differential susceptibility of CD34(+) cells to AAV infection rather than to diffe rences in transcription and translation of the transduced gene, To cor roborate these results, CD34(+) cells from the two donor groups, KB (h uman nasopharyngeal carcinoma) cells, and M07e (human megakaryocytic l eukemia) cells were infected with vCMVp-lacZ. KB cells served as a pos itive control for AAV infection, and M07e cells served as a negative c ontrol, Whereas abundant hybridization to the single-stranded viral DN A on Southern blots was detected in KB and CD34(+) cells that were pos itive for lacZ gene expression, little activity was detected in M07e a nd CD34(+) cells that did not show expression of the lacZ gene, These results suggest that the levels of expression of the putative cellular receptor for AAV vary widely in CD34(+) cells from different donors. These studies have implications for the potential use of AAV vectors i n human gene therapy involving primary human primitive hematopoietic s tem and progenitor cells.