Adenovirus Type 35 is a Highly Efficient Vector for Gene Transfer in CLL

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[2109] Highly Efficient Gene-Transfer into Chronic Lymphocytic

Leukemia Cells Using Adenovirus Type 35 Genetic Vectors. Session

Type: Poster Session 313-II

C. Whitacre, Farah Hedjran, Ingo Schmidt-Wolf,

Prussak, Tony Reid, J. Kipps, Whitacre s Cancer

Center, UCSD, CLL Research Consortium, La Jolla, CA, USA;

Hämatologie & Onkologie, Medizinische Universitätsklinik und

Poliklinik I, Bonn, Germany; Tragen Pharmaceuticals, San Diego, CA,

USA

Adenovirus (Ad) vectors have been used to introduce genetic material

into mammalian cells for gene-expression studies and/or gene

therapy. Ad serotypes 2 and 5, the most widely used Ad virus

vectors, belong to the group C adenoviruses, which bind to the

coxsakie/adenovirus receptor (CAR) present on cells that are most

susceptible to virus infection.

Because lymphoid cells generally do not express CAR, high-titer

virus and optimal conditions are required to infect lymphocytes,

including the neoplastic cells of most lymphoid malignancies. Ad35,

on the other hand, is a member of the group B adenoviruses that

infect cells by binding CD46, a receptor expressed on most cell

types.

We found chronic lymphocytic leukemia B cells (n = 10) expressed

high-levels of CD46 by flow cytometry, whereas none of the CLL

samples expressed CAR by immunoblot analyses.

We examined and compared the relative susceptibility of CLL cells to

infection by Ad5 versus Ad35 vectors at various multiplicity of

infection (MOI). These studies revealed that CLL cells were 100-fold

more sensitive to infection with Ad35 than with Ad5.

To examine whether this improved tropism of Ad35 for CLL cells was

due to the adenovirus receptor for CD46, we examined the relative

susceptibility of CLL cells to infection by Ad5 vectors that had

been engineered to express the Ad35 knob fiber protein (Shayakhmetov

DM, et al., J Virol 2000, vol 74, pp. 2567-83) responsible for

binding CD46, designated Ad5F35.

Titration studies evaluating for expression of a reporter transgene

in infected CLL cells (e.g. the gene encoding green fluorescence

protein (GFP)), found that Ad5F35 vectors also were > 100-fold more

effective than Ad5 vectors at transducing CLL B cells.

These studies reveal that Ad5F35 is a highly efficient vector for

transducing CLL cells, a quality that should make these vectors

better suited than Ad5 virus vectors for studies requiring gene

transfer and/or gene therapy of this and related lymphoid

malignancies.