Gene therapy vectors derived from subgroup C adenoviruses of the serotype 5 (Ad5) and 2 (Ad2) resulted in inefficient infection of well differentiated respiratory cells, both in vitro and in vivo. The level of expression and localization of the primary receptor for Ad5 and Ad2, termed CAR, do not completely explain why the infection efficiency varies greatly in different experimental conditions. The possibility that additional receptors like proteoglycans are involved in the infection of Ad5 and Ad2 was investigated, because several pathogenic microorganisms use heparan sulfate-glycosaminoglycans (HS-GAGs) as coreceptors for multistep attachment to target cells. The HS-GAG analog heparin decreased Ad5- and Ad2-mediated infection and binding starting from the concentration of 0.1 microgram/ml, up to a maximum of 50%. A similar reduction in Ad5 binding and infection was obtained by treatment of cells with heparin lyases I, II, and III but not with chondroitin ABC lyase. The effect of heparin on Ad5 binding has not been observed in surface GAG-defective Raji cells and after treating A549 cells with heparin lyases I, II,and III. The binding of Ad5 was completely abolished when both CAR was blocked with RmcB antibody and HS-GAGs were competitively inhibited by heparin. Parallel experiments demonstrate that HS-GAGs are irrelevant to binding and infection of the subgroup B adenovirus type 3. Collectively, these results demonstrate for the first time that HS-GAGs expressed on the cell surface are involved in the binding of Ad5 and Ad2 to host cells.
Copyright 2000 Academic Press.