Adenovirus Type 5 Substituted with Type 11 or 35 Fiber Structure Increases its Infectivity to Human Cells Enabling Dual Gene Transfer in CD46-dependent and -independent Manners

Infectivity of adenovirus type 5 (Ad5) to cells depends primarily on its fiber-mediated binding to the coxsackievirus and adenovirus receptor (CAR) on target cells. Down-regulated CAR expression, often found in human tumors, hampered Ad5-mediated gene transfer. Ad 11 and Ad 35, belonging to a subtype B group, use CD46 as their cellular receptors; accordingly, chimeric Ad5 whose fiber structure was substituted with that of the type 11 or 35 (Ad5/11 or Ad5/35) could infect human cells in a different manner from Ad5. We found that Ad5/35 infected human tumors, including pancreatic and breast cancer, and human fibroblasts better than Ad5 and Ad5/11. Infectivity of Ad5/35 to these cells was correlated with that of Ad5/11, but efficacy of Ad5/35- and Ad5/11-mediated transduction was not directly correlated with the expression level of CD46 in the target cells. Infection of human hepatoma cells with measles virus, whose cellular receptor is CD46, down-regulated the CD46 expression and reduced subsequent infectivity of Ad5/35 but not Ad5/11. Infection of Ad5 suppressed subsequent gene transfer by Ad5 but not by Ad5/11 or Ad5/35. Likewise infection of Ad5/35 decreased following gene transduction by Ad5/35 and Ad5/11, but to a lesser extent by Ad5. These data collectively showed that combinatory use of Ad5 and the chimeric Ad enables dual gene transfer into target cells and suggest that infectivity of subtype B Ad does not completely depend on CD46 expression and that other receptors possibly influence the infectivity.