CXADR and infection: The first step in infection by many human adenoviruses, including the subgroup C serotypes 2 and 5 most commonly used in gene therapy applications, is the high-affinity binding of the knob domain of the fibre protein (Henry et al, 1994; Louis et al, 1994) to the primary cellular receptor, the coxsackievirus and adenovirus receptor (CAR).