“…With Ad41, an average of one infectious virus particle was found to be sufficient to productively infect each 293 cell (Tiemessen & Kidd, 1990). However, reports of loss of infectivity upon passage of Ad41 in 293 cells (D. Pieniazek et al, 1990a) and poor growth of Ad40 in these cells (Chiba et al, 1983;Uhnoo et al, 1983;Brown, 1985;van Loon et al, 1985) suggest that the provision of E1 functions alone is not sufficient to overcome growth restriction.…”