Biochemical consequences of type 2 adenovirus and Simian virus 40 double infections of African green monkey kidney cells.

African green monkey kidney (AGMK) cells were nonpermissive hosts for type 2 adenovirus although the restriction was not complete; when only 3 plaque-forming units/cell was employed as the inoculum, the viral yield was about 0.1% of the maximum virus produced when simian virus 40 (SV40) enhanced adenovirus multiplication. The viral yield of cells infected only with type 2 adenovirus increased as the multiplicity of infection was increased. Type 2 adenovirus could infect almost all AGMK cells in culture; adenovirus-specific early proteins and DNA were synthesized in most cells, but small amounts of late proteins were made in relatively few cells. Even when cells were infected with both SV40 and adenovirus, only about 50% were permissive for synthesis of adenovirus capsid proteins. Approximately the same quantity of adenovirus deoxyribonucleic acid (DNA) was synthesized in the restricted as in the SV40-enhanced infection. However, in cells infected with SV40 and type 2 adenovirus, replication of SV40 DNA was blocked, multiplication of SV40 was accordingly inhibited, and synthesis of host DNA was not stimulated. To enhance propagation of type 2 adenovirus, synthesis of an early SV40 protein was essential; 50 mug of cycloheximide per ml prevented the SV40-induced enhancement of adenovirus multiplication, whereas 5 x 10(-6)m 5-fluoro-2-deoxyuridine did not abrogate the enhancing phenomenon.