Synthesis of deoxyribonucleic acid in human and hamster kidney cells infected with human adenovirus types 5 and 12

Abstract

The incorporation of 3H-labeled thymidine ( 3H-dT) into deoxyribonucleic acid (DNA) has been studied in human embryonic kidney and hamster kidney cells infected with human adenovirus types 5 and 12 (Ad5 and Ad12). The Ad5-infected human and hamster kidney cultures incorporated about 5–10 times as much 3H-dT into DNA as did uninfected cultures. The Ad12-infected human and hamster kidney cultures incorporated about 4–6 times and 3–5 times as much 3H-dT into DNA as did uninfected cultures. DNA-DNA hybridization experiments using a membrane filter technique were performed to elucidate the kind of DNA that was pulse-labeled with 3H-dT. In human and hamster kidney cells infected with Ad5, there was a progressive increase in the incorporation of 3H-dT into viral DNA. Incorporation of 3H-dT into cellular DNA was not immediately shut off. An increased incorporation during the early stage of infection (16–22 hours post infection) was followed by a decreased incorporation at later stages. The shutoff of incorporation into cellular DNA was found to occur gradually in hamster kidney cultures and rather rapidly in human kidney cultures. In human embryonic kidney cells infected with Ad12, incorporation of 3H-dT into viral DNA increased progressively until about 32 hours PI. Incorporation of 3H-dT into cellular DNA was stimulated somewhat at the early stage of infection, and was not shut off either during the period of viral DNA synthesis or for at least 20 hours after virus maturation had begun. In abortive infection of hamster kidney cells with Ad12, incorporation of 3H-dT into cellular DNA was stimulated. A small amount of incorporation of 3H-dT into viral DNA was detected at an early stage of infection. From these results, it can be concluded that in productive infection of human and hamster kidney cells by Ad5 or of human kidney cells by Ad12, cellular DNA synthesis is not immediately shut off. In abortive infection of hamster kidney cells by Ad12, cellular DNA synthesis is stimulated, whereas viral DNA is synthesized in small amounts at an early stage of infection.