Cellular DNA synthesis in productive infection with adenoviruses.

Abstract

AbstractThe effect of adenoviruses on cellular DNA synthesis in productive infection of hamster kidney cells and human embryonic lung cells was studied.(1) Treatment with 5‐fluorouracil (FU) strongly reduced incorporation of 3H‐dT into DNA of uninfected hamster kidney cultures. Under such conditions, the amount of incorporation of 3H‐dT into DNA in FU‐treated Ad5‐infected cultures was about one‐third of that observed in untreated ones. Analysis by DNA‐DNA hybridization revealed that the major proportion of newly synthetized 3H‐DNA was cellular between 16 to 32 h after infection in FU‐treated infected cultures. Synthesis of viral DNA and infectious virus was slightly delayed and reduced in FU‐treated cells.(2) With the aim of keeping the specific activities of 3H‐dT derivatives in acid‐soluble pools in cells as constant as possible, long‐term labelling of DNA with 3H‐dT after infection was carried out, in the presence of aminopterin, hypoxanthine and glycine to prevent endogenous biosynthesis of thymidylic acid. Incorporation of 3H‐dT into cellular DNA was much greater in infected than in uninfected cultures after labelling for 24 h. These results strongly suggest that cellular DNA synthesis was induced in productive infection of hamster kidney cells by Ad5.(3) Infection of monolayer cultures of human embryo lung (HEL) cells with adenovirus types 2, 3, 4, 5 and 12 (Ad2, Ad3, Ad4, Ad5 and Ad12) resulted in productive infection with delayed cytopathic effect (CPE).3H‐dT uptake into DNA was stimulated in contact‐inhibited HEL cells by infection. Apparent increase in incorporation of 3H‐dT into cellular DNA was detectable for a long period in infected cultures, suggesting that induction of cellular DNA synthesis took place by infection. Thus the time of appearance of CPE seems to be correlated with the period during which induction of cellular DNA synthesis is detectable.