Objective: To observe the effect of human cytomegalovirus infection on the host cellular DNA synthesis and expression of cyclones.
Methods: HCMV infected cell was established in vitro by incubating passage cultured HEL and HCMV AD169 strain with different titres. The cells were synchronized in the G0/G1 stage by contact inhibition and infected with strain AD169 of HCMV at an MOI of 5 PFU per cell. We harvested infected cell at different time 0 h, 3 h, 6 h, 24 h, 72 h and 96 h post infection. Then the cell cycle progress was measured. Meanwhile, the DNA content and expression of proteins of cycline E, cycline A and cycline D1 were determined with FCM and Western Blot respectively.
Results: We found that the amount of S stage cell infected by HCMV had increased dramatically, and that of G2/M stage cell reduced during 24 h-96 h PI, and no G2/M stage cell was detected within 96 h PI. The content of 2N DNA maintained unchangeable for 24 h after infection and the content of total DNA in infected cells began to increase within 48 h PI, and the substantial cell with 2N DNA were observed 72 h after infection. However, DNA content was not altered in control group of normal HEL and HCMV PAA group. CyclinE protein was induced 12 h PI and peak induction occurred 24 h PI in contact-inhibited cells. CyclinA protein expression was not induced in HCMV infected density-arrested cells. The abundance of cyclinD1 decreased 24 h PI.
Conclusion: The expression of cyclinE and activity of cyclinE/Cdk2 kinase are increased obviously in G0/G1 stage cells infected with HCMV, which may induce the cell cycle to overpass G1/S restriction point and make the cell cycle arrested in later G1 stage. HCMV can not activate cellular DNA synthesis, and increase of total DNA content in infected cells result from the viral DNA replication.