Effect of cordycepin on Hantaan virus 76-118 infection of primary human embryonic pulmonary fibroblasts--characterization of apoptotic effects

The cDNA microarray technique was used to study gene epression in human embryonic pulmonary fibroblasts (HEPF) infected with Hantaan virus (HTNV) under the influence of cordycepin (Cor), an inhibitor of post-transcriptional pre-mRNA polyadenylation. Four apoptotic genes, the insulin-like growth factor binding protein 1, NFkB inhibitor alpha, caspase-3 and NFkB1 were up-regulated in both infected and uninfected Cor-treated cells and two cell cycle-associated genes, CDC-like kinase and beta-induced transforming growth factor were up-regulated in Cor-untreated cells but down-regulated in Cor-treated cells. Cell morphology examination, quantitative RT-PCR, and immunofluorescence (IF) test suggested that following the Cor treatment the HTNV infection took place, but late viral gene expression was slightly reduced. Three parameters, namely caspase-3 activity, annexin V binding, and cell cycle were used to detect apoptosis. The results suggested that the induction of apoptosis in HEPF by HTNV started at 6 hrs post infection (p.i.). Following the Cor treatment, however, the caspase-3 activity began to increase at 24 hrs p.i. Thus it is suggested that inhibition of de novo late viral protein synthesis by Cor changes the apoptosis pathway and cell cycle by delaying caspase-3 gene expression and by up/down-regulating of expression of other apoptotic and cell cycle-associated genes. This implicates that HTNV can induce apoptosis in HEPF even without de novo viral protein synthesis and with a reduced and slowed viral maturation.