Dengue virus type 2 induces apoptosis of RAW264.7 cells and effect of apoptosis on virus replication

AIM:To explore the apoptotic pathway in dengue virus type 2 (DENV2)-infected RAW264.7 cells and to analyze the effect of apoptosis on virus replication. METHODS:RAW264.7 cells were infected with DENV2. MTT assay was used to detect the cell viability. Apoptosis was assessed by Hoechst 33342 staining and Annexin V-FITC/PI staining. The expression levels of caspase-3 and caspase-8 were determined by Western blotting. The activity of caspase-9 was measured with a colorimetric kit. Mitochondrial membrane potential was evaluated using JC-1 fluorescent staining. TCID50 was used to estimate the infectious virion concentration after using Z-VAD-FMK to inhibit apoptosis. RESULTS:The viability of RAW264.7 cells decreased after DENV2 infection at 24 h, 36 h and 48 h. Karyopyknosis in dengue virus-infected cells was observed. The protein levels of caspase-3 and caspase-8 and the activity of caspase-9 increased in the apoptotic cells after dengue virus infection. Mitochondrial membrane potential was reduced after dengue virus infection. There was a higher virion concentration in the cell culture medium after inhibition of apoptosis. CONCLUSION: Dengue virus induces apoptosis of RAW264.7 cells. Apoptotic inhibition of RAW264.7 cells facilitates the production of dengue virus.