Quantitative RT-PCR to determine the amount of mRNA synthesized for the reporter genes during the transfection and infection assays was performed according to Vester et al. [19] . Briefly, following the removal of the cell culture medium, cells were washed with PBS and lysed by incubation with TriZol reagent (Invitrogen) for 3 min at room temperature. The lysates were mixed with chloroform and centrifuged at 14,000 rpm for 20 min at 4uC. The water phase was collected and mixed with 70% (v/v) ethanol. Subsequent RNA purification was performed using the RNAeasy Kit (Qiagen) according to the manufacturer's protocols. The concentration of total RNA was determined using NanoDrop 1000 Spectrophotometer (Thermo Scientific). The total RNA was treated with amplification grade DNase (Invitrogen) according to the manufacturer's protocols to digest the plasmid DNA. Reverse transcription from total RNA was performed using mRNA-specific primer ( Table 2) . Reverse transcription was carried out using Superscript II reverse transcriptase (Invitrogen). Briefly, 100 ng of DNase-treated total RNA was mixed with 2 pmol of primer and 1 ml of 25 mM dNTP in the total volume of 12 ml. The mixture was incubated at 65uC for 5 min. After the cooling step to 4uC, 4 ml of 56 first strand buffer, 2 ml of 0.1 M DTT, 1 ml of RNase Inhibitor (40 U/ml) were added and the mixture was incubated at 42uC for 2 min. Reverse transcription was carried out at 42uC for 50 min after addition of 1 ml superscript II reverse transcriptase (50 U/ml) and was terminated by heating at 70uC for 15 min. Real time quantitative PCR was performed using qPCR MasterMix Plus for SYBR Green (Eurogentech) on a LightCycler 480 II (Roche). qPCR forward and reverse primers ( Table 2 ) that primed at the coding sequence of corresponding reporter gene were used to amplify cDNA. Quantitative PCR reactions were set up in triplicates according to the manufacturer's instruction by mixing 20 pmol of forward and reverse primers and 1 ml of cDNA products. The PCR mixture was incubated at 95uC for 10 min, followed by 40 cycles of 15 sec and 1 min incubations at 95uC and 60uC, respectively. To check the specificity of PCR product, melting curve analysis was performed at the end of the PCR. The comparative Ct method was used to determine the relative mRNA levels using the housekeeping gene GAPDH as a reference [38, 39] . The mRNA levels were normalized relative to the samples in which a single reporter construct was transfected.