Introducing a cleavable signal peptide enhances the packaging efficiency of lentiviral vectors pseudotyped with Japanese encephalitis virus envelope proteins.

Research into the properties of Japanese encephalitis virus (JEV) has been facilitated by use of pseudotyped viruses. The signal peptide is a key determinant for membrane targeting and membrane insertion, which could affect packaging of pseudotyped viruses. In this study, we generated three lentiviral vectors pseudotyped with JEV envelope proteins that co-express either a strong signal peptide from vesicular stomatitis virus (VSV)-G (VSVMEpv) or a weak signal peptide of JEV (SPMEpv), or a virus without a signal peptide in front of the JEV prM/E (MEpv). Western blot demonstrated that JEV E protein and HIV p24 were present in the same particles of the three pseudotyped JEV-E based lentiviral vectors. Electron microscopy revealed that the three pseudotyped JEV-E based lentiviral vectors were 120-180nm in diameter. Real-time quantitative reverse transcriptase polymerase chain reaction showed that the titer of VSVMEpv was 17-fold higher than that of MEpv, while the titer of SPMEpv was six-fold higher than that of MEpv. Inclusion of a signal peptide enhanced packaging efficiency of pseudotyped JEV-E based lentiviral vectors. With a strong signal peptide helping they generate a higher number of viral particles. Green fluorescent protein and luciferase expression showed that the transduction titer or relative fluorescence units of VSVMEpv, SPMEpv and MEpv were not significantly different. We suggest that the signal peptide does not influence the infectivity of pseudotyped JEV-E based lentiviral vectors. In addition, our findings indicated that pseudotyped JEVs show preferential tropism for BHK-21 cells, supporting the mimic function displayed by parental JEV. Therefore, our study provided a cost-effective method to generate pseudotyped JEV-E based lentiviral vectors, which may represent a valid model to investigate some of the infectious properties of JEV.