A DNA-based West Nile virus replicon elicits humoral and cellular immune responses in mice.

While self-replicating, non-infectious subgenomic flavivirus replicons have been described, most of them are RNA transcripts under the control of an Sp6 or T7 promoter. In this study, using West Nile virus (WNV) as a model, a series of DNA-based reporter replicons under the control of a minimal cytomegalovirus (CMV) immediate-early promoter were constructed, and functional analysis showed that these reporter replicons replicate efficiently in mammalian cells. When the DNA-based WNV replicon was used to immunize mice, NS1-specific IgG antibodies and anti-WNV neutralizing antibodies were both induced. Additionally, immunization with this DNA-based WNV replicon induced high levels of lymphocyte proliferation and enhanced the secretion of IFN-γ. These results suggest that this type of DNA-based replicon can induce humoral and cellular immune responses in mice, indicating that this type of DNA-based replicon may serve as a useful platform for vaccine development and protein expression.