Production of mosquito cell-derived Zika virus-like particles using BacMos system

Background: Zika virus (ZIKV) is a mosquito-borne flavivirus which has been conclusively linked to Guillain-Barre syndrome and microcephaly. The worldwide emergence of ZIKV has greatly increased the demand for vaccines that reduce or prevent disease transmission. Neutralizing human antibodies which target ZIKV E proteins have been shown to prevent ZIKV replication. Virus-like particles (VLPs) lacking viral genetic material comprise self-assembled multi-subunit protein structures that are capable of strongly activating humoral and cellular immunity. Flavivirus prM and E proteins are both necessary and sufficient for the production of VLPs. Thus, it appears that ZIKV VLPs are an ideal target for vaccine design and serological detection. Methods: In this study, the BacMos (baculovirus/mosquito) method was used to introduce the ZIKV prME gene into mosquito cells. Immunofluorescence assays (IFAs), dot blot (DB) analysis, and Western blot (WB) analysis were used to evaluate the expression and secretion of ZIKV glycoproteins. VLP formation was confirmed using transmission electron microscopic (TEM) and dynamic light scattering (DLS) analysis. Results: IFA presented intense signals from ZIKV E-positive cells in BacMos-ZIKV prME-transduced cells. DB and WB detected abundant ZIKV glycoproteins in the culture medium of BacMos-ZIKV prME-transduced cells. TEM observation and DLS analysis revealed that ZIKV VLPs comprised spherical particles, with an average diameter of 30 nm. Conclusions: Mosquito cell-derived ZIKV VLPs are promising candidates for the development of safe, efficacious vaccines and diagnostic antigens in the future.