Ebola virus
infections lead to severe hemorrhagic
fevers in humans and nonhuman primates; and human fatality rates are as high as 67%-90%. Since the Ebola virus was discovered in 1976, the only available treatments have been medical support or the emergency administration of experimental drugs. The absence of licensed
vaccines and drugs against the Ebola virus impedes the prevention of
viral infection. In this study, we generated recombinant baculoviruses (rBV) expressing the Sudan virus (SUDV) matrix structural
protein (VP40) (rBV-VP40-VP40) or the SUDV
glycoprotein (GP) (rBV-GP-GP), and SUDV virus-like particles (VLPs) were produced by
co-infection of Sf9 cells with rBV-SUDV-VP40 and rBV-SUDV-GP. The expression of SUDV VP40 and GP in SUDV VLPs was demonstrated by IFA and Western blot analysis. Electron microscopy results demonstrated that SUDV VLPs had a filamentous morphology. The immunogenicity of SUDV VLPs produced in insect cells was evaluated by the immunization of mice. The analysis of antibody responses showed that mice vaccinated with SUDV VLPs and the adjuvant
Montanide ISA 201 produced SUDV GP-specific
IgG antibodies. Sera from SUDV VLP-immunized mice were able to block
infection by SUDV GP pseudotyped HIV, indicating that a
neutralizing antibody against the SUDV GP
protein was produced. Furthermore, the activation of B cells in the group immunized with VLPs mixed with
Montanide ISA 201 was significant one week after the primary immunization. Vaccination with the SUDV VLPs markedly increased the frequency of
antigen-specific cells secreting type 1 and type 2
cytokines. To study the
therapeutic effects of SUDV
antibodies, horses were immunized with SUDV VLPs emulsified in Freund's complete adjuvant or Freund's incomplete adjuvant. The results showed that horses could produce SUDV GP-specific
antibodies and
neutralizing antibodies. These results showed that SUDV VLPs demonstrate excellent immunogenicity and represent a promising approach for
vaccine development against SUDV
infection. Further, these horse anti-SUDV purified
immunoglobulins lay a foundation for SUDV therapeutic drug research.