• Vaccine Name: VRP expressing VP24
• Target Pathogen: Ebola virus
• Target Disease: Ebola hemorrhagic fever
• Vaccine Ontology ID: VO_0000781
• Type: VEEV replicon
• VP24 from Zaire ebolavirus gene engineering:
  • Type: Protein
  • Description:
  • Detailed Gene Information: Click Here.
• Preparation: Replicon RNAs were packaged into particles. Briefly, capped replicon RNAs were produced in vitro by T7 runoff transcription of NotI-digested plasmid templates using the RiboMAX T7 RNA polymerase kit. BHK cells were cotransfected with the replicon RNAs and two RNAs expressing the VEE virus structural proteins. The cell culture supernatants were harvested approximately 30 h after transfection and the replicon particles were concentrated and partially purified by centrifugation through a 20% sucrose cushion. Packaged VRPs were suspended in phosphatebuffered saline and titers were determined as immunofluorescent foci after infection of Vero cells as described using either EBOV-immune rabbit serum or mouse monoclonal antibodies to VP24 (Z-AC01-BG11-01), VP35 (M-HC01-AF11), or VP40 (M-HD06-AD10) (Wilson et al., 2001).
• Virulence:
• Description: VP24 is an Ebola virus protein. It is membrane associated and is most likely located on the inside of the membrane. The function of VP24 is not known but it may serve as a minor matrix protein, facilitating the interaction of VP40 and/or GP with the RNP complex, or function in the uncoating of the virion during infection (Wilson et al., 2001).

Mouse Response

• Host Strain: BALB/c and C57BL/6
• Vaccination Protocol: Groups of 10 BALB/c or C57BL/6 mice per experiment were subcutaneously injected at the base of the neck with 2(10^6) focus-forming units of VRPs encoding the EBOV-Z genes, or with a control replicon encoding the Lassa N gene. Booster immunizations were administered at 1-month intervals (Wilson et al., 2001).
• Persistence: None noted
• Side Effects: None noted
• Efficacy: Vaccination with VRPs encoding the EBOV-Z VP24 protein protected the majority (90±95%) of the BALB/c mice from lethal EBOV challenge. In a similar experiment, two inoculations of VRPs encoding the EBOV-Z VP24 protein also protected 5/5 BALB/c mice from a 3(10^4) LD50 challenge dose and 5/5 BALB/c mice from a 3(10^6) LD50 challenge dose. None of the C57BL/6 mice were protected. Most of the mice had detectable EBOV-Z-specific serum antibodies after vaccination with VRPs encoding the EBOV-Z VP protein (Wilson et al., 2001). These results indicate that the VP24 protein may be an important component of a vaccine designed to protect humans from Ebola hemorrhagic fever.