• Vaccine Ontology ID: VO_0000785
• Type: DNA vaccine
• GP from Reston ebolavirus gene engineering:
  • Type: DNA vaccine construction
  • Detailed Gene Information: Click Here.
• Vector: pCMV (Xu et al., 1998)
• Preparation: Plasmids containing the sGP cDNAs are used to subclone the relevant inserts into CMV expression vectors, which utilize the bovine growth hormone polyadenylation sequence. The plasmid pCRII-sGP is digested with EcoRI and treated with Klenow enzyme, and the resulting fragment is inserted into the BamHI/Bg/II CMV plasmid, which has been incubated with Klenow fragment and calf intestinal phosphate (CIP), and phenol chloroform extracted (Xu et al., 1998).
• Description: sGP is a secreted or transmembrane form of glycoprotein (Xu et al., 1998).

• Vaccine Ontology ID: VO_0000780
• Type: Recombinant vector vaccine
• GP from Reston ebolavirus gene engineering:
  • Type: Protein
  • Detailed Gene Information: Click Here.
• Vector: VRP: VEE replicon particle
• Preparation: The Ebola GP genes from the Mayinga strain of Ebola virus were derived from pGEM3Zf(-)-based plasmid. The BamHI±KpnI (2.4 kb) fragment containing the GP gene was subcloned into a shuttle vector. From the shuttle vector, GP gene was transferred as ClaI-fragment into the ClaI site of the replicon clone, resulting in plasmids encoding the GP gene in place of the VEE structural protein genes (Pushko et al., 2000).
• Virulence:

• Vaccine Ontology ID: VO_0011387
• Type: Recombinant vector vaccine
• Status: Research
• EBOV NP gene engineering:
  • Type: Recombinant vector construction
  • Detailed Gene Information: Click Here.
• Vector: VRP: VEE replicon particle
• Preparation: The Ebola NP gene from the Mayinga strain of Ebola virus were derived from pSP64-based plasmid. The BamHI±EcoRI (2.3 kb) fragment containing the NPgene, was subcloned into a shuttle vector digested with BamHI and EcoRI within a polylinker sequence flanked by ClaI sites. From the shuttle vector, NP gene was transferred as ClaI-fragments into the ClaI site of the replicon clone, resulting in plasmids encoding the NP gene in place of the VEE structural protein genes (Pushko et al., 2000).
• Immunization Route: Intramuscular injection (i.m.)

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: VRP were diluted in PBS and administered to 6±8 week old BALB/c mice. Groups of 10 BALB/c mice were inoculated on days 0 and 28 with two doses of NP-VRP, GP-VRP, or a mixture of both. Challenge was carried out 4 weeks after final immunization with VRP. Mice were challenged i.p. with mouse-adapted Ebola virus. To determine subsequent viral titers in the serum, liver, and spleen, two mice were taken from VRP-vaccinated or control groups on each of days 1±5 after challenge, anesthetized and exsanguinated. Portions of the liver and spleen were removed aseptically, weighed, and ground in a sterile mortar. Viral titers in the sera and tissues were determined by plaque assay (Pushko et al., 2000).
• Persistence: None noted
• Side Effects: None
• Efficacy: GP-VRP was effective in protecting BALB/c mice against a lethal challenge with mouse-adapted Ebola virus (Pushko et al., 2000). Nine out of ten animals vaccinated with GP-VRP were protected (Pushko et al., 2000).

Mouse Response

• Host Strain: BALB/c
• Vaccination Protocol: VRP were diluted in PBS and administered to 6±8 week old BALB/c mice. Groups of 10 BALB/c mice were inoculated on days 0 and 28 with two doses of NP-VRP, GP-VRP, or a mixture of both. Challenge was carried out 4 weeks after final immunization with VRP. Mice were challenged i.p. with mouse-adapted Ebola virus. To determine subsequent viral titers in the serum, liver, and spleen, two mice were taken from VRP-vaccinated or control groups on each of days 1±5 after challenge, anesthetized and exsanguinated. Portions of the liver and spleen were removed aseptically, weighed, and ground in a sterile mortar. Viral titers in the sera and tissues were determined by plaque assay (Pushko et al., 2000).
• Efficacy: NP-VRP was effective in protecting BALB/c mice against a lethal challenge with mouse-adapted Ebola virus (Pushko et al., 2000). All mice vaccinated with NP-VRP survived the challenge with no signs of illness (Pushko et al., 2000).

Guinea pig Response

• Vaccination Protocol: Two groups of guinea pigs were immunized by injection of 0.5 mg/ml in each hind leg (two injections at each time point) with the plasmed expression vectors. Animals were challenged by inoculation with a stock of Ebola virus that had been passaged once in Vero E6 cells and serially passaged by intraperitoneal injection of slpeen homogenates in Hartley guinea pigs seven times. Immunized guinea pigs were injected intraperitoneally with 0.5 ml of a 1:1000 dillution of spleen cell homogenate in Hanks' balanced salt solution 122 days after the initial plasmid DNA injection. Survival was determined 10 days later at which times animals were killed for serologic and pathologic analysis (Xu et al., 1998).
• Persistence: None noted
• Immune Response: A broad immune response was conferred by sGP which induced both cellular and humoral immunity to the membrane-associated GP. The ability of vectors expressing GP to confer immunity may be explained by the generation of the lower molecular weight degradation products, which could provide sufficient protein for antigen presentation to induce detectable, cellular and humoral immune responses in guinea pigs (Xu et al., 1998).
• Side Effects: None noted
• Efficacy: For the first group of 6 giunea pigs, animals were challenged within 2 months after the initial immunization. Five of six of the immunized subjects survived in contrast to 0/6 control subjects. In the second group, guinea pigs were challenged 4 months after the initial immunization. Three of the five guinea pigs immunized with sGP showed no ill effects following the viral challenge (Xu et al., 1998).

Guinea pig Response

• Host Strain: strain 2 and strain 13
• Vaccination Protocol: VRP were diluted in PBS and administered to inbred, strain 2 or strain 13 guinea pigs. Groups of five guinea pigs were inoculated subcutaneously (s.c.) at day 0 with a total of 0.5 ml containing 10^7 IU VRP at one (strain 2) or two (strain 13) dorsal sites. Challenge was carried out 4 weeks after final immunization with VRP. Guinea pigs were challenged s.c. with 1000 LD50 of guinea pig- adapted Ebola virus. Animals were observed daily for 60 days, and morbidity (determined as changes in behavior, appearance, and weight) and survival were recorded. Blood samples were taken
  on the days indicated after challenge and viremia levels were determined by plaque assay (Pushko et al., 2000).
• Persistence: None noted
• Side Effects: None noted
• Efficacy: At day 7 after challenge, both VRP-vaccinated groups had lower viremia titers than control animals. All mockvaccinated animals or NP-VRP-vaccinated animals became ill, and died at days 8±11 after challenge. However, three out of five guinea pigs vaccinated with GP-VRP showed no signs of illness and survived challenge, and the remaining two showed increased survival times. No clear relationship with survival and antibody titers was observed, as the pre-challenge ELISA and PRNT50 titers of the two GP-VRP-inoculated animals that died were equivalent to those of the three survivors (Pushko et al., 2000).

Guinea pig Response

• Host Strain: strain 2 and strain 13
• Vaccination Protocol: VRP were diluted in PBS and administered to inbred, strain 2 or strain 13 guinea pigs. Groups of five guinea pigs were inoculated subcutaneously (s.c.) at day 0 with a total of 0.5 ml containing 10^7 IU VRP at one (strain 2) or two (strain 13) dorsal sites. Challenge was carried out 4 weeks after final immunization with VRP. Guinea pigs were challenged s.c. with 1000 LD50 of guinea pig- adapted Ebola virus. Animals were observed daily for 60 days, and morbidity (determined as changes in behavior, appearance, and weight) and survival were recorded. Blood samples were taken on the days indicated after challenge and viremia levels were determined by plaque assay (Pushko et al., 2000).
• Efficacy: At day 7 after challenge, NP-VRP-vaccinated group had lower viremia titers than control animals. All mock vaccinated animals or NP-VRP-vaccinated animals became ill, and died at days 8±11 after challenge (Pushko et al., 2000).