Solidarity/Tokomeza Ebola Trial

Incidence of solicited, unsolicited adverse and serious adverse events (safety)

The adverse events (AE) and serious adverse events (SAE) will be evaluated to determine the link to the investigational product. They will then be classified as possibly, probably and definitely related to the investigational products

Vaccine-specific antibody concentration (immunogenicity) measured as optical density that will be converted to concentration

The vaccine specific antibody concentration will be assessed through specific laboratory procedures that make use of Nunc Maxisorp flat bottom plates will be coated with Ebola GP in a coating buffer. Heat inactivated serum or plasma from study participants (either diluted and or undiluted) or treated plasma sample from SUDV convalescent individuals (Positive control) or Mouse anti SUDV GP mAb (positive control) will be added to the plates and incubated. The plates will be washed and HRP goat anti-human IgG antibody and or HRP goat anti-human IgM antibody and or HRP goat anti-mouse IgG Fc or HRP goat anti-mouse IgM Fc will be added. The plates will be washed and tetramethylbenzidine (TMB) 1 component microwell peroxidase substrate added. The reaction will be stopped after about 20 minutes with hydrochloric acid. The plate's absorbance will be read at 450 nm and 630 nm. A standard curve/line will be drawn and convert the optical density to concentration

Vaccine specific antibody neutralization capability (immunogenicity) represented as proportion of neutralization

Vero cells will be incubated in Eagles Minimum Essential Medium with fetal bovine serum and penicillin/streptomycin (R10) and maintained at 37°C and 5% CO2 humidified incubator. The cells will be plated onto a 96 well black flat bottomed culture plate. Study participant, positive (obtained from SUDV convalescent individuals and pre-treated) and negative controls heat inactivated serum samples will be diluted and mixed with single round infecting recombinant vesicular stomatitis virus expressing SUDV GP and firefly luciferase at room temperature with appropriate controls. The virus and serum sample mixture will be added to the plated vero cells and incubated for up to 24 hours. The virus and serum sample will be removed and vero cells lysed. Luciferase activating reagent will be added and the luminescence will be read using a luminescence plate reader. The proportion of neutralisation will be evaluated using appropriate controls (rVSV without serum).

Vaccine-induced T cell responses (immunogenicity) determined as spot forming units per one million cells.

This will be done as per the standard operating procedures. IFN-γ precoated ELISPOT plates will be washed and blocked using serum. Thawed and rested PBMC will be plated, stimuli (peptides to ebola GP, appropriate positive and negative controls) added and incubated for 12 to 24 hours. The plates will be emptied and washed after incubation. Diluted enzyme-conjugate detection IFN-γ antibody will be added and incubated. The plates will be washed \& substrate added and allowed to develop for about 20 minutes. The development will be stopped by rinsing the plates in copious amounts of deionised water. The plates will be allowed to air dry in the dark and read using an ELISPOT reader within 12 hours. The results will be determined as spot forming units per one million cells

Durability of the immune response measured up to 72 months quantitively by assessing the antibody concentration and qualitatively by assessing the antibody neutralization capacity. Curves will be drawn to represent immune responses against time

Blood samples will be collected at different time points and the immunogenicity assays repeated. Curves will then be drawn to represent how the antibody titers against time