*2.6. Immunization of Experimental Animals Ethics Statement*

When immunizing, we used 5–6-week-old BALB/c mice (female) of weight 16–18 g from the State Research Center of Virology and Biotechnology Vector vivarium. Animals were divided into four groups with 5–10 mice in each group including (1) pE-CTL+pE-Th—mice immunized with a mix of DNA-vaccine pEV.CTL and pEV.Th encoding CTL- and Th-epitopes of Ebola virus, respectively; (2) pE-CTL—mice immunized with DNA plasmid pEV.CTL encoding CTL-epitopes of Ebola virus; (3) pDNA3.1—mice immunized with vector plasmid pDNA3.1 (negative control); and (4)—intact non-immunized animals to whom phosphate buffered saline was inoculated (PBS) (pH 7.6) (negative control). Mice were immunized three times intramuscularly with 100 μg DNA vaccine pEV.CTL or pEV.CTL + pEV.Th at 2-week intervals. An equivalent dose of pcDNA3.1 vector plasmid was used for mice from the control group. Two weeks after the last immunization, spleens were removed in animals and splenocytes were isolated to analyze T-cell immune response.
