Figure 1. Pre-Existing Immunity Against Adenovirus Does not Compromise the Strength of the Cellular and Humoral Immune Response Against Ebola Glycoprotein After Intranasal Immunization.

Naïve mice (n = 10) were vaccinated with a single dose of 1×10¹⁰ particles of adenovirus expressing the Ebola Zaire glycoprotein (Ad5-ZGP) by the intramuscular (I.M.), nasal (I.N.) or oral (P.O.) route. Animals in which pre-existing immunity (PEI) was established by I.M. injection of 5×10¹⁰ particles of adenovirus serotype 5 expressing beta-galactosidase (AdlacZ) 30 days prior to vaccination were also immunized in the same manner. At the time of vaccination, mice had an average anti-adenovirus circulating NAB titer of 1∶320. Animals given a single dose of (AdlacZ) served as negative controls (AdlacZ Control). (A) Frequency analysis of IFN-γ secreting CD8+ T cells harvested from splenocytes 10 days post-immunization (n = 4/group). The TELRTFSI peptide, specific for the Ebola Zaire glycoprotein (0.4 µg/well), was incubated with 1×10⁶ splenocytes and cells analyzed by flow cytometry. (B) Neutralizing antibody (NAB) levels against ZEBOV-EGFP were evaluated 25 days post-vaccination (n = 10/group). In both panels, error bars represent the standard deviation of the data.