The B cell response against Ebola glycoprotein achieved by administration of the vaccine was determined by incubating a recombinant Ebola virus (Zaire strain) expressing green fluorescent protein (ZEBOV-EGFP) with serum collected 25 days after vaccination [8, 37] . Neutralizing antibody (NAB) levels equivalent to 40610 reciprocal dilution were detected in both naïve animals and those with pre-existing immunity after intranasal immunization ( Figure 1B) . Samples from naïve animals immunized by the oral route contained NAB levels equivalent to 2065 reciprocal dilution whereas anti-Ebola NAB could not be detected in samples obtained from animals immunized by the same route with preexisting immunity (P.O.+PEI). NAB levels of 80610 were detected in samples obtained from naïve mice immunized by the intramuscular route. Anti-Ebola NAB could not be detected in samples from mice given the AdlacZ vector alone (AdlacZ Control).