Comparison of the efficacy of replication-defective adenovirus and Nyvac poxvirus as vaccine vectors in mice

Adenovirus and poxvirus recombinant vectors are more and more used as live experimental vaccines. In order to compare the efficacy of these vectors to elicit serological response and protection against challenge, two recombinants carrying the same gene (pseudorabies virus gD) were used as experimental vaccines in mice, a permissive species to pseudorabies infection. Two routes were tested: intramuscular (i.m.) and intranasal (i.n.) in order to try to stimulate general and mucosal immune responses. Several doses ranging from 10(2.9) to 10(8.9) TCID50, depending on the vaccines were tested. The estimated log 10 (PD50) for the i.m. route were 7.1 +/- 0.2 for the adenovirus vector (Ad-gD), and 7.6 +/- 0.2 for the Nyvac vector (vP900). For the i.n. route, log 10 (PD50) of Ad-gD was 7.1 +/- 0.2, and was higher than 7.9 for vP900. While the adenovirus vector proved more efficient than the poxviral vector to elicit antibody response, only a slight difference was observed when comparing the survival times of animals after challenge. Adenovirus was found better only for the 10(7.9) TCID50 dose, when inoculated i.m. Intranasal vaccination appeared efficient only with the adenovirus vector for the TCID50 10(8.9) dose.