Table 2. At the end of the experiment, pharyngeal excretion in the control group was significantly higher than in the vaccinated groups. When evaluating pharyngeal excretion, best protection seemed to occur for group 2 as bacterial excretion was no longer observed from day 17 PC until euthanasia. All other groups were still excreting living Cp. psittaci via the pharynx until the end of the experiment. In group 2, 100% of the animals remained positive until 11 days PC, while bacteria were still present in the pharynx of all turkeys (100%) of groups 1 and 3 at 23 and 21 days PC, respectively. Thus, regarding pharyngeal chlamydial shedding,

the best protection seemed to occur for the polyplex IM group and protection for the plasmid IM group and the polyplex

AE group was comparable. In general, cloacal shedding in the control 3-Methyladenine chemical structure DAPT research buy animals was higher than in the vaccinated groups. Cp. psittaci shedding is known to occur intermittently and statistics revealed no differences for cloacal shedding between the vaccinated groups. However, based on the results in Suppl. Table 2B, best protection seemed to occur for groups 2 and 3 as faecal excretion in all turkeys (100%) was only observed until 13 days PC, while cloacal shedding in all turkeys (100%) of group 1 was again observed at 23 days PC. Three weeks following priming, total IgG (H + L) MOMP specific serum antibodies were still absent (data not shown). One and a half week following booster immunisation (4.5 weeks of age), MOMP-specific serum antibodies were present in one out of four (25%) turkeys of group 2, and

in one out of six (17%) turkeys of group 3 (Table 3). At that time, antibodies were still absent in animals of group 1. Two and a half weeks post-booster immunisation (5.5 weeks of age), three out of four (75%) animals of group 1 and all animals (100%) of groups 2 and 3 had MOMP-specific serum antibodies. These observations suggest superior immunisation of the polyplex groups. At that time, mean serum antibody titres were highest for groups 2 and 3 group, but statistics revealed no significant differences many between the vaccinated groups. In general, antibody responses, as determined in an ELISA with homologous rMOMP, were weak. Animals were challenged at 5.5 weeks of age and subsequently, all turkeys of the control group showed a primary immune response upon infection. Two weeks PC (7.5 weeks of age), the mean MOMP-specific serum antibody titre of group 2 had increased 4-fold, indicative for a secondary immune response upon challenge. At that time, the mean MOMP-specific serum antibody titres of groups 1 and 3 had increased only 1.7 and 1.3 times, respectively. Three and a half weeks PC (9 weeks of age), the mean MOMP-specific serum antibody titre of group 2 had increased further, although only 2.7-fold, whereas for groups 1 and 3, mean serum antibody titres increased 6.9 and 4.2 times.