MOMP specific antibody titres. The vaccinated group was intramuscularly immunised with pcDNA1::MOMP. Budgerigars in the placebo-vaccinated group received an empty pcDNA1 plasmid (placebo). Sampling time-points: day of the primary vaccination (Prevaccination); 21 days post primary vaccination (PPV); 14 days post booster vaccination (PBV); 14 days post challenge (PC). Mann–Whitney test was used to perform statistics. Before vaccination, antibody titres were not statistically different. Antibody titres were significantly different on all other time points. The 25 and 75 percentiles are indicated using the bars. The p values for these points are indicated with asterisks as in Figure 3.