The average anti-human VEGF antibody titers corresponding to each blood extraction during the experiment is depicted in Fig. 7. In the weekly schedule group, all vaccinated monkeys responded with anti-VEGF-specific IgG antibodies (1:3000) following the first dose and average titers reached 1:6000 after the eighth dose of the induction phase. A reduction in antibody titer was observed in the sample taken 67 days after the eighth dose. Average titers experience a boost to 1:8000 after monthly immunization

was re-initiated on day 126. These values dropped progressively to near first dose titer 94 days after the third and last maintenance phase vaccination. click here Monkeys receiving CIGB-247 biweekly also responded producing VEGF-specific IgG antibodies following the first dose, and average titer values fluctuated between 1:2500 and 1:3800 during all the induction phase. Titers were boosted to an average of 1:5800 after the first dose of the maintenance phase and declined in a fashion similar to that seen for the weekly scheme. The addition of montanide to the biweekly scheme had two effects. Firstly, whereas average

titer values were in a similar range as those reported above, these fluctuated less during the induction phase and did not seem to drop. Secondly, titers rose over Selleck Verteporfin those produced by the biweekly immunization without montanide during maintenance phase and peaked to 1:7300, almost reaching the levels produced by the weekly scheme. Anti-VEGF antibody titer declination after the last immunization was similar to what was described already for the other two schemes. The ability of serum to block the interaction of KDR-Fc with human VEGF was estimated using the same inhibition ELISA system reported for rats and rabbits, with a change in the final detection reagents Terminal deoxynucleotidyl transferase (due to the human-like Fc of monkey antibodies). The best serum dilution for this test was 1:500. Fig. 8 depicts the average inhibition values

(three repetitions of each sample) produced by dilutions of the sera of individual monkeys of each scheme, taken after the fourth, sixth and eighth vaccinations. Sera from all the vaccinated monkeys showed some inhibition of VEGF/KDR-Fc interaction after the fourth dose, with a majority showing inhibition peaks after the sixth dose. Animals immunized under the weekly and biweekly plus montanide schedules exhibited significantly higher inhibition values than those detected after the biweekly vaccination (p < 0.05, One way ANOVA, Bonferroni post-test). IgG antibodies were purified from sera of individual monkeys from the weekly scheme at peak titer (day 189), and tested at specific IgG concentrations in the same ELISA inhibition system. Fig. 9 shows that purified antibodies have better specific inhibition activity in the test.