An inactivated poliovirus vaccine using Sabin strains produced on the serum-free PER.C6® cell culture platform is immunogenic and safe in a non-human primate model

Figures

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  Fig. 1. Immunogenicity of monovalent and trivalent PER.C6®-based Sabin IPV (sIPV) for Sabin poliovirus type 1, 2 and 3 compared to the reference standard BRP2 in the Wistar rat model. Sabin virus neutralizing titers were determined three weeks following vaccination of Wistar rats with four serial dilutions of PER.C6®-based monovalent and trivalent sIPV or four serial dilutions of reference standard BRP2. Starting dose for the monovalent sIPV vaccines was 7 DU/dose, 85 DU/dose and 85 DU/dose for type 1, 2 and 3 respectively. The starting dose of the PER.C6®-based trivalent sIPV was 5/62/65 DU/dose). Representative results of one out of two independent experiments are shown in the graphs. Dots show results from individual animals. Dotted lines show the lower limit of quantification. Horizontal lines show geometric means. The relative potency of the monovalent and trivalent PER.C6®-based sIPV product compared to the reference standard BRP2 is indicated in the table below, where a vaccine was considered to be comparable to the reference if the upper limit of the 95% confidence interval (CI) of the relative potency estimate was >1.0.

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  Fig. 2. Immunogenicity and relative potency of a trivalent PER.C6®-based Sabin IPV (sIPV) as measured by Sabin neutralizing antibody titers relative to the reference standard BRP2 in the Wistar rat model. Wistar rats were intramuscularly immunized with four serial dilutions of PER.C6®-based sIPV (starting dose 10-15-50 DU/dose) or reference standard BRP2 (starting dose 40-8-32 DU/dose). Three weeks after immunization, sera were collected and analyzed with a Sabin neutralizing antibody assay. Virus neutralizing antibody titers are shown for each animal at each dilution (dots represent individual animals) and the dotted line represents the assay start dilution. The relative potency of the trivalent PER.C6®-based sIPV product compared to the reference standard BRP2 is indicated in the table below, where a vaccine was considered to be comparable to the reference if the upper limit of the 95% confidence interval (CI) of the relative potency estimate was >1.0.

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  Fig. 3. Sabin virus neutralizing antibody titers against poliovirus type 1, 2 and 3, three weeks after the third immunization in cynomolgus monkeys immunized with different polio vaccines. Cynomolgus monkeys (6 per group) were intramuscularly immunized with PER.C6®-based Sabin IPV (sIPV), or a reference Salk IPV (ref cIPV, Imovax, Sanofi) or a reference sIPV (ref sIPV, Kunming). For both commercial vaccines, one full human dose was used, and for the PER.C6®-based sIPV four different D-antigen unit dose formulations were tested, annotated as H, M, M-L and L. The different dose formulations represent: H = high dose formulation (20-30-100 DU), M = mid dose (10-15-50 DU), M-L = mid low dose (5-7.5-25 DU), L- low dose (2.5-3.75-12.5 DU). Three weeks after the third immunization sera were collected and analyzed with Sabin virus neutralizing antibody assays. The titration endpoint per animal is presented as a reciprocal of the titer. Dots represent individual animals. Horizontal lines show geometric means. The dotted line is the cut-off for seroprotection in humans (serum dilution of 1:8).

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  Fig. 4. Non-inferiority of PER.C6®-based sIPV compared to Sabin IPV (sIPV) and Salk IPV (cIPV) commercial reference vaccines based on Sabin virus neutralizing antibody titers after three immunizations (at week 9). Sera from cynomolgus monkeys, immunized 3 times with one of the four dose formulations of PER.C6®-based sIPV or commercial cIPV or sIPV, were analyzed with Sabin viral neutralizing assay to determine Sabin virus neutralizing antibody titers. The four different D-antigen unit dose formulations were high dose formulation (20-30-100 DU), mid dose (10-15-50 DU), mid low dose (5-7.5-25 DU) and low dose (2.5-3.75-12.5 DU). To assess non-inferiority between the different vaccines, an area under the curve analysis at week 9 was performed. A vaccine formulation is regarded non-inferior compared to the reference vaccine if the lower limit of the 95% confidence interval (CI) of the difference in log10 titer is above −0.6 difference in log10 titer (indicated by the vertical dotted line).

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  Fig. 5. Salk virus neutralizing antibody titers against poliovirus type 1, 2 and 3, three weeks after the third immunization in cynomolgus monkeys immunized with different polio vaccines. Cynomolgus monkeys (6 per group) were intramuscularly immunized with PER.C6®-based sIPV, or a reference Salk IPV (ref cIPV, Imovax, Sanofi) or a reference Sabin IPV (ref sIPV, Kunming). For both commercial vaccines, one full human dose was used, and for the PER.C6®-based sIPV four different D-antigen unit dose formulations were tested, annotated as H, M, M-L and L. The different dose formulations represent: H = high dose formulation (20-30-100 DU), M = mid dose (10-15-50 DU), M-L = mid low dose (5-7.5-25 DU), L-low dose (2.5-3.75-12.5 DU). Three weeks after the third immunization sera were collected and analyzed with Salk virus neutralizing antibody assays. The titration endpoint per animal is presented as a reciprocal of the titer. Dots represent individual animals. Horizontal lines show geometric means. The dotted line is the cut-off for seroprotection in humans (serum dilution of 1:8).

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  Fig. 6. Kinetics of the immune response for the mid-low dose of PER.C6®-based Sabin IPV (sIPV) and commercial reference Salk IPV (cIPV) and sIPV up to week 20 after vaccination. Cynomolgus monkeys were immunized at week 0, 3, 6 and 17 with the indicated vaccines. Sera were collected and virus neutralizing antibody titers for Sabin were measured prior to each immunization and at week 9 and 20 after start of the study. The mean (+/− SD) titration endpoint per group (n = 6) is presented as a reciprocal of the titer. The dotted line is the cut-off for seroprotection in humans (serum dilution of 1:8). Footnote: reference cIPV = Imovax, Sanofi; reference sIPV = commercial sIPV, Kunming.

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  Fig. 7. Kinetics of the immune response for the mid-low dose of PER.C6®-based Sabin IPV (sIPV) and commercial reference Salk IPV (cIPV) and sIPV up to week 20 after vaccination. Cynomolgus monkeys were immunized at week 0, 3, 6 and 17 with the indicated vaccines. Sera were collected and virus neutralizing antibody titers for Salk were measured prior to each immunization and at week 9 and 20 after start of the study. The mean (+/− SD) titration endpoint per group (n = 6) is presented as a reciprocal of the titer. The dotted line is the cut-off for seroprotection in humans (serum dilution of 1:8). Footnote: reference cIPV = Imovax, Sanofi; reference sIPV = commercial sIPV, Kunming.