Antigen sparing with adjuvanted inactivated polio vaccine based on Sabin strains

Abstract

Six different adjuvants, each in combination with inactivated polio vaccine (IPV) produced with attenuated Sabin strains (sIPV), were evaluated for their ability to enhance virus neutralizing antibody titres (VNTs) in the rat potency model. The increase of VNTs was on average 3-, 15-, 24-fold with adjuvants after one immunization (serotypes 1, 2, and 3, respectively). Also after a boost immunization the VNTs of adjuvanted sIPV were on average another 7-20-27 times higher than after two inoculations of sIPV without adjuvant. The results indicate that it is feasible to increase the potency of inactivated polio vaccines by using adjuvants.

Fig. 1

(wt polio)Virus neutralizing antibody titers from rats (n=10/group) 21 days after one immunization with various doses of inactivated Sabin polio vaccine (with or without aluminium hydroxide) type 1 (A), type 2 (B), and type 3 (C), respectively. Each symbol represents the titer of one individual rat and means are indicated by horizontal bars. Sera that were positive at the highest dilution (1:4096), i.e. titer is equal or larger than 13 are represented as 13(log₂); sera that were negative at the 1:2 dilution are designated as 1. Statistical significance to sIPV was determined by the Mann-Whitney two-tailed test using GraphPad Prism version 5. *P <0.05, **P <0.01.

Fig. 2

(wt polio)Virus neutralization antibody titers from rats (n=15/group) 21 days following a prime (A) and boost (B) immunization (day 28) with 0.4–0.6–1.2 DU/rat for sIPV type 1, 2 and 3 (with or without EM030), respectively. Each symbol represents the titer of one individual rat and means are indicated by horizontal bars. Sera that were negative at the 1:2 dilution are designated as 1. Statistical significance to sIPV was determined by the Mann-Whitney two-tailed test using GraphPad Prism version 5. *P <0.05, **P <0.01, ***P<0.001.

Fig. 3

(wt polio)Virus neutralization antibody titers against poliovirus type 1 (A, B), type 2(C, D) or type 3 (E, F) from rats (n=14/group) 21 days following a prime (A, C, E) and boost (B, D, F) immunization (day 28) with 0.4–0.6–1.2 DU/rat sIPV type 1, 2 and 3 respectively (with or without adjuvant). Each symbol represents the titer of one individual rat and means are indicated by horizontal bars. Sera that were negative at the 1:2 dilution are designated as 1. Statistical significance to sIPV was determined by the Mann-Whitney two-tailed test using GraphPad Prism version 5. *P <0.05, **P <0.01, ***P<0.001, ****P<0.0001.

Fig. 4

(wt polio)Virus neutralization antibody titers against poliovirus type 1, type 2 or type 3 from rats (n=14/group) 21 days following a prime (A) and boost (B) immunization (day 28) with 0.4-0.6-1.2 DU/rat sIPV type 1, 2 and 3 respectively (with or without GVI3000). Each symbol represents an individual titer and the line indicates the group mean. Statistical significance relative to plain sIPV was determined by the Mann-Whitney two-tailed test using GraphPad Prism version 5. *P <0.05, **P <0.01, ***P<0.001.