Two weeks after the second immunization, pigs were given a third immunization with recombinant proteins prepared as MBP fusions. Pigs in the control group received GST in the first two immunizations and MBP

in the third, all in the presence of 1 mg Quil A. Blood samples were obtained from the jugular vein of all animals at weekly intervals from the first immunization until thirteen weeks later using 10 ml vacutainers (Becton Dickinson, U.K.) and 18 gauge needles. Serum was separated by centrifugation and stored at −20 °C. Pigs were challenged with T. solium eggs within a single gravid proglottid as described in [5] two weeks after the third immunization and necropsied approximately 3 months after the last immunization. Four different worms were used for supply of the gravid proglottids. The segments from selleck chemical the four worms were randomly distributed to pigs in the various experimental groups. Carcass muscle was examined for the presence of cysticerci from the challenge infection by slicing at approximately 3 mm intervals. In carcasses which were heavily infected with cysticerci, the total number in muscle were estimated by selecting a muscle sample (of known weight) from the carcass, determining the number of cysticerci in that sample and estimating the total number in the remaining muscle using

its weight. The Mann–Whitney U test was used for comparison of the number of T. solium cysticerci found in pigs in different groups immunized with the various antigens. A two-tailed P value <0.01 was Caspase inhibitor considered to be statistically significant. Specific antibody levels against TSOL16,

TSOL45-1A or TSOL45-1B were determined using an enzyme-linked immunosorbent assay (ELISA) as described in [17]. The level of antibody to the specific parasite antigens rather than to the affinity tag (GST) was measured by coating ELISA plates with parasite antigen fused to MBP. Binding of porcine antibody to the MBP fusion proteins of the recombinant antigens was detected using anti porcine IgG-horse radish peroxidase conjugate (Serotec). Antibody titres were calculated from the highest serum dilution at which the optical next density at 450 nm equalled 1.0. Antigenic cross-reactivity was investigated by direct ELISA and inhibition ELISA as detailed by Assana et al. [18]. Briefly, direct ELISA utilized TSOL18-MBP for coating the ELISA wells and application of anti-TSOL16 serum for investigations into antigenic relatedness. The ability of the heterologous recombinant proteins (TSOL18, TSOL45-1A) to inhibit binding of anti-TSOL16 antibodies to homologous antigen (TSOL16) was investigated by antibody inhibition ELISA. Inhibitory antigens were premixed with antibody prior to the addition of the mixture to antigen coated wells. The number of T. solium cysticerci detected in each pig is shown in Table 1.