Generation of transgenic corn-derived Actinobacillus pleuropneumoniae ApxIIA fused with the cholera toxin B subunit as a vaccine candidate

Abstract

Corn, one of the most important forage crops worldwide, has proven to be a useful expression vehicle due to the availability of established transformation procedures for this well-studied plant. The exotoxin Apx, a major virulence factor, is recognized as a common antigen of Actinobacillus (A.) pleuropneumoniae, the causative agent of porcine pleuropneumonia. In this study, a cholera toxin B (CTB)-ApxIIA#5 fusion protein and full-size ApxIIA expressed in corn seed, as a subunit vaccine candidate, were observed to induce Apx-specific immune responses in mice. These results suggest that transgenic corn-derived ApxIIA and CTB-ApxIIA#5 proteins are potential vaccine candidates against A. pleuropneumoniae infection.

Fig. 1

ApxII-specific IgG (A) and IgA (B) levels 2 weeks after final boosting (^**p < 0.01). CTB: cholera toxin B.

Fig. 2

ApxII-specific memory B cells producing IgG (A) and IgA (B) in mice immunized with corn-derived ApxIIA (█: untreated control, ▒: ApxIIA, □: lipopolysaccharides; ^*p < 0.05, ^**p < 0.01).

Fig. 3

Secretion of interferon-γ (A) and nitric oxide (B) from murine splenocytes stimulated with ApxIIA and ConA, or the untreated control (█: administration of cholera toxin B-ApxIIA#5, □: administration of full ApxIIA; ^*p < 0.05, ^**p < 0.01).