Percent colonization of mice which orally received PBS (•), LT R192G (▪), or GST-PorA + LT (○). Each group of mice (n = 9) was challenged with the homologous strain C. jejuni C31 (O:6,7) (A) or the heterologous strains C. jejuni 48 (O:19) (B), C. jejuni 75 (O:3) (C), and C. jejuni 111 (O:1,44) (D).