Systemic immune response of young chickens orally immunized with bovine serum albumin.

The efficacy of oral immunization, with and without commercial adjuvants, to mount a systemic immune response in young chickens was studied. Bovine serum albumin (BSA) mixed with a pegylated C8/C10 mono/di-glyceride, (Softigen), or Cholera toxin B-subunit (CTB), administered orally by gavage to 15-day-old chickens resulted in circulating immunospecific anti-BSA IgG, IgM and IgA antibodies. Continuous 5-day oral administration of BSA without adjuvant also resulted in immunospecific IgM and IgA antibodies in the circulation of chickens first immunized at 15 days of age; and immunospecific antibodies of all three classes in chickens first immunized when they were 22 days old. IgG and IgM serum concentrations were more than 4 to 10 times higher, respectively, in CTB- and Softigen-treated chickens as compared to chickens immunized without adjuvants. The IgA response in the orally immunized chickens seemed unaffected by CTB and Softigen. The antibody concentrations in chickens immunized subcutaneously with BSA emulsified in Freund's Incomplete Adjuvant (FIA) were approximately 10 times higher than those of the chickens orally immunized using CTB and Softigen.