Immunospecific Antibody Concentration in Egg Yolk of Chickens Orally Immunised with Varying Doses of Bovine Serum Albumin and the Mucosal Adjuvant, RhinoVax®, using Different Immunization Regimes
Antibody harvested from eggs of immunised chickens, IgY, has proven to be a non-invasive alternative to antibodies purified from serum of mammals. Taking the non-invasive concept further, the development of oral immunization techniques combined with IgY harvest from chicken eggs may subsequently eliminate all regulated procedures from polyclonal antibody production. In the present study, we report the effects of varying the temporal administration mode of the antigen (immunogen) comparing dosing on three consecutive days with dosing on five consecutive days, and of incorporating a mucosal adjuvant. Two antigen doses were compared: 30 mg bovine serum albumin (BSA) and 300 mg BSA, with and without the mucosal adjuvant, RhinoVax®, administered to laying chickens. The egg yolk of chickens dosed with BSA in combination with 20% RhinoVax®, contained significantly higher concentrations of immunospecific IgY than did egg yolks of chickens fed with BSA without adjuvant. The most efficient dose in the RhinoVax®-treated groups was 300 mg BSA regardless of whether the chickens were initially immunised daily for three or five days. A 3-day dosing regime with BSA alone also induced immunospecific IgY production. This study confirms that RhinoVax® is an efficient oral adjuvant. It also demonstrates the efficacy of daily immunizations on three or five consecutive days on immunospecific IgY production. The chickens received oral booster immunizations one and two months after the initial immunization. No real effect could be recorded after the second and third immunization, although the study did provide some evidence of memory based on an optimum IgY concentration recorded after the 2nd immunization.