A Multiple Dose Immunisation Protocol Suitable For Edible Vaccines

Abstract

Frequent administration of oral immunisation has proven to be more successful than single administration. The frequency of feeding edible vaccines, however, is limited by the maximal oral intake, the lack of nutritional value and the possible presence of toxic ingredients. Therefore, we designed a protocol in which the animals received multiple immunisations on three alternating days ('triple dose') and the protocol was compared to single immunisations. Mice were immunised via intragastric (IG) gavage with ovalbumin (OVA) mixed with cholera toxin (CT) and the effects on systemical and local immune responses were determined. Serum IgG1 and IgA titres against OVA after oral boost immunisation given three weeks after primary immunisation were significantly higher after 'triple dose' than after 'single dose' immunisation. Faecal IgA was detected only after 'triple dose' boost immunisation. A second boost did not further increase serum IgG1 and faecal IgA. Antibody responses against CT were also elicited and again, boost immunisations did not further increase this response. We concluded that oral immunisation with multiple doses was more effective than 'single dose' immunisation and it seems practical and efficient for edible vaccines.