Immunology of Edible Vaccines and its Veterinary Importance

The greatest numbers of immune cells are associated with the gastrointestinal tract. At least 80% of all plasma cells are found in the intestinal lamina propria, and together they produce more IgA than all other immunoglobulin isotypes combined. IgA is found in enormous amounts in saliva, intestinal fluid, nasal, and tracheal secretions, tears, milk, colostrum, urine, and the secretions of the urogenital tract. When animals are vaccinated against organisms that invade the intestinal or respiratory tracts, it makes sense to stimulate a mucosal IgA response