Abstract: The cellular binding proteins present in membranes of fleas, especially those which are present in the digestive tract, are useful as screening tools for systemic anti-flea reagents and in the design of vaccine formulations. Particularly useful is the .alpha.-subunit of (Na.sup.+ /K.sup.+)ATPase. The .alpha.-subunit of this protein expressed in recombinant host cells in the presence of the .beta.-subunit is distributed on the membrane and the recombinant cells can thus be used to screen candidates for ability to bind the cells. Secondary screens are used to determine the specificity of the candidate reagent for flea protein as compared to a corresponding protein derived from other sources.

Abstract: A vaccine for protecting avian and mammalian subjects against flea infestation comprises the supernatant fraction of flea midgut, or the antigenic components thereof. This also has the effect of reducing flea populations in the environment of the subject. Antibodies raised by these vaccines are also useful in purification and diagnosis.

Abstract: Antigenic parasites are encapsulated in semipermeable polymeric envelope membranes to prepare implant capsules for immunizing an animal against parasitic infection. An animal may be immunized against parasitic infection by implanting into the animal the implant capsule at a location in the animal sufficient to stimulate a protective immune response in the animal to the parasite antigen.