QUANTITATION OF CAT IMMUNOGLOBULINS IN THE HEMOLYMPH OF CAT FLEAS (SIPHONAPTERA, PULICIDAE) AFTER FEEDING ON BLOOD

Passage of ingested cat immunoglobulin G (IgG) into the hemocoel of ca t fleas, Ctenocephalides felis (Bouche), was examined using antibody c apture enzyme-linked immunosorbent assays (ELISA) and Western blotting . Fleas were fed heparinized cat blood via membrane feeders. Cat Ige w as present in the hemolymph of engorged female fleas 1 h after ingesti on at an estimated quantity of 35 +/- 14 mu g/ml. The prevalence of fl eas with demonstrable cat IgG in their hemolymph 1 h after feeding was 100% for both female and male ness. Following a single blood meal, ca t IgG was present in the hemolymph of all 15 fleas tested 1 h after in gestion but dissipated below detectable levels in 10 of 20 fleas exami ned 3 h after ingestion, and was detectable in only 1 of 10 fleas exam ined 18 h after ingestion. However, when fleas were provided with cont inual access to blood over a 72-h period. IgG content in hemolymph, as measured in excised, triturated legs of individual fleas, remained fa irly constant (3-16 pg IgG per sample). Flea feeding studies using spe cific antisera indicated that IgG in flea hemolymph retained its bindi ng activity, and that at least a portion of the IgG was intact. Passag e of ingested host antibody from gut into hemocoel is a prerequisite f or the possible development of antiflea vaccines that target antigens outside of the flea midgut lumen (e.g., key components of the nea endo crine system controlling oogenesis).