Extraction of Haemoproteus columbae (Haemosporina: Haemoproteidae) antigen from rock dove pigeons (Columba livia) and its use in an antibody ELISA

Erythrocytic stages of Haemoproteus columbae were extracted from the cytoplasm of nucleated red blood cells (RBC) of Rock dove pigeons (Columba livia) using cationic detergent (N,N',N'-polyoxyethylene(10)-N-tallow-1,3- diaminopropane[EDTA-20]) and discontinuous Percoll gradient density. Crude RBC extract (CRBCE) antigen was prepared. Parasitized RBCs were more resistant to EDTA-20 action than unparasitized cells. An enzyme-linked immunosorbent assay (ELISA) was developed for detection of anti-H. columbae immunoglobulins in 30 wild-captured C. livia. Whole blood, serum, and dried blood on filter paper gave similar results; the latter was selected for sampling convenience. Optimal antigen concentration was 5 μg/ml, and anti- H. columbae immunoglobulins were detectable at a 10^-4.11 dilutions. The binding efficacy of anti-chicken IgG to the pigeon immunoglobulins was significantly higher than anti-duck IgG or anti-turkey IgG. Parasitemia by Giemsa-stained thin blood smears ranged from 20.0 to 47.5%, x̄ = 32.4 ± 8.3%; 17 of 30 birds had multiply infected RBCs with a mean parasitemia of 2.4 ± 1.1%, range 0.7-4.9%; 27 birds were positive by the ELISA. No clinical signs of infection were observed. ELISA absorbance values were not correlated with the level of parasitemia in individual birds. All pigeons were negative for anti-Plasmodium relictum and anti-P. elongatum immunoglobulins as determined by ELISA. The pigeons were not subclinically infected with Plasmodium spp. as determined by inoculation of domestic ducklings with blood from dexamethasone-immunosuppressed pigeons.