ELISA METHOD FOR DETECTING ANTI-PLASMODIUM RELICTUM AND ANTI-PLASMODIUM ELONGATUM ANTIBODY IN INFECTED DUCKLING SERA USING PLASMODIUM-FALCIPARUM ANTIGENS

An enzyme-linked immunosorbent assay (ELISA) with 3 Plasmodium falcipa rum NF-54 antigens, R32tet(32), P.F.R27, and crude red blood cell extr act (CRBCE), was tested for detection of anti-Plasmodium relictum and anti-Plasmodium elongatum antibodies in sera from experimentally infec ted ducklings. Whole blood, serum, and dried blood on Biter paper gave similar results. The latter was selected for convenience. All birds i nfected by experimental blood challenge, but not exposed to sporozoite s, had detectable antibody (up to 1.0x10(-3.8) dilution) reactive with R32tet(32), P.F.R27, and CRBCE antigens. Ducklings infected with P. e longatum had higher antibody levels than those infected with P. relict um. In a blind trial, the described ELISA accurately distinguished ser a taken from infected and uninfected ducklings. This study provides th e first evidence on cross reactivity in the ELISA format between P. fa lciparum antigens and antibodies induced by P. relictum and P. elongat um in experimentally infected ducklings. The proposed ELISA is fast, e asy to perform, reproducible, and requires a minimal amount of equipme nt. The assay can be used for the detection of P. relictum and P. elon gatum antibodies in captive or wild ducks, along with monitoring the l evel of antibody in selected groups of birds or for surveys of laborat ory experiments where evidence of infection is required.