SENSITIVE AND SPECIFIC IDENTIFICATION OF NEOSPORA CANINUM INFECTION OF CATTLE BASED ON DETECTION OF SERUM ANTIBODIES TO RECOMBINANT NCP29

Authors: HOWE, DANIEL - WASH. UNIV. SCH. OF MED.; TANG, KELIANG - WASH. UNIV. SCH. OF. MED; CONRAD, PATRICIA - UNIV. OF CALIFORNIA; SVERLOW, KAREN - UNIV. OF CALIFORNIA; Dubey, Jitender; SIBLEY, L - WASH. UNIV. SCH. OF MED.

Submitted to: Clinical and Diagnostic Laboratory Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2002
Publication Date: 7/2/2002
Citation: Howe, D.K., Tang, K., Conrad, P.A., Sverlow, K., Dubey, J.P., Sibley, L.D. 2002. Sensitive and specific identification of neospora caninum infection of cattle based on detection of serum antibodies to recombinant ncp29. Clinical and Diagnostic Laboratory Immunology 9:611-615.

Interpretive Summary: Neospora caninum is a single-celled parasite. It causes abortion in livestock and paralysis in companion animals. Diagnosis of abortion in diary cattle due to neosporosis is a major problem. Scientists at the Beltsville Agricultural Research Center and the Washington University School of Medicine have developed a sensitive and specific ELISA test using a recombinant protein from N. caninum. These results will be of interest to parasitologists, molecular biologists and veterinarians.

Technical Abstract: Neosporosis is an economically important disease of diary cattle caused by the protozoan Neospora caninum. Diagnostic tests for neosporosis are complicated by the potential for cross reaction of antibodies to antigens that are similar between N. caninum and the closely related parasites Toxoplasma gondii and Sarcocystis cruzi. To provide a sensitive and specific assay for detecting antibodies to N. caninum in the serum of infected animals, we have investigated a recombinant form of the antigen known as Ncp29 (rNcp29), which is a major surface protein of the parasite. Ncp29 is encoded by a gene that is homologous to the SAG1 gene previously characterized from T. gondii. An enzyme-linked immunosorbant assay (ELISA) was used to screen animals for the presence of serum antibodies specific to rNcp29. The rNcp29 ELISA readily distinguished between cattle known to be infected with N. caninum (optical density (O.D.) >1.2 at 1:500 or greater dilution) and negative controls (O.D. <0.5 at 1:500). Additionally, sera from animals that were infected with T. gondii or S. cruzi were negative. The rNcp29 ELISA developed here provides a specific and sensitive assay for detecting neosporosis in cattle.