Neospora caninum surface antigen (p40) is a potential diagnostic marker for cattle neosporosis

Authors: HU, P - Jilin University; LI, J - Jilin University; GONG, P - Jilin University; LIU, C - Jilin University; ZHANG, G - Jilin University; YANG, J - Jilin University; Tuo, Wenbin; YANG, B - Jilin University; ZHANG, X - Jilin University

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2013
Publication Date: 5/1/2013
Publication URL: http://handle.nal.usda.gov/10113/586842
Citation: Hu, P., Li, J., Gong, P., Liu, C., Zhang, G., Yang, J., Tuo, W., Yang, B., Zhang, X. 2013. Neospora caninum surface antigen (p40) is a potential diagnostic marker for cattle neosporosis. Parasitology Research. 112(5):2117-2120.

Interpretive Summary: Potential markers are needed to develop sensitive and reliable diagnostic tests for neosporosis. This study cloned and expressed the N. caninum P40 antigen (NcP40) in bacterium and its potential as a diagnostic marker was determined. The results showed that NcP40 does not cross-react with antibodies of other related antigens. The NcP40-specific ELISA has a sensitivity and specificity of greater than 98%, as confirmed by the gold-standard indirect fluorescence antibody test (IFAT). This sensitive and specific test is a reliable method for the diagnosis of neosporosis in cattle. This information is useful to the cattle industry.

Technical Abstract: Neospora caninum is an intracellular protozoan that infects domestic and wild canids as well as many warm-blooded animals as shown by the isolation of viable parasites. The effectiveness of diagnostic tests for detecting specific antibodies against N. caninum is hampered by potential cross-reaction with other Coccidia. So, there is currently an urgent need for a sensitive and specific diagnostic assay for detecting N. caninum in animals. The N. caninum 40-kD surface antigen (p40), similar to NcSAG1 and NcSRS2, was shown to belong to surface antigen super family and thus represents an excellent marker for the diagnosis of neosporosis. In order to test the hypothesis, recombinant Ncp40 (rNcp40) was expressed in Escherichia coli, and an indirect ELISA test was developed using recombinant NCp40 antigen for N. caninum serodiagnosis. The antigen used in this study did not have cross-reactivity with anti-Toxoplasma gondii serum. Anti-p40 antibodies were detected by ELISA in the sera of Yellow cattle and were compared with (IFAT). Optimal sensitivity and specificity (98.2 and 98.6%) were identified by IFAT. Additionally, 37 positive sera of T. gondii were detected and there was no significant difference with the negative serum of N. caninum. The rNcp40 ELISA developed here provides a specific and sensitive assay for detecting neosporosis in cattle.