An enzyme-linked immunosorbent assay (ELISA) for serological diagnosis of Neospora sp. infection in cattle

Julie Paré, Mark Thurmond

Research output: Contribution to journalArticlepeer-review

154 Scopus citations


A kinetic enzyme-linked immunosorbent assay (ELISA) was developed and optimized for detection of antibodies to Neospora sp. in cattle. Sonicated tachyzoites of Neospora sp. isolated from an aborted bovine fetus were used as antigen. Variability in immunoblot patterns among positive sera, and the fact that all life stages of the parasites are unknown, justified use of a multiple-antigen ELISA to allow for maximum sensitivity. Immunoblot analysis revealed negligible cross-reactions between Toxoplasma gondii antigen and Neospora sp. antisera and between Neospora sp. antigen and antisera from various apicomplexan parasites. The maximum positive-to-negative Vmax(average maximum slope of the optical density over time) ratio was obtained using 200 ng/well of sonicated tachyzoite antigen and a 1:200 serum dilution. Using logistic regression to determine the optimal cutoff point between known infected and noninfected cattle, a sample-to-positive control Vmaxratio of 0. 45 was found to maximize the percent correct classification, with an estimated sensitivity of 88. 6% and specificity of 96. 5%. Use of Neospora caninum antigen following the same protocol demonstrated no difference in ELISA interpretation. Comparison with an existing indirect immunofluorescent antibody (IFA) test showed the ELISA to be the more sensitive and specific test for serodiagnosis of Neospora infection in cattle.

Original languageEnglish (US)
Pages (from-to)352-359
Number of pages8
JournalJournal of Veterinary Diagnostic Investigation
Issue number3
StatePublished - Jan 1 1995

ASJC Scopus subject areas

  • veterinary(all)


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