A modified agglutination test for Neospora caninum: Development, optimization, and comparison to the indirect fluorescent-antibody test and enzyme-linked immunosorbent assay

Andrea E. Packham, Karen W. Sverlow, Patricia A Conrad, Emily F. Loomis, Joan D Rowe, Mark L Anderson, Antoinette E. Marsh, Carolyn Cray, Bradd C. Barr

Research output: Contribution to journalArticle

93 Scopus citations


Current serologic tests used to detect antibodies to Neospora caninum require species-specific secondary antibodies, limiting the number of species that can be tested. In order to examine a wide variety of animal species that may be infected with N. caninum, a modified direct agglutination test (N-MAT) similar to the Toxoplasma gondii modified direct agglutination test (T-MAT) was developed. This test measures the direct agglutination of parasites by N. caninum-specific antibodies in serum, thus eliminating the need for secondary host-specific anti-isotype sera. The N-MAT was compared to the indirect fluorescent-antibody test (IFAT) and the enzyme-linked immunosorbent assay (ELISA) with a 'gold standard' serum panel from species for which secondary antibodies were available (n = 547). All positive samples tested were from animals with histologically confirmed infections. Up to 16 different species were tested. The N-MAT gave a higher sensitivity (100%) and specificity (97%) than the ELISA (74 and 94%, respectively) and had a higher sensitivity but a lower specificity than the IFAT (98 and 99%, respectively). The reduced specificity of the N-MAT was due to false-positive reactions in testing fetal fluids with particulate matter or severely homolyzed serum. Overall, the N-MAT proved to be highly sensitive and specific for both naturally and experimentally infected animals, highly reproducible between and within readers, easy to use on large sample sizes without requiring special equipment, and useful in testing serum from any species without modification.

Original languageEnglish (US)
Pages (from-to)467-473
Number of pages7
JournalClinical and Diagnostic Laboratory Immunology
Issue number4
StatePublished - 1998


ASJC Scopus subject areas

  • Microbiology (medical)
  • Immunology and Allergy
  • Clinical Biochemistry
  • Immunology

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