Detection of false-positive sera in contagious agalactia with a multiantigen ELISA and their elimination with a protein G conjugate

CNEVA Sophia Antipolis, Unite Pathologie des Petits Ruminants, France.

In serology, lack of specificity can generally be attributed to cross-reactions between different pathogens with antigens bearing similar epitopes. During seroepidemiologic surveys of contagious agalactia of sheep caused by Mycoplasma agalactiae infection, numerous sera were analyzed by enzyme-linked immunosorbent assay (ELISA). A few sera reacted with various antigens coated on plates, including the well with no antigen. This reactivity was not due to cross-reactions as initially suspected, and these multipositive sera were designated false-positive sera. Elimination of this false positivity was not possible by using covalent ELISA plates or different rabbit anti-sheep IgG conjugates. Only conjugates using monoclonal antibodies or protein G were efficient in elimination of false positivities without reducing the true specific positive titers. No false-positive sera have been observed since the implementation of protein G conjugates in the serologic diagnosis of contagious agalactia by ELISA for the past 2 years.

This article has been cited by other articles:

				B. Fleury, D. Bergonier, X. Berthelot, Y. Schlatter, J. Frey, and E. M. Vilei Characterization and Analysis of a Stable Serotype-Associated Membrane Protein (P30) of Mycoplasma agalactiae J. Clin. Microbiol., August 1, 2001; 39(8): 2814 - 2822. [Abstract] [Full Text] [PDF]