Detection of false-positive sera in contagious agalactia with a multiantigen ELISA and their elimination with a protein G conjugate.
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.
Lambert
M
M
CNEVA Sophia Antipolis, Unité Pathologie des Petits Ruminants, France.
Calamel
M
M
Dufour
P
P
Cabasse
E
E
Vitu
C
C
Pépin
V
V
D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D000939:Epitopes; D005189:False Positive Reactions; D005260:Female; D007775:Lactation Disorders / Q000382:microbiology / Q000662:veterinary*; D009174:Mycoplasma / Q000276:immunology*; D009175:Mycoplasma Infections / Q000175:diagnosis / Q000662:veterinary*; D011817:Rabbits; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D012756:Sheep; D012757:Sheep Diseases / Q000175:diagnosis*
D000942:Antigens, Bacterial; D000939:Epitopes