Protein A used in DELFIA for the determination of specific antibodies.
The conditions of protein A labelling with Eu chelates were studied. The conjugates obtained were compared with those from horseradish peroxidase used conventionally in immunochemical practice. Protein A-Eu conjugates were obtained by a method applied previously for antibody labelling with indium and europium chelates using the bicyclic dianhydride of diethylenetriaminepenta-acetic acid (DADTPA) with some modifications. The Eu-labeled protein A ensured a sensitivity of the IgG determination at the level of 2 ng/ml and a dynamic range of the determination from 3 to 1000 ng/ml, which significantly exceed analogous values for the protein A-peroxidase conjugates. The Eu-labeled protein A was used for the determination of antibodies to Francisella tularensis in the sera of humans vaccinated against tularemia. The assay values exceeded by 10-40-fold the results of an ELISA in sensitivity. It was deduced that the Eu-labeled protein A can be effectively used for the determination of antibodies specific to a tularemia causative agent. In particular, this compound can be useful for the determination of specific antibodies in low immune sera.
Guzaeva
T V
TV
Institute of Immunology, State Concern Biopreparation, Lyubuchany, Moscow Region, Russian Federation.
Komarov
A M
AM
Yurov
S V
SV
Pchelintsev SYu
Chudinov
A V
AV
Afanasiev
S S
SS
D000907:Antibodies, Bacterial / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D005063:Europium; D005455:Fluorescent Antibody Technique; D005604:Francisella tularensis / Q000276:immunology; D006801:Humans; D011994:Recombinant Proteins; D013205:Staphylococcal Protein A; D014406:Tularemia / Q000276:immunology
D000907:Antibodies, Bacterial; D011994:Recombinant Proteins; D013205:Staphylococcal Protein A; D005063:Europium