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.
Institute of Immunology, State Concern Biopreparation, Lyubuchany, Moscow Region, Russian Federation.
T V
TV
Guzaeva
A M
AM
Komarov
S V
SV
Yurov
Pchelintsev SYu
A V
AV
Chudinov
S S
SS
Afanasiev
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