A solid-phase competition ELISA for measuring antibody to foot-and-mouth disease virus

A solid-phase competition ELISA has been developed to measure antibodies to foot-and-mouth disease (FMD) virus and has been validated using an extensi ve range of sera from cattle. The assay uses polyclonal antisera and inacti vated purified 146S antigens of FMD virus and was compared with the liquid- phase blocking ELISA and the virus neutralisation test on a range of serum sets. When examining test sera at a 1:5 dilution with a cut-off point of 30 % inhibition of reaction. the solid-phase competition ELISA was as sensitiv e as the liquid-phase blocking ELISA for sera from infected or vaccinated a nimals. The limit of detection of the solid-phase ELISA was similar to that of the liquid-phase assay and both tests had lower limit of detection (i.e , were able to detect lower amounts of antibody) than the virus neutralisat ion test. The specificity of the solid-phase ELISA was considerably higher than that of the liquid-phase blocking ELISA and almost equivalent to that of the virus neutralisation test. The assay thus retains the sensitivity of the liquid-phase blocking ELISA whilst being easier to use, more robust an d specific. and therefore offers an improvement for FMD virus antibody dete ction. (C) 2001 Elsevier Science B.V. All rights reserved.