Development of a competitive chemiluminescence immunoassay using a
monoclonal antibody recognizing 3B of foot-and-mouth disease virus for
differentiating infected from vaccinated animals
Abstract
Foot-and-mouth disease (FMD) is a devastating animal disease.
Differentiation of infected from vaccinated animals (DIVA) is very
important for confirming suspected cases, evaluating the prevalence of
infection, certifying animals for trade and controlling the disease. In
this study, a competitive chemiluminescence immunoassay (3B-cCLIA) for
DIVA was developed for the rapid detection of antibodies against
non-structural proteins (NSPs) in different species of livestock animals
using monoclonal antibody 9E2 as a competitive antibody that recognizes
NSP 3B, which only needs to be washed once and takes 15 min. The cut-off
(50%), diagnosis sensitivity (97.20%, 95.71%, and 96.15%) and
diagnosis specificity (99.51%, 99.43%, and 98.36) of the assay were
estimated by testing a panel of known background sera from swine, cattle
and sheep. The accuracy rate of 3B-cCLIA was also validated and compared
with that of two commercial diagnostic kits. The early diagnostic
performance showed that antibodies to NSPs occurred later (approximately
1–2 days) than antibodies to structural proteins. Furthermore, NSP
antibodies present in animals vaccinated multiple times
(false-positive), especially in cattle and sheep, were confirmed, and
the false-positive rate increased with the number of vaccinations. These
results indicated that 3B-cCLIA is suitable to rapidly detect antibodies
against FMDV NSP 3B in a wide range of species for DIVA.