Development and application of a high sensitivity immunochromatographic
test strip for detecting classical swine fever virus antibody
Abstract
Classical swine fever (CSF) is caused by classical swine fever virus
(CSFV) and has led to huge ecnomic losses for the pig industry
worldwide. Although vaccination and other control measures have been
carried out, it is essential to establish a rapid and valid method for
CSF vaccination monitoring and clinical diagnosis. CSFV E2 protein has
been well-known as a major antigen for antibody detection. It is
significant to improve affinity between E2 protein and CSFV antibody for
a better performance of detection method. In this study, a recombinant
E2 extracellular protein (aa 1-331), which has a native homodimer
conformation and has a high affinity with anti-CSFV-E2 monoclonal
antibody WH303, was expressed using Bac-to-Bac baculovirus expression
system. A novel immunochromatographic test strip based on the
recombinant CSFV E2 protein was developed for CSFV antibody detection.
The sensitivity of this strip for detecting CSFV standard positive serum
was 1:102400, 4 times higher than that of the previously developed CnC2
test strip. No cross reaction with antibodies of other swine viruses was
observed. The detection of clinical swine serum samples (n=138)
demonstrated that the agreements of this E2 test strip with three
commercial ELISA kits were 88.40% (122/138), 86.23% (119/138), and
96.38% (133/138), respectively. Our data indicated that a novel E2 test
strip with higher sensitivity has been developed and can be applied for
clinical sample detections, providing a new powerful and simple approach
for CSFV antibody monitoring.