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Development and partial validation of a recombinant E2-based indirect ELISA for detection of specific IgM antibody responses against classical swine fever virus
- Li, Wenliang, Mao, Li, Yang, Leilei, Zhou, Bin, Jiang, Jieyuan
- Journal of virological methods 2013 v.191 no.1 pp. 63-68
- Classical swine fever virus, antibodies, antigens, blood serum, enzyme-linked immunosorbent assay, immunoglobulin G, immunoglobulin M, neutralization tests, piglets, rabbits
- Detecting classical swine fever virus specific antibody responses is critical for prevention and control of CSF. In this study, a ΔE2-based indirect ELISA was developed to detect specific IgM antibodies against CSFV. The optimized conditions that were determined experimentally are: a ΔE2 antigen concentration of 0.5μg/ml, a serum sample dilution of 1/100 incubated at 37°C for 1.5h, and a HRP conjugated rabbit anti-pig IgM dilution of 1/50,000 incubated at 37°C for 1h. Three hundred clinical sera were tested with ΔE2-IgM-ELISA and IDEXX ELISA and the positive rates were 77.3% (232/300) and 71.7% (215/300), respectively. Concordance rate between them was 80.3% (241/300). The 59 inconsistent sera were tested further: among the 21 IDEXX ELISA +/ΔE2-IgM-ELISA − and 38 IDEXX ELISA +/ΔE2-IgM-ELISA − samples, 17 and 24 were determined positive by virus neutralization test; 15 and 25 were tested positive by ΔE2-IgG-ELISA, respectively. In addition, the E2-specific IgM antibody response in 15 vaccinated piglets could be detected 2 weeks post-vaccination and earlier than specific IgG antibody. It increased regularly and reached high levels by 6 weeks post-vaccination. The ΔE2-IgM-ELISA could be used for clinical detection and for exploring the kinetics of IgM antibody response.