Improvement of indirect enzyme-linked immunosorbent assay for detection of Japanese encephalitis virus antibodies in swine sera
Dong-Kun Yang, Ha-Hyun Kim, Hyun-Ye Jo, Seung Heon Lee, Sang-Ho Jang, Sang-Oh Lee, Sung-Suk Choi, In-Soo Cho
Viral Disease Division, Animal and Plant Quarantine Agency, Gimcheon 39660, Korea
R&D Center, MEDIAN Diagnostics, Chuncheon 24399, Korea
Abstract: Japanese encephalitis (JE) is an important zoonosis caused by the mosquito-transmitted JE virus (JEV), which
is a causative agent of reproductive failure in pregnant sows. Detection of JEV antibodies in swine is performed by
hemagglutination inhibition (HI), virus neutralization (VN), and the plaque reduction neutralization test (PRNT). The
most stringent PRNT is the 90% endpoint PRNT (PRNT90). These conventional assays are difficult to carry out in
diagnostic laboratories with insufficient instruments or cell culture systems. An alternative assay that is easily conducted
and time efficient is required. In this study, we improved the indirect enzyme-linked immunosorbent assay (I-ELISA)
with clarified antigen for the detection of JEV antibodies. The I-ELISA results obtained from 175 swine serum samples
were compared with HI, VN, and PRNT90 results. The sensitivity of I-ELISA was 91.8%, 95.0%, and 94.7% compared
with HI, VN, and PRNT90 results, respectively. The specificity of I-ELISA was 92.2%, 94.7%, and 94.7% compared
with HI, VN, and PRNT90 results, respectively. Moreover, the I-ELISA results were significantly correlated with the
HI (r = 0.93), VN (r = 0.95), and PRNT90 (r = 0.92) results. These results suggest that the improved I-ELISA is useful
for serosurveillance of JEV in swine.