- Comparison of Four Serological Tests for Detecting Antibodies to Japanese Encephalitis Virus after Vaccination in Children
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Go Woon Cha, Jung Eun Cho, Young Ran Ju, Young-Jin Hong, Myung Guk Han, Won-Ja Lee, Eui Yul Choi, Young Eui Jeong
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Osong Public Health Res Perspect. 2014;5(5):286-291. Published online October 31, 2014
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DOI: https://doi.org/10.1016/j.phrp.2014.08.003
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 Abstract
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- Objectives
Several different methods are currently used to detect antibodies to Japanese encephalitis virus (JEV) in serum samples or cerebrospinal fluid. These methods include the plaque reduction neutralization test (PRNT), the hemagglutination inhibition (HI) test, indirect immunofluorescence assay (IFA), and enzyme-linked immunosorbent assay (ELISA). The purpose of this study was to compare the performance of each method in detecting vaccine-induced antibodies to JEV.
Methods
The study included 29 children who had completed a primary immunization schedule with an inactivated vaccine against JEV derived from mouse brain (n = 15) or a live attenuated SA14-14-2 vaccine (n = 14). Serum samples were collected between 3 months and 47 months after the last immunization. The serum samples were tested by performing the PRNT, HI test, in-house IFA, and commercial ELISA. The antibody detection rates were compared between tests.
Results
All 29 serum samples were positive with the PRNT, showing antibody titers from 1:20 to 1:2560. The HI test showed positive rates of 86.7% (13/15) and 71.4% (10/14) in the inactivated and live attenuated vaccine groups, respectively. The results of the IFA for immunoglobulin (Ig)G were positive in 53.3% (8/15) of children in the inactivated vaccine group and 35.7% (5/14) in the live attenuated vaccine group. Neither the IFA nor ELISA detected JEV IgM antibodies in any of the 29 children.
Conclusion
These results show that detection rates of vaccine-induced antibodies to JEV have a wide range (0–100%) depending on the testing method as well as the time since immunization and individual differences between children. These findings are helpful in interpreting serological test results for the diagnosis of Japanese encephalitis in situations where vaccines are widely administered.
- Travel-Associated Chikungunya Cases in South Korea during 2009–2010
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Go Woon Cha, Jung Eun Cho, Eun Ju Lee, Young Ran Ju, Myung Guk Han, Chan Park, Young Eui Jeong
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Osong Public Health Res Perspect. 2013;4(3):170-175. Published online June 30, 2013
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DOI: https://doi.org/10.1016/j.phrp.2013.04.008
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1,466
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- Objectives
Chikungunya (CHIK) has been classified as a communicable disease group IV in South Korea since late 2010. Based on this, we investigated the extent of imported cases of CHIK in dengue-suspected individuals returning from dengue-endemic regions.
Methods
A total of 486 dengue-suspected serum samples were screened for CHIK by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Further RT-PCR-positive samples were used for the viral culture, and CHIK was subsequently confirmed by sequence analysis of the culture samples.
Results
Five out of 107 dengue-positive samples were found to be positive for CHIK and 15 out of 379 dengue-negative samples were found to be positive for CHIK by immunoglobulin M ELISA. Further, a CHIK virus was isolated from one of the two RT-PCR-positive sera by cell culture and confirmed by sequence analysis.
Conclusion
The present study documents the first evidence of travel-associated CHIK infection in South Korea. Considering the intense international traffic between countries, our finding emphasizes the urgent need for active patient and vector surveillance for timely response to reduce the introduction of CHIK in Korea.
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