Prevalence of Neutralizing Antibodies to Japanese Encephalitis Virus among High-Risk Age Groups in South Korea, 2010

• Published in: PloS one Vol. 11; no. 1; p. e0147841
• Main Authors: Lee, Eun Ju, Cha, Go-Woon, Ju, Young Ran, Han, Myung Guk, Lee, Won-Ja, Jeong, Young Eui
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 25.01.2016; Public Library of Science (PLoS)
• Subjects: Adult; Adults; Age; Age groups; Aged; Agriculture; Antibodies; Antibodies, Neutralizing - blood; Antibodies, Neutralizing - immunology; Biology and Life Sciences; Children; Development and progression; Disease control; Disease prevention; Encephalitis; Encephalitis Virus, Japanese - immunology; Encephalitis, Japanese - epidemiology; Epidemics; Female; Forestry; Genetic aspects; Genomes; Humans; Immunity; Immunoassays; Immunoglobulins; Immunotherapy; Infections; Japanese encephalitis; Laboratories; Male; Medicine and Health Sciences; Middle Aged; Neutralization; Neutralization Tests; Neutralizing; Occupations; People and Places; Physiological aspects; Republic of Korea; Research and Analysis Methods; Risk Factors; Seroepidemiologic Studies; Vaccination; Vaccines; Vector-borne diseases; Viral infections; Viruses; West Nile virus; Republic of Korea; South Korea; Japan; Nepal; Taiwan
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0147841

After an extensive vaccination policy, Japanese encephalitis (JE) was nearly eliminated since the mid-1980s in South Korea. Vaccination in children shifted the affected age of JE patients from children to adults. However, an abrupt increase in JE cases occurred in 2010, and this trend has continued. The present study aimed to investigate the prevalence of neutralizing antibodies to the JE virus (JEV) among high-risk age groups (≥40 years) in South Korea. A plaque reduction neutralization test was conducted to evaluate the prevalence of neutralizing antibodies to JEV in 945 subjects within four age groups (30-39, 40-49, 50-59, and 60-69 years) in 10 provinces. Of the 945 enrolled subjects, 927 (98.1%) exhibited antibodies against JEV. No significant differences were found in the prevalence of neutralizing antibodies according to sex, age, or occupation. However, there were significant differences in the plaque reduction rate according to age and occupation; oldest age group had a higher reduction rate, and subjects who were employed in agriculture or forestry also had a higher value than the other occupations. We also found that three provinces (Gangwon, Jeonnam, and Gyeongnam) had a relatively lower plaque reduction rate than the other locations. In addition, enzyme-linked immunosorbent assays were conducted to determine recent viral infections and 12 (1.3%) subjects were found to have been recently infected by the virus [corrected]. In conclusion, the present study clearly indicated that the prevalence of neutralizing antibodies has been maintained at very high levels among adult age groups owing to vaccination or natural infections, or both. In the future, serosurveillance should be conducted periodically using more representative samples to better understand the population-level immunity to JE in South Korea.