Seroprevalence of anti-hepatitis E virus (HEV) in a Korean population: comparison of two commercial anti-HEV assays
© Park et al.; licensee BioMed Central Ltd. 2012
Received: 16 February 2012
Accepted: 22 June 2012
Published: 22 June 2012
Hepatitis E virus (HEV) has emerged as an important cause of epidemic and sporadic acute viral hepatitis worldwide. This study investigated the seroprevalence of anti-HEV in a Korean population and compared the performance of two commercially available anti-HEV assays.
A total 147 health-check examinees were randomly sampled as matched to the age- and sex- adjusted standard population based on the Korean National Census of 2007. Serum immunoglobulin G anti-HEV was determined by using the Genelabs assay (Genelabs, Singapore) and the Wantai assay (Wantai, Beijing, China).
The overall anti-HEV seroprevalence was 23.1% (95% CI, 16.1-30.1%) using the Wantai assay and 14.3% (95% CI, 8.3-20.3%) using the Genelabs assay. Only 12 samples (8.1%) were positive for anti-HEV as measured by both assays; agreement between the two assays was poor (kappa value of 0.315). The anti-HEV seroprevalence increased with age from 2% and 3% in the people younger than 20-years-of-age to 34.6% and 42.3% in those over 59-years-of-age by the Genelabs and Wantai assay, respectively.
The HEV seroprevalence in Korean population is about 20% overall, with seroprevalence increasing in this population with increasing age. There was poor concordance in the results of the Genelabs and Wantai assays, which warrants further study concerning a reliable diagnostic test for the diagnosis of hepatitis E.
KeywordsHepatitis E virus Seroprevalence Anti-HEV assay Korea
Hepatitis E virus (HEV) is an emerging disease of global importance as a major cause of enterically transmitted hepatitis . After its discovery in 1983 , HEV was characterized as a non-enveloped, single stranded, positive sense RNA virus classified as a member of the Hepeviridae family, Hepevirus genus.
The epidemiology of HEV infection displays two patterns. The first is an outbreak pattern in areas of high endemicity (primarily via water-borne or fecal-to-oral transmission). The second is a sporadic pattern that occurs worldwide via zoonotic transmission and food borne transmission. Hepatitis E is a serious public health problem responsible for over 50% of acute viral hepatitis cases  in endemic countries, which includes large parts of Asia, Africa, the Mediterranean region, Mexico, and South America . In contrast, HEV infection has previously been considered rare in developed countries , but is far more common than previously recognized [6, 7]. Zoonotic transmission, especially from pigs, has been suggested . However, the true burden of infection and its implication on public health impact remain undefined.
In developed countries, anti-HEV immunoglobulin G (IgG) prevalence rates range between 3% to above 20% [7, 9, 10]. These appear to be higher than those expected from the low rate of clinically evident hepatitis E disease in developed countries, suggesting that subclinical or unrecognized infection is common . Although several cases of imported and locally acquired hepatitis E have been reported in Korea, the anti-HEV seroprevalence data have not been available due to lack of disease recognition and to the limited availability of diagnostic tools .
Several anti-HEV assays have been developed and are available for use. However, the performance of each anti-HEV assay has not been well studied. One study  reported highly variable results among the different assays, which suggested that the diagnosis of HEV infection using anti-HEV tests should be made with caution. Findings from a comparison of two commercially available IgG anti-HEV enzyme-linked immunosorbent assay (EIA) kits – the Genelabs EIA (Genelabs, Singapore) and the Wantai EIA (Wantai Biological Pharmacy Enterprise, Beijing, China) – demonstrated that the Wantai EIA was more sensitive than the Genelabs EIA, and produced positive results for a longer time post-infection . Despite these findings, the Genelabs anti-HEV EIA remains the more popular assay.
The aims of this study were to investigate the seroprevalence of anti-HEV and its related factors in a Korean population, and to again compare the results of the two aforementioned commercially available serological assays for the detection of HEV-specific IgG.
Subjects and serum samples
A total of 484 health-check examinees visiting the Health Promotion Center of Seoul National University Bundang Hospital from June 2006 to September 2006 and agreed to participate in this study were enrolled. Among them, 147 sera were randomly selected by matching the subjects to the age- and sex- adjusted standard population of the Korean National Census of 2007. In detail, 484 subjects were first allocated into the each category of age in decades and sex, and then 147 were randomly selected according to the proportions of the standard population in each category. Serum samples were stored at −70°C until the analysis. Informed consent was obtained from all participants and the study protocol was approved by the Institutional Review Board of Seoul National University Bundang Hospital.
Measurement of anti-HEV IgG using the two commercial assays
The Genelabs HEV IgG enzyme-linked immunosorbent assay (ELISA) and the Wantai HEV IgG ELISA were used to detect IgG anti-HEV in sera. The Genelabs assay detects antibodies directed at a mixture of recombinant peptides specified by the open reading frame (ORF) 2 and ORF 3 obtained from two different strains of HEV: one from Mexico (genotype 2) and the other from Burma (genotype 1) . The Wantai assay uses a recombinant peptide corresponding to amino acid residues 396–606 of the major structural protein specified by ORF2 derived from a Chinese isolate of HEV (genotype 4) . Anti-HEV IgG in all serum samples were examined with both the Genelabs and Wantai assay, according to manufacturer’s instructions, with three negative and two positive control wells included on each plate. The optical density (OD) of each sample was determined at 450 nm. Samples with an OD greater than the cut-off value were determined to be positive. All serum samples were tested in duplicate and the cut-off value was calculated to be the mean absorbance value of the negative control plus 0.5 for the Genelabs assay and plus 0.16 for the Wantai assay, according to the manufacturer’s instructions.
Descriptive statistics were reported and agreement between two assays was quantified with the kappa statistic. The chi-squared test and paired T-test were used to determine whether any patient characteristics were associated with different results in the two assays. Differences were considered to be statistically significant at P < 0.05. The statistical analyses were carried out using the SPSS statistical program, version (SPSS,Chicago, IL, USA).
The study subjects included 72 males and 75 females, with an overall mean age of 45 years. These characteristics were compatible with the data from the Korean National Census of 2007. The mean body mass index of the subjects was 23.0, and the mean serum levels of alanine aminotransferase and total bilirubin were 28.4 IU/mL and 1.0 mg/dL, respectively. The hepatitis B virus surface antigen (HBsAg) positive rate was 3.8%, and the anti-hepatitis C virus antibody positive rate was zero.
Comparison of seropositivity of anti-HEV IgG measured using the two immunoassays
Total, n (%)
Total, n (%)
Anti-HEV seropositive rates according to age groups and gender
Seropositivities for :
Wantai % (95% CI)
Genelabs % (95% CI)
Age group, years
In this study, we evaluated the anti-HEV IgG positive rate in a Korean adult population composed of 147 health check examinees, age- and sex-adjusted to the standard population based on the Korean National Census of 2007. The seropositivity of anti-HEV in our study subjects was 23.1% in the Wantai assay and 14.3% in the Genelabs assay. The agreement of the results between assays was poor, with a κ value of 0.315. The anti-HEV positivity and mean OD values of anti-HEV measured using both assays significantly increased with increasing age.
Korea is not an endemic area of hepatitis E, and less than 20 cases of acute hepatitis E cases have been reported in South Korea since 2002 [17–20]. Most of these cases were of Korean origin rather than having been imported from highly endemic areas. Among them, only a few cases demonstrated HEV RNA, which identified HEV genotype 3 and genotype 4, and genotype 3 HEV sequences isolated from human cases were nearly identical to those from pigs in Korea. Moreover, we recently reported a case of genotype 4 HEV hepatitis after ingestion of raw bile juice of wild boar, suggesting zoonotic transmission of HEV in Korea [21, 22]. Therefore, at least two HEV genotypes already circulate in Korea, and it is likely that more cases will be identified with the increased recognition of HEV.
Previous studies on the seropositivity of anti-HEV in Korea reported a positive rate between 8% and 17% in the various populations, based on blood donors, or healthy adults visiting some diagnostic laboratories. However, those study subjects had not been adjusted to the standard population and even no detailed demographic information had been provided; all these preliminary studies had only used the Genelabs assay [23–25]. Therefore, direct comparison of our data to the previous results was difficult. Recently, the comparative seroprevalence in 1,500 people over 40-years-of-age living in Japan, Korea, and China were reported using anEIA developed in Japan . The anti-HEV positivity was 50.7% in Korean Chinese, 34% in South Koreans, and 14.3% in Koreans living in Japan. In our study, the seroprevalence of anti-HEV in adults over 40-years-of-age was 16.9% in the Genelabs assay and 30.3% in the Wantai assay, which was similar to the previous results.
Presently, older age groups tended to have higher HEV seroprevalence rates by both assays, and the differences were statistically significant. Age has been correlated with higher HEV seroprevalence rates . IgG anti-HEV titers remain high from 1–4.5 years after the acute phase , and one study detected anti-HEV IgG in about 47% of individuals 14 years after acute HEV infection . These persistent anti-HEV IgG can account for the high rates of seroprevalence in older subjects among the general population . Therefore, differences in seroprevalence rates between different populations must be interpreted with caution , because demographic variables, such as age, are related to the prevalence, and because the assays vary in their sensitivity  in the absence of standardized commercially available confirmatory assays, such as reverse transcription-PCR.
Several commercial serological assays for the detection of anti-HEV IgG are available . Among them, the Genelabs EIA has been the most commonly used worldwide. Its antigens use polypeptides from the C-terminal ORF3 and ORF2 domains of HEV genotypes 1 and 2 . The Genelabs assay, based on genotypes 1 and 2, vary greatly in sensitivity (50%-90%) despite an excellent specificity (93%-100%) [15, 33–35]. Moreover, the experience and test performance with this assay has come mainly from regions of high endemicity and western countries. In our results, the agreement between the Wantai and the Genelabs assays was poor (κ value = 0.315), and the Wantai assay displayed higher seropositivity than the Genelabs assay, which may suggest the higher sensitivity of the Wantai assay. However, we did not use the standard serum in our study, so that the sensitivity and specificity in our study cannot be assessed. Recently, Bendall et al.  compared the performance of Genelabs and Wantai HEV IgG EIA kit using World Health Organization standard sera; the Wantai assay was more sensitive than the Genelabs assay, and continued to test infected individuals as positive for longer periods post-infection. The authors also tested 500 blood samples obtained from blood donors in the United Kingdom using both assays; the Wantai assay resulted in a substantially higher estimate of seroprevalence (16.2%) than that of Genelabs (3.6%) . Moreover, the Wantai kit has been reported to be more sensitive because the peptides used in the Wantai assay may associate into dimers, which react more strongly with HEV reactive sera than the linear monomeric antigens used in the Genelabs assay . The Wantai anti-HEV IgG ELISA uses a peptide encoded by a structural region of ORF-2 of HEV genotype 4. Specificity is difficult to assess in situations other than acute hepatitis E because there is no gold standard for checking the specificity of the current anti-HEV ELISA. Both assays have been compared to Western blots and other assays in population-based studies. The specificity of the Genelabs assay was 97%  and that of the Wantai assay was 99.6% [16, 38]. Accepting that both assays have similar specificities, it is reasonable to assume that the Wantai assay gives a more reliable estimate of anti-HEV seropositivity rates than the Genelabs assay.
The results of this study should be interpreted in the context of its limitations. First, the data were obtained from a single center using cross-sectional design, so that time trends could not be addressed. However, direct measurement of incidence of hepatitis E is difficult because infection is most often asymptomatic and unrecognized. Second, we were unable to assess the distribution of risk factors in our study population, such as profession, hobbies, diet, social status, residence, or travel history. Further studies are required to clarify the epidemiology and risk factors for HEV infection in Korea.
In conclusion, the prevalence of anti-HEV in Korean adult population was about 20%, with higher prevalence at increased age. However, different assays for the detection of anti-HEV IgG result in significantly different results. Therefore, future studies on the development of standard diagnostic tests and their validation are warranted.
This study was supported by research grant 02-2009-039 from Seoul National University Bundang Hospital.
- Purcell RH, Emerson SU: Hepatitis E: an emerging awareness of an old disease. J Hepatol. 2008, 48: 494-503. 10.1016/j.jhep.2007.12.008.View ArticlePubMedGoogle Scholar
- Balayan MS, Andjaparidze AG, Savinskaya SS, Ketiladze ES, Braginsky DM, Savinov AP, Poleschuk VF: Evidence for a virus in non-A, non-B hepatitis transmitted via the fecal-oral route. Intervirology. 1983, 20: 23-31. 10.1159/000149370.View ArticlePubMedGoogle Scholar
- Yarbough PO: Hepatitis E virus. Advances in HEV biology and HEV vaccine approaches. Intervirology. 1999, 42: 179-184. 10.1159/000024978.View ArticlePubMedGoogle Scholar
- Aggarwal R, Krawczynski K: Hepatitis E: an overview and recent advances in clinical and laboratory research. J Gastroenterol Hepatol. 2000, 15: 9-20. 10.1046/j.1440-1746.2000.02006.x.View ArticlePubMedGoogle Scholar
- Emerson SU, Purcell RH: Running like water–the omnipresence of hepatitis E. N Engl J Med. 2004, 351: 2367-2368. 10.1056/NEJMp048285.View ArticlePubMedGoogle Scholar
- Dalton HR, Bendall R, Ijaz S, Banks M: Hepatitis E: an emerging infection in developed countries. Lancet Infect Dis. 2008, 8: 698-709. 10.1016/S1473-3099(08)70255-X.View ArticlePubMedGoogle Scholar
- Aggarwal R, Naik S: Epidemiology of hepatitis E: current status. J Gastroenterol Hepatol. 2009, 24: 1484-1493. 10.1111/j.1440-1746.2009.05933.x.View ArticlePubMedGoogle Scholar
- Meng XJ, Wiseman B, Elvinger F, Guenette DK, Toth TE, Engle RE, Emerson SU, Purcell RH: Prevalence of antibodies to hepatitis E virus in veterinarians working with swine and in normal blood donors in the United States and other countries. J Clin Microbiol. 2002, 40: 117-122. 10.1128/JCM.40.1.117-122.2002.View ArticlePubMedPubMed CentralGoogle Scholar
- Dalton HR, Stableforth W, Thurairajah P, Hazeldine S, Remnarace R, Usama W, Farrington L, Hamad N, Sieberhagen C, Ellis V, et al: Autochthonous hepatitis E in Southwest England: natural history, complications and seasonal variation, and hepatitis E virus IgG seroprevalence in blood donors, the elderly and patients with chronic liver disease. Eur J Gastroenterol Hepatol. 2008, 20: 784-790. 10.1097/MEG.0b013e3282f5195a.View ArticlePubMedGoogle Scholar
- Faramawi MF, Johnson E, Chen S, Pannala PR: The incidence of hepatitis E virus infection in the general population of the USA. Epidemiol Infect. 2011, 139: 1145-1150. 10.1017/S0950268810002177.View ArticlePubMedGoogle Scholar
- Schwartz E, Jenks NP, Van Damme P, Galun E: Hepatitis E virus infection in travelers. Clin Infect Dis. 1999, 29: 1312-1314. 10.1086/313430.View ArticlePubMedGoogle Scholar
- Ahn JM, Kang SG, Lee DY, Shin SJ, Yoo HS: Identification of novel human hepatitis E virus (HEV) isolates and determination of the seroprevalence of HEV in Korea. J Clin Microbiol. 2005, 43: 3042-3048. 10.1128/JCM.43.7.3042-3048.2005.View ArticlePubMedPubMed CentralGoogle Scholar
- Mast EE, Alter MJ, Holland PV, Purcell RH: Evaluation of assays for antibody to hepatitis E virus by a serum panel. Hepatitis E Virus Antibody Serum Panel Evaluation Group. Hepatology. 1998, 27: 857-861. 10.1002/hep.510270331.View ArticlePubMedGoogle Scholar
- Bendall R, Ellis V, Ijaz S, Ali R, Dalton H: A comparison of two commercially available anti-HEV IgG kits and a re-evaluation of anti-HEV IgG seroprevalence data in developed countries. J Med Virol. 2010, 82: 799-805. 10.1002/jmv.21656.View ArticlePubMedGoogle Scholar
- Myint KSA, Endy TP, Gibbons RV, Laras K, Mammen MP, Sedyaningsih ER, Seriwatana J, Glass JS, Narupiti S, Corwin AL: Evaluation of diagnostic assays for Hepatitis E virus in outbreak settings. J Clin Microbiol. 2006, 44: 1581-1583. 10.1128/JCM.44.4.1581-1583.2006.View ArticlePubMedPubMed CentralGoogle Scholar
- Li RC, Ge SX, Li YP, Zheng YJ, Nong Y, Guo QS, Zhang J, Ng MH, Xia NS: Seroprevalence of hepatitis E virus infection, rural southern People's Republic of China. Emerg Infect Dis. 2006, 12: 1682-1688. 10.3201/eid1211.060332.View ArticlePubMedPubMed CentralGoogle Scholar
- Kim NJ, Lee JS, Kim KA, Lee HR, Oh JW, Cho YD, Lee WJ, Baik HW, Jeon YB, Kim CY: A case of acute hepatitis E. Korean J Hepatol. 2002, 8: 312-316.Google Scholar
- Kim DH, Park H, Moon SW, Jeong JH, Yang HS, Kim do H, Kim HD: Three sporadic cases of acute hepatitis E. Korean J Gastroenterol. 2007, 50: 121-125.PubMedGoogle Scholar
- Lim JW, Park CS, Ahn JM, Yu MH, Kim TS, Lim YS, Chung SW, Kim GM, Chung YH, Lee YS: Nine cases of sporadic acute hepatitis E in Korea. Korean J Hepatol. 2006, 12: 230-236.PubMedGoogle Scholar
- Kang HM, Jeong SH, Kim JW, Lee D, Choi CK, Park YS, Hwang JH, Kim N, Lee DH: Recent etiology and clinical features of acute viral hepatitis in a single center of Korea. Korean J Hepatol. 2007, 13: 495-502. 10.3350/kjhep.2007.13.4.495.View ArticlePubMedGoogle Scholar
- Kim YM, Jeong SH, Kim JY, Song JC, Lee JH, Kim JW, Yun H, Kim JS: The first case of genotype 4 hepatitis E related to wild boar in South Korea. J Clin Virol. 2011, 50: 253-256. 10.1016/j.jcv.2010.11.005.View ArticlePubMedGoogle Scholar
- Yun H, Kim JS, Lee HJ, Jeong SH, Park SJ, Hwang SG, Kang SK, Jee Y, Kim JH: The complete genome sequence and molecular analysis of human hepatitis E virus genotype IV identified from a Korean patient. Arch Virol. 2010, 155: 1003-1008. 10.1007/s00705-010-0661-9.View ArticlePubMedGoogle Scholar
- Shin HK, Yoon JD, Chung YH, Kim MB, Suh SD, Kim JS: Prevalence of anti-Hepatitis E virus(HEV) on Korea, 1991. J of Kor Soc of Virology. 1992, 22: 155-162.Google Scholar
- Byun KS, Yeon JE, Kwon S, Bak YT, Kim JH, Kwon SY, Lee CH: Prevalence of IgG and IgM anti-HEV in patients with acute hepatitis of unknown causes and healthy adults in Korea. Korean J Gastroenterol. 1995, 28: 661-668.Google Scholar
- Choi IS, Kwon HJ, Shin NR, Yoo HS: Identification of swine Hepatitis E virus (HEV) and prevalence of anti-HEV antibodies in swine and human populations in Korea. J Clin Microbiol. 2003, 41: 3602-3608. 10.1128/JCM.41.8.3602-3608.2003.View ArticlePubMedPubMed CentralGoogle Scholar
- Taniguchi M, Kim SR, Mishiro S, Takahashi K, Shin MH, Yun H, Park MS, Li ZM, Kim MK, Fang J: Epidemiology of hepatitis E in Northeastern China, South Korea and Japan. J Infect. 2009, 58: 232-237. 10.1016/j.jinf.2009.01.011.View ArticlePubMedGoogle Scholar
- Zhu G, Qu Y, Jin N, Sun Z, Liu T, Lee H, Tian M, Wang T: Seroepidemiology and molecular characterization of hepatitis E virus in Jilin, China. Infection. 2008, 36: 140-146. 10.1007/s15010-007-7130-8.View ArticlePubMedGoogle Scholar
- Favorov MO, Khudyakov YE, Mast EE, Yashina TL, Shapiro CN, Khudyakova NS, Jue DL, Onischenko GG, Margolis HS, Fields HA: IgM and IgG antibodies to hepatitis E virus (HEV) detected by an enzyme immunoassay based on an HEV-specific artificial recombinant mosaic protein. J Med Virol. 1996, 50: 50-58. 10.1002/(SICI)1096-9071(199609)50:1<50::AID-JMV10>3.0.CO;2-1.View ArticlePubMedGoogle Scholar
- Khuroo MS, Kamili S, Dar MY, Moecklii R, Jameel S: Hepatitis E and long-term antibody status. Lancet. 1993, 341: 1355-PubMedGoogle Scholar
- Arankalle VA, Tsarev SA, Chadha MS, Alling DW, Emerson SU, Banerjee K, Purcell RH: Age-specific prevalence of antibodies to hepatitis A and E viruses in Pune, India, 1982 and 1992. J Infect Dis. 1995, 171: 447-450. 10.1093/infdis/171.2.447.View ArticlePubMedGoogle Scholar
- Mushahwar IK: Hepatitis E virus: molecular virology, clinical features, diagnosis, transmission, epidemiology, and prevention. J Med Virol. 2008, 80: 646-658. 10.1002/jmv.21116.View ArticlePubMedGoogle Scholar
- Panda SK, Thakral D, Rehman S: Hepatitis E virus. Rev Med Virol. 2007, 17: 151-180. 10.1002/rmv.522.View ArticlePubMedGoogle Scholar
- Mitsui T, Tsukamoto Y, Suzuki S, Yamazaki C, Masuko K, Tsuda F, Takahashi M, Tsatsralt-Od B, Nishizawa T, Okamoto H: Serological and molecular studies on subclinical hepatitis E virus infection using periodic serum samples obtained from healthy individuals. J Med Virol. 2005, 76: 526-533. 10.1002/jmv.20393.View ArticlePubMedGoogle Scholar
- Herremans M, Bakker J, Duizer E, Vennema H, Koopmans MPG: Use of serological assays for diagnosis of Hepatitis E virus genotype 1 and 3 infections in a setting of low endemicity. Clin Vaccine Immunol. 2007, 14: 562-568. 10.1128/CVI.00231-06.View ArticlePubMedPubMed CentralGoogle Scholar
- Ghabrah TM, Tsarev S, Yarbough PO, Emerson SU, Strickland GT, Purcell RH: Comparison of tests for antibody to hepatitis E virus. J Med Virol. 1998, 55: 134-137. 10.1002/(SICI)1096-9071(199806)55:2<134::AID-JMV9>3.0.CO;2-3.View ArticlePubMedGoogle Scholar
- Zhang J, Ge SX, Huang GY, Li SW, He ZQ, Wang YB, Zheng YJ, Gu Y, Ng MH, Xia NS: Evaluation of antibody-based and nucleic acid-based assays for diagnosis of hepatitis E virus infection in a rhesus monkey model. J Med Virol. 2003, 71: 518-526. 10.1002/jmv.10523.View ArticlePubMedGoogle Scholar
- Bouwknegt M, Engel B, Herremans MMPT, Widdowson MA, Worm HC, Koopmans MPG, Frankena K, De Roda Husman AM, De Jong MCM, Van Der Poel WHM: Bayesian estimation of hepatitis E virus seroprevalence for populations with different exposure levels to swine in The Netherlands. Epidemiol Infect. 2007, 136: 567-576.PubMedPubMed CentralGoogle Scholar
- Khan A, Tanaka Y, Kurbanov F, Elkady A, Abbas Z, Azam Z, Subhan A, Razza S, Hamid S, Jafri W: Investigating an outbreak of acute viral hepatitis caused by hepatitis E virus variants in Karachi, South Pakistan. J Med Virol. 2011, 83: 622-629. 10.1002/jmv.22036.View ArticlePubMedGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2334/12/142/prepub
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