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Open Access Methodology

Use of immuno-dominant epitope derived from genotype 4 as a diagnostic reagent for detecting the antibodies against Hepatitis E Virus

Xiu Bing-shui1, Feng Xiao-yan1, He Jing1, Chen Kun1, Liu Jing3, Dai Zhen-hua1, Yang Xi-Qin1, Wang Guo-hua1, Wang You-chun2, Zhang He-qiu1*, Song Xiao-guo1 and Zhu Cui-xia1

Author Affiliations

1 Institute of Basic Medical Sciences, Academy of military Medical Sciences, Taiping Road, Beijing, 100850, P.R. China

2 Department of Cell Biology, National Institute for the Control of Pharmaceutical and Biological Products, No. 2 Tiantanxili, Beijing, 100050, P.R. China

3 China National Center For Biotechnology Development, No. 6 West Fourth Ring Road, Beijing, 100036, P.R. China

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Virology Journal 2013, 10:131  doi:10.1186/1743-422X-10-131

Published: 25 April 2013

Abstract

Background

Despite the genotype 4 has become the dominant cause of hepatitis E disease in China, none antigen derived from genotype 4 of hepatitis E virus (HEV) was used in current commercial anti-HEV immunoassay, and the serological reactivity of antigen derive from genotype 4 is not well-charactered.

Methods

We expressed and purified the 4 main immuno-dominant epitopes derived from genotype 1 and 4 including ORF2 (410-621aa) of genotype 4, ORF3 (47-114aa) of genotype 4, ORF2 (396-606aa) of genotype 1 and ORF3 (56-123aa) of genotype 4.

Results

The ORF2 of genotype 4 displayed good diagnostics performance according to ROC analysis using in-house panel, and the immunoassays based the ORF2 of genotype 4 was then developed to detect the anti-HEV IgG antibodies and evaluated further in 530 anti-HEV IgG positive specimens and 380 negative specimens. The sensitivity and the specificity is 98.1% (520/530) and 94.7% (360/380) for immunoassay based on ORF2 of genotype 4, 96.6% (512/530) and 92.6% (352/380) for commercial immunoassay based on genotype 1. It is noted that all of the positive samples will be detected by combing two assays together. The anti-HEV immunoassays based on genotype 4 are in accordance with Chinese anti-HEV national standard,and show an good agreement of 95.8% with commercial assay (kappa=0.913, P=0.014).

Conclusions

The immunoassay based on ORF2G4 displays good performance, and combining assay based on genotype 1 together with genotype 4 will benefit the HEV diagnosis in large scale samples.

Keywords:
HEV; ORF2; ORF3; Genotype; Immunoassay