Abstract
Hepatitis E virus (HEV) is classified within the family Hepeviridae, genus Hepevirus. HEV genotype 3 (Gt3) infections are endemic in pigs in Western Europe and in North and South America and cause zoonotic infections in humans. Several serological assays to detect HEV antibodies in pigs have been developed, at first mainly based on HEV genotype 1 (Gt1) antigens. To develop a sensitive HEV Gt3 ELISA, a recombinant baculovirus expression product of HEV Gt3 open reading frame-2 was produced and coated onto polystyrene ELISA plates. After incubation of porcine sera, bound HEV antibodies were detected with anti-porcine anti-IgG and anti-IgM conjugates. For primary estimation of sensitivity and specificity of the assay, sets of sera were used from pigs experimentally infected with HEV Gt3. For further validation of the assay and to set the cutoff value, a batch of 1100 pig sera was used. All pig sera were tested using the developed HEV Gt3 assay and two other serologic assays based on HEV Gt1 antigens. Since there is no gold standard available for HEV antibody testing, further validation and a definite setting of the cutoff of the developed HEV Gt3 assay were performed using a statistical approach based on Bayes' theorem. The developed and validated HEV antibody assay showed effective detection of HEV-specific antibodies. This assay can contribute to an improved detection of HEV antibodies and enable more reliable estimates of the prevalence of HEV Gt3 in swine in different regions.
Highlights
Hepatitis E virus (HEV) is a small nonenveloped RNA virus of approximately 7.2 kb, and has been classified within the family Hepeviridae, genus Hepevirus
HEV ELISA development As described in Material and Methods, several protocols were tested to set up an immunoassay based on HEV genotype 3 (Gt3) recombinant antigen
The results showed slight differences in the kinetics of anti-HEV antibody detection, but seroconversion of HEV-infected pigs was detected with both detection methods (Figure 1)
Summary
Hepatitis E virus (HEV) is a small nonenveloped RNA virus of approximately 7.2 kb, and has been classified within the family Hepeviridae, genus Hepevirus. Four mammalian genotypes (Gt1-4) were identified in the 1990s, and avian HEV had been identified before that [1]. Gt1 and Gt2 are found exclusively in humans and are responsible for large waterborne epidemics and sporadic cases in endemic regions (Asia, India, Africa, and Mexico) [1]. Gt1 and Gt2 can be divided further into five (a-e) and two (a and b) subtypes, respectively. Gt3 and Gt4 are responsible for sporadic cases in humans and are widespread in animals. For HEV Gt3, it is assumed that zoonotic transmission plays an important role in human infections [3]. Genotypes 3 and 4 seem more variable and can be divided into 10 (a-j) and 7 (a-g) subgenotypes, respectively [4]
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