A New Artificial Antigen of the Hepatitis E Virus

Abstract

An artificial antigen composed of 12 small antigenic regions derived from the ORF2 and ORF3 HEV proteins was designed. The gene encoding for this artificial antigen was assembled from synthetic oligonucleotides by a new method called Restriction Enzyme-Assisted Ligation (REAL). The diagnostic relevance of this second generation HEV mosaic protein (HEV MA-II) was demonstrated by testing this antigen against a panel of 142 well defined anti-HEV positive and anti-HEV negative serum samples. The data obtained in this study support the substantial diagnostic potential of this HEV mosaic antigen.

Keywords:

• Artificial antigen
• Enzyme immunoassay
• Hepatitis E

Notes

S/C-average Signal to Cutoff ratio.

NT-not tested because these MA-II peptides cover junctions between antigenic regions included in the HEV MA-II (see Fig 1).

*Peptides derived from the HEV ORF2 and ORF3 proteins (see Materials and Methods).

¹Peptide 4269 (see Materials and Methods) was tested.

²Peptide 4405 was tested.

³Peptide 4274 was tested.

⁴Peptide 4350 was tested.

⁵Peptide 28 was tested.

⁶Peptide 4342 was tested.

⁷Peptide 5 was tested.

⁸Peptide 4337 was tested.

*All peptides were tested individually with each serum specimens. Immunoreactivity of peptides 31–60 aa, 614–638 aa, 403–432 aa and 85–114 aa derived from the HEV ORF2 protein was compared to immunoreactivity of monomer 1; peptides 635–660 aa, 398–427 aa, 95–119 aa derived from the HEV ORF2 protein and 91–123 aa derived from the HEV Mexico strain ORF3 protein to monomer 2; peptides 626-655 aa and 39–64 aa from the HEV ORF2 protein to monomer 3; and peptides 91–123 aa from the HEV Burma strain ORF3 protein and 631–660 aa from the HEV ORF2 protein to monomer 4. Corresponding combination of peptides were compared to dimers and trimer. A full set of peptides was compared to the HEV MA-II.

**The number of serum specimens that are immunoreactive with recombinant protein but not immunoreactive with corresponding synthetic peptides.

***The number of serum specimens out of 73 that are not immunoreactive with individual recombinant proteins but immunoreactive with corresponding synthetic peptides.